Abstract

Flicker sensitivities were measured for more than 100 people age 60 and older with stimulus-conditions originally designed to obtain estimates of preretinal absorption by the lens and macular pigment. Flicker sensitivities were measured on two chromatic backgrounds: a 1000-td, 480-nm background and a 5800-td, Wratten 33 background (approximately metameric with 633 nm). Testing sessions were administered at 18-month intervals across a 3-yr period. No subject tested had a history of glaucoma or ocular hypertension at the time of entry into the study. For ten subjects, however, flicker sensitivity was sometimes reduced by more than 2.0 log units from the mean norm for at least one of the two backgrounds. For most other subjects, flicker sensitivities were within 0.5 log units of the mean norms. On retrospective analysis, the profound reductions of flicker sensitivity (PRFS) were associated significantly with (a) advanced age (perhaps especially when combined with relatively high intraocular pressure), and (b) the use of cardiovascular medications. The PRFS probably were associated with (c) female sex, and (d) large intraocular pressure fluctuations. In addition, the majority of subjects with PRFS were found to have evidence of glaucomatous cupping or field loss. These results suggest that PRFS result from glaucoma or share etiologies with low-tension glaucoma. The use of cardiovascular medications suggested that PRFS could depend on retinal dysfunction rather than on optic nerve compromise alone. Predicted results from two additional subject populations support this possibility. For young healthy subjects, flicker threshold vs illuminance curves attained very steep slopes for sufficiently short wavelength tests on sufficiently extreme long wavelength backgrounds (655 nm, 50,000 td); the steep slopes coincided with the breakdown of effective M-cone isolation. Reductions of flicker sensitivity on the 5800-td Wratten 33 background depended correspondingly on test wavelength for subjects with well-documented low-tension glaucoma.

© 1991 Optical Society of America

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  1. A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
    [PubMed]
  2. A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
    [PubMed]
  3. A. Eisner, S. A. Fleming, J. R. Samples, “Large Selective Losses of Flicker Sensitivity in Older People with Normal IOP and No History of Eye Disease,” Noninvasive Assessment of the Visual System, Technical Digest Series7 (Optical Society of America, Washington, DC, 1989), pp. 28–31.
  4. G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).
  5. Air puff tonometry was used rather than contact tonometry for screening purposes so that the short wavelength stimuli used for psychophysical testing could not cause the cornea to fluoresce.
  6. All but 2 of the 109 subjects have retained 20/30 or better acuity in each eye; one eye of each of two subjects had an acuity loss to 20/40. All but 3 of the 109 subjects had IOP ≤ 22 in each eye at each session. Of the 109 subjects, 30 were male (of whom 18 were age 70 or older) and 79 were female (of whom 44 were age 70 or older). Twenty-six additional subjects who would have been due to return for testing 36 months after study entry were not tested at the time of the third session. These twenty-six subjects included nine who were ill and one who died. Two of these twenty-six subjects had PRFS at the first session. Two additional subjects who had PRFS at the first or second session were tested at the time of the third session, but with a battery of tests not identical to that of the regular third session.
  7. Subjects adapted to the background for a minimum of 2 min prior to flicker threshold measurements. To measure flicker thresholds, a method of limits was used (0.04 log unit steps), in which the illuminance of a flickering test pedestal (100% modulation) was increased until the subject reported seeing flicker. If the examiner judged the flicker thresholds to be systematically decreasing, measurements were taken until the thresholds appeared to stabilize, after which four additional measurements were taken. Flicker sensitivity was computed from the mean of (the last) four flicker threshold settings.
  8. Eyes were dark adapted for at least 7 min between flicker sensitivity and absolute sensitivity measurements. Prior to use of the 480-nm background, S cone sensitivity had been measured on a 1000-td, 580-nm background.
  9. On the Wratten 33 background, a fixation aid (cross hairs with a 4° central gap) was used to facilitate foveal testing. Subjects adapted to the Wratten 33 background for a minimum of 3 min prior to flicker threshold measurements. Flicker sensitivity measurements were preceded by a 25-min period of dark adaptation and subsequent scotopic testing in the parafovea. The dark adaptation period required for scotopic testing itself followed measurement of foveal (photopic) absolute sensitivity.
  10. Corresponding thresholds to 3°, 160-ms flashes were also measured.
  11. Irradiance levels were measured using an EG&G model 550 radiometer with the detector positioned near the exit pupil of the apparatus. These irradiance levels were used to compute photopic illuminances for narrowband stimuli. For broadband stimuli (the Wratten 33 background), photopic illuminance was computed using a two-step procedure. First, to measure the illuminance of the long wavelength light passed by the Wratten 33 filter, a Tektronix model J16 photometer with the J6505 red LED test probe attached was used in combination with a short wavelength blocking filter. Second, to measure the illuminance of the short wavelength component, the difference was computed of two measurements—that of the Wratten 33 background and that of the Wratten 33 background with its short wavelength component blocked—taken with the EG&G model 550 photometer (which does not correctly measure illuminances in the red). In addition, spectroradiometric measurements of broadband stimuli were obtained using an EG&G model 555-61M spectroradiometer. From these spectroradiometric readings, metamerism was computed using the Smith and Pokorny estimates of M and L cone spectral sensitivities. [V. C. Smith, J. Pokorny, “Appendix, Part III (1975),” in R. M. Boynton, Human Color VisionHolt, Rinehart and Winston, New York, p. 404]. Flicker rate was calibrated by feeding the radiometer signal to an oscilloscope. Any intersession variation of flicker rate was appreciably <0.8 Hz, which corresponds to the thickness of the oscilloscope trace at 20 Hz.
  12. For one subject with a PRFS, who was tested only once, the grader was in effect unmasked. That subject was judged to have a glaucotomous optic nerve head.
  13. For nine subjects considered normal, photographs could not be graded for both eyes for every session. One of these nine subjects had a PRFS and was not tested at the third session; for five other subjects, the first or second session photographs could not be graded for each eye, but all the other photographs were graded as normal. For the remaining three of nine subjects, a third session photograph could not be graded. These three subjects were considered normal because none of the twenty-seven subjects assigned a non-normal grade at the third session would have been assigned a normal grade on the basis of the first and second session photographs alone.
  14. All four subjects with PRFS at a regularly scheduled testing session were later retested using the 480-nm background at one or more supplemental testing sessions. Subject D was tested at one supplemental testing session; flicker sensitivity was again normal in each eye. Subject A was tested at three supplemental sessions, with variable results: (i) normal flicker sensitivity in each eye, (ii) normal in one eye, but at the low end of the non-PRFS range in the fellow eye, and (iii) grossly reduced (about 9 standard deviations) in each eye. Subjects B and C were each tested at one supplemental session. Each had a PRFS in one eye, but normal flicker sensitivities in the fellow eye. However, following a change of test wavelength from 660 to 490 nm after ~10 min of testing, the flicker sensitivity of subject B became immeasurably low at all test wavelengths for as long as testing continued. Although flicker sensitivity became profoundly reduced, sensitivity for detection of the test stimuli changed little or not at all.
  15. Of the six subjects with a PRFS (subjects E–J), five were later retested foveally using the Wratten 33 background at supplemental testing sessions. Stimulus history was not standardized at these supplemental sessions. At the supplemental sessions, subjects F and I had PRFS, the flicker sensitivity of subject J was at the low end of the non-PRFS range, and subjects E and G had normal flicker sensitivities. For subjects F and I, however, flicker sensitivities abruptly became normal, several minutes after having apparently stabilized at profoundly reduced levels. For both these subjects, flicker sensitivity became normal immediately following a change of test wavelength from 490 to 570 nm.
  16. Like other subjects tested with the Wratten 33 background at supplemental sessions, the flicker sensitivity of subject A eventually became normal.
  17. When the association of PRFS with age was evaluated separately for two backgrounds, the association with advanced age remained significant (p < 0.01) for the 480-nm background, and became marginally nonsignificant (p = 0.06) for the Wratten 33 background.
  18. For subjects without PRFS, the normal age-related losses on Wratten 33 backgrounds were neither pronounced nor universal and did not become evident until about age 75–80. However, flicker sensitivity at 570 nm on the Wratten 33 background did decrease significantly with age foveally (Spearman r = −0.25, p < 0.01, one-sided test), but not parafoveally (Spearman r = −0.12). The twenty-one non-PRFS subjects for whom flicker sensitivity was greater parafoveally than foveally were significant older (mean age 73.4 yr) than the non-PRFS subjects for whom flicker sensitivity was greater foveally than parafoveally (mean age 70.3 yr) (p = 0.008, two-sided Mann-Whitney U test). This post hoc comparison indicates that the age-related decrease of flicker sensitivity (on the Wratten 33 background) is greater foveally than parafoveally, even though the straightforward comparison of foveal and parafoveal flicker sensitivities was not quite statistically significant (Spearman r of the difference = −0.16). For a 480-nm test on a 480-nm background, flicker sensitivity also decreased significantly with age (Spearman r = −0.31, p < 0.001), as did the difference between 20-Hz sensitivity and sensitivity to 160-ms flashes (Spearman r = −0.19, p < 0.05). However, for backgrounds that are much affected by age-related changes of preretinal absorption, as 480-nm backgrounds are, the difference between sensitivities at two temporal frequencies depends very much on the slopes of the TVI curves.
  19. C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
    [PubMed]
  20. For a 570-nm test on the Wratten 33 background, Spearman r = 0.13. For a 480-nm test on the 480-nm background, Spearman r = 0.02.
  21. Y. Kitazawa, T. Horie, “Diurnal Variation of Intraocular Pressure in Primary Open-Angle Glaucoma,” Am. J. Ophthalmol. 79, 557–566 (1975).
    [PubMed]
  22. For the 480-nm background considered separately, the association of PRFS with the combination of advanced age and relatively high IOP remained significant (p = 0.047). For the Wratten 33 background, the association remained significant (p = 0.037) only if the eye with an IOP equal to the median and with large IOP fluctuations was considered to have a relatively high IOP.
  23. However, since nineteen of twenty-five people were judged to have suspicious or glaucomatous changes in one eye only and since flicker sensitivity was measured on Wratten 33 backgrounds for one eye only, the p-value of 0.087 should be considered to be an upper bound for the true p-value.
  24. J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
    [Crossref] [PubMed]
  25. The visual fields for five subjects were measured using the Humphrey 30-2 program; the visual fields for subjects-A and G were measured using Goldman manual perimetry.
  26. A. Eisner, “Macular Function in Normal Aging: Loss of Flicker Sensitivity in Two Individuals,” Noninvasive Assessment of Visual Function, Technical Digest Series (Optical Society of America, Washington, DC, 1985), pp. TuA51–TuA54.
  27. U. Gerber, G. Niemeyer, “B-Adrenergic Antagonists Modify Retinal Function in the Perfused Cat Eye,” Clin. Vis. Sci. 3, 255–266 (1988).
  28. A history for use of any type of cardiovascular medication (antihypertension or cardiac vasodilator, inclusive) was not quite significantly associated for PRFS on the two backgrounds considered separately (p = 0.076 and p = 0.052 [two-sided tests]) for the 480-nm and Wratten 33 backgrounds, respectively.
  29. All subjects with PRFS who were using cardiac vasodilators were using such medication regularly; two subjects without PRFS were using only nitroglycerine as needed. Of the six subjects with PRFS who were using antihypertension medication, three had used β-blockers. Of the eighteen subjects without PRFS who had used antihypertension medication, six had used β-blockers; two of these six had not used any other antihypertension medication.
  30. M. J. Mayer, C. B. Y. Kim, A. Svingos, A. Glucs, “Foveal Flicker Sensitivity in Healthy Aging Eyes. I. Compensating for Pupil Variation,” J. Opt. Soc. Am. A 5, 2201–2209 (1988).
    [Crossref] [PubMed]
  31. U. Tulunay-Keesey, J. N. Ver Hoeve, C. Terkla-McGrane, “Threshold and Suprathreshold Spatiotemporal Response Throughout Adulthood,” J. Opt. Soc. Am. A 5, 2191–2200 (1988).
    [Crossref] [PubMed]
  32. C. W. Tyler, “Two Processes Control Variations in Flicker Sensitivity over the Life Span,” J. Opt. Soc. Am. A 6, 481–490 (1989).
    [Crossref] [PubMed]
  33. C. E. Wright, N. Drasdo, “The Influence of Age on the Spatial and Temporal Contrast Sensitivity Function,” Doc. Ophthalmol. 59, 385–395 (1985).
    [Crossref] [PubMed]
  34. S. M. Drance, “Some Factors in the Production of Low Tension Glaucoma,” Br. J. Ophthalmol. 56, 229–242 (1972).
    [Crossref] [PubMed]
  35. L. C. Chumbley, R. F. Brubaker, “Low Tension Glaucoma,” Am. J. Ophthalmol. 81, 761–767 (1976).
    [PubMed]
  36. I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
    [Crossref] [PubMed]
  37. R. Z. Levene, “Low Tension Glaucoma: a Critical Review and New Material,” Surv. Ophthalmol. 24, 621–664 (1980).
    [Crossref] [PubMed]
  38. H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
    [PubMed]
  39. H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
    [PubMed]
  40. V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
    [Crossref] [PubMed]
  41. M. Conley, D. Fitzpatrick, “Morphology of retinogeniculate axons in the macaque,” Visual Neuroscience 2, 287–296 (1989).
    [Crossref] [PubMed]
  42. B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
    [PubMed]
  43. B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
    [PubMed]
  44. S. S. Hayreh, “Blood Supply of the Anterior Optic Nerve,” in The Glaucomas, Vol. I, R. Ritch, M. B. Shields, T. Krupin, Eds. (C.V. Mosby, St. Louis MO., 1989), pp. 133–161.
  45. W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
    [PubMed]
  46. J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).
  47. J. B. Jonas, G. O. H. Naumann, “Parapapillary Retinal Vessel Diameter in Normal and Glaucoma Eyes. II. Correlations,” Invest. Ophthalmol. Vis. Sci. 30, 1604–1611 (1989).
    [PubMed]
  48. A. Alm, A. Bill, “Ocular and Optic Nerve Blood Flow at Normal and Increased Intraocular Pressures in Monkeys (Macaca irus): a Study with Radioactively Labelled Microspheres Including Flow Determinations in Brain and Some Other Tissues,” Exp. Eye Res. 15, 15–29 (1973).
    [Crossref] [PubMed]
  49. R. A. Linsenmeier, “Effects of Light and Darkness on Oxygen Distribution and Consumption in the Cat Retina,” J. Gen. Physiol. 88, 521–542 (1986).
    [Crossref] [PubMed]
  50. X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
    [PubMed]
  51. M. K. Ryan, A. E. Hendrikson, “Interplexiform Cells in Macaque Monkey Retina,” Exp. Eye Res. 45, 57–66 (1987).
    [Crossref] [PubMed]
  52. M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
    [Crossref] [PubMed]
  53. H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
    [Crossref] [PubMed]
  54. G. Westheimer, “Spatial Interaction in Human Cone Vision,” J. Physiol. London 190, 139–154 (1967).
    [PubMed]
  55. J. M. Enoch, C. R. Fitzgerald, E. C. Campos, “Retinal Receptive Field-Like Properties in Primary Open-Angle Glaucoma,” in Quantitative Layer-by-Layer Perimetry, (Grune & Stratton, New York, 1981), Chap. 6, pp. 168–194.
  56. M. M. Hayhoe, M. V. Smith, “The Role of Spatial Filtering in Sensitivity Regulation,” Vision Res. 29, 457–469 (1989).
    [Crossref] [PubMed]
  57. T. E. Frumkes, T. Eysteinsson, “Suppressive Rod–Cone Interaction in Distal Vertebrate Retina: Intracellular Records from Xenopus and Necturus,” J. Neurophysiol. 57, 1361–1382 (1987).
    [PubMed]
  58. R. Pflug, R. Nelson, “Background Enhancement of Cone Signals in Cat Horizontal Cells,” Invest. Ophthalmol. Vis. Sci. Suppl. 28, 240–000 (1987).
  59. G. B. Arden, T. E. Frumkes, “Stimulation of Rods can Increase Cone Flicker ERGs in Man,” Vision Res. 26, 711–721 (1986).
    [Crossref] [PubMed]
  60. D. H. Hood, “Suppression of the Frog’s Cone System in the Dark,” Vision Res. 12, 889–908 (1972).
    [Crossref] [PubMed]
  61. K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
    [Crossref] [PubMed]
  62. V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).
  63. A. Eisner, “Losses of Foveal Flicker Sensitivity During Dark Adaptation Following Extended Bleaches,” Vision Res. 29, 1401–1423 (1989).
    [Crossref] [PubMed]
  64. N. J. Coletta, U. Houston, College of Optometry; personal communication.
  65. K. R. Alexander, G. A. Fishman, “Rod–Cone Interaction in Flicker Perimetry,” Br. J. Ophthalmol. 68, 303–309 (1984).
    [Crossref] [PubMed]
  66. N. J. Coletta, A. J. Adams, “Spatial Extent of Rod–Cone and Cone–Cone Interactions for Flicker Detection,” Vision Res. 26, 917–925 (1986).
    [Crossref] [PubMed]
  67. S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
    [Crossref] [PubMed]
  68. A. Eisner, “Flicker Sensitivity Losses in Dark Adaptation: Spatial Factors,” OSA Annual Meeting, 1988 Technical Digest Series, Vol. 13 (Optical Society of America, Washington, DC, 1988), p. 67.
  69. J. E. Dowling, The Retina: an Approachable Part of the Brain (Belknap, Cambridge, MA, 1987).
  70. R. Shapley, C. Enroth-Cugell, “Visual Adaptation and Retinal Gain Controls,” Prog. Retinal Res. 3, 263–346 (1984).
    [Crossref]
  71. A. Eisner, D. I. A. MacLeod, “Flicker Photometric Study of Chromatic Adaption: Selective Suppression of Cone Inputs by Colored Backgrounds,” J. Opt. Soc. Am. 71, 705–718 (1981).
    [Crossref] [PubMed]
  72. R. M. Boynton, Human Color Vision (Holt, Rinehart & Winston, New York, 1979).
  73. At bleaching levels, steady-state cone quantum absorption asymptotes toward a maximum [see E. N. Pugh, J. D. Mollon, “A Theory of the pi-1 and pi-3 Color Mechanisms of Stiles,” Vision Res. 19, 293–312 (1979)], thus causing any intrareceptoral response compression to the test stimulus not alleviated by true adaptation [see M. M. Hayhoe et al., “The Time-Course of Multiplicative and Subtractive Adaptation Process,” Vision Res. 27, 1981–1996 (1987)] to also asymptote to a maximum. Therefore, spectrally opponent lateral antagonism is least adequate for background lights that bleach L cones but not M cones.
    [Crossref] [PubMed]
  74. A. Eisner, Good Samaritan Hospital and Medical Center, Portland, OR; unpublished observations.
  75. J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” Appl. Opt. 26, 1437–1440 (1987).
    [Crossref] [PubMed]
  76. W. S. Geisler, “Evidence for the Equivalent-Background Hypothesis in Cones,” Vision Res. 19, 799–805 (1979).
    [Crossref] [PubMed]
  77. Subjects adapted to the different background light levels for a minimum of 3 min, except for backgrounds that immediately followed another background of similar illuminance (not more than 0.2 log units different), in which case the minimum adaptation time was 2 min. Flicker thresholds were almost always computed from the means of four settings. When threshold vs illuminance (TVI) curves were obtained, background illuminance was always increased, except sometimes when probing the ends of steep sections of TVI curves. When threshold vs wavelength (TVλ) curves were obtained, test wavelengths were presented in ascending order beginning with 540 nm, and then in descending order again beginning with 540 nm, and finally, again at 540 nm.
  78. Weber’s law was found to hold for the one subject (SF) tested using long wavelength (640-nm) tests on 656-nm backgrounds incremented in 0.1 log unit steps of illuminance. For both subjects, Weber’s law was found to hold across a 0.44 log unit interval for long wavelength 20 min of arc diam tests on a long pass background. Thus, it is not the case that a fortuitous combination of steep, shallow, and negative slopes caused Weber’s law to appear to hold at long test wavelengths across a 0.75 log unit interval.
  79. An alternative explanation for the spectrally dependent losses of (M-cone mediated) flicker sensitivity does not require any spectrally opponent effects. That is, the M-cone quantum absorption from flashed short wavelength tests may be large enough relative to the M-cone quantum absorption from long wavelength backgrounds to saturate the response of M cones. However, (a) flicker TVI curves measured with flashed stimuli on long wavelength backgrounds were found to be virtually identical to the corresponding flicker TVI curves measured with continuous stimuli (both subjects), while (b) at illuminances just dimmer than those associated with failures of Weber’s law, the time-averaged M cone quantum catch from a 540-nm test was found to be only ~7% that from a 656-nm background (for SF). At longer test wavelengths, the corresponding percentage is appreciably less. Therefore, the alternative explanation that ascribes the failure of Weber’s law entirely to intrareceptoral effects is unlikely to be correct.
  80. H. DeVries, “The Luminosity Curve of the Eye as Determined by Measurements with the Flickerphotometer,” Physica 14, 319–348 (1948).
    [Crossref]
  81. S. Hecht, C. D. Verrijp, “Intermittent Stimulation by Light III. The Relation Between Intensity and Critical Fusion Frequency for Different Retinal Locations,” J. Gen Physiol. 17, 251–268 (1933).
    [Crossref] [PubMed]
  82. D. H. Kelly, H. R. Wilson, “Human Flicker Sensitivity: Two Stages of Retinal Diffusion,” Science 202, 896–899 (1978).
    [Crossref] [PubMed]
  83. C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
    [Crossref] [PubMed]
  84. A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
    [Crossref] [PubMed]
  85. Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
    [PubMed]
  86. Unreported data from the same subjects imply that PRFS also can depend on test size and on the interaction of test size with test wavelength. On the 480-nm backgrounds subject Z had a PRFS, the flicker sensitivities of subjects W and X were at the low end of the non-PRFS continuum, and the flicker sensitivities of subject Y were normal.
  87. Virtually the same spectrally dependent reductions were found at each of two testing sessions for subject X. However, at the first of these two testing sessions, flicker sensitivity appeared to oscillate by more than a log unit for up to ~30 min before stabilizing, at which time the reported values were measured. At the second testing session, flicker sensitivity appeared to stabilize much sooner after onset of the adapting light.
  88. J. S. Werner, V. G. Steele, “Sensitivity of Human Foveal Color Mechanisms Throughout the Life Span,” J. Opt. Soc. Am. A 5, 2122–2130 (1988).
    [Crossref] [PubMed]
  89. A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).
  90. S. L. Alvarez, K. B. Mills, “Spectral and Flicker Sensitivity in Ocular Hypertension and Glaucoma,” Res. Clin. Forum 7, 83–93 (1985).
  91. P. W. Miles, “Flicker Fusion Fields. III. Findings in Early Glaucoma,” Arch. Ophthalmol. 43, 661–677 (1950).
    [Crossref]
  92. A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
    [PubMed]
  93. C. W. Tyler, “Specific Deficits of Flicker Sensitivity in Glaucoma and Ocular Hypertension,” Invest. Ophthalmol. Vis. Sci. 20, 204–212 (1981).
    [PubMed]
  94. R. L. Stamper, “The Effect of Glaucoma on Central Visual Function,” Trans. Am. Ophthalmol. Soc. 82, 792–826 (1984).
    [PubMed]

1991 (1)

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

1990 (1)

W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
[PubMed]

1989 (8)

J. B. Jonas, G. O. H. Naumann, “Parapapillary Retinal Vessel Diameter in Normal and Glaucoma Eyes. II. Correlations,” Invest. Ophthalmol. Vis. Sci. 30, 1604–1611 (1989).
[PubMed]

M. M. Hayhoe, M. V. Smith, “The Role of Spatial Filtering in Sensitivity Regulation,” Vision Res. 29, 457–469 (1989).
[Crossref] [PubMed]

A. Eisner, “Losses of Foveal Flicker Sensitivity During Dark Adaptation Following Extended Bleaches,” Vision Res. 29, 1401–1423 (1989).
[Crossref] [PubMed]

C. W. Tyler, “Two Processes Control Variations in Flicker Sensitivity over the Life Span,” J. Opt. Soc. Am. A 6, 481–490 (1989).
[Crossref] [PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
[PubMed]

M. Conley, D. Fitzpatrick, “Morphology of retinogeniculate axons in the macaque,” Visual Neuroscience 2, 287–296 (1989).
[Crossref] [PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
[PubMed]

Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
[PubMed]

1988 (9)

J. S. Werner, V. G. Steele, “Sensitivity of Human Foveal Color Mechanisms Throughout the Life Span,” J. Opt. Soc. Am. A 5, 2122–2130 (1988).
[Crossref] [PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
[PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
[PubMed]

U. Gerber, G. Niemeyer, “B-Adrenergic Antagonists Modify Retinal Function in the Perfused Cat Eye,” Clin. Vis. Sci. 3, 255–266 (1988).

M. J. Mayer, C. B. Y. Kim, A. Svingos, A. Glucs, “Foveal Flicker Sensitivity in Healthy Aging Eyes. I. Compensating for Pupil Variation,” J. Opt. Soc. Am. A 5, 2201–2209 (1988).
[Crossref] [PubMed]

U. Tulunay-Keesey, J. N. Ver Hoeve, C. Terkla-McGrane, “Threshold and Suprathreshold Spatiotemporal Response Throughout Adulthood,” J. Opt. Soc. Am. A 5, 2191–2200 (1988).
[Crossref] [PubMed]

K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
[Crossref] [PubMed]

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
[PubMed]

1987 (8)

M. K. Ryan, A. E. Hendrikson, “Interplexiform Cells in Macaque Monkey Retina,” Exp. Eye Res. 45, 57–66 (1987).
[Crossref] [PubMed]

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

T. E. Frumkes, T. Eysteinsson, “Suppressive Rod–Cone Interaction in Distal Vertebrate Retina: Intracellular Records from Xenopus and Necturus,” J. Neurophysiol. 57, 1361–1382 (1987).
[PubMed]

R. Pflug, R. Nelson, “Background Enhancement of Cone Signals in Cat Horizontal Cells,” Invest. Ophthalmol. Vis. Sci. Suppl. 28, 240–000 (1987).

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
[Crossref] [PubMed]

A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
[Crossref] [PubMed]

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” Appl. Opt. 26, 1437–1440 (1987).
[Crossref] [PubMed]

1986 (3)

N. J. Coletta, A. J. Adams, “Spatial Extent of Rod–Cone and Cone–Cone Interactions for Flicker Detection,” Vision Res. 26, 917–925 (1986).
[Crossref] [PubMed]

R. A. Linsenmeier, “Effects of Light and Darkness on Oxygen Distribution and Consumption in the Cat Retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

G. B. Arden, T. E. Frumkes, “Stimulation of Rods can Increase Cone Flicker ERGs in Man,” Vision Res. 26, 711–721 (1986).
[Crossref] [PubMed]

1985 (4)

H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
[Crossref] [PubMed]

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

C. E. Wright, N. Drasdo, “The Influence of Age on the Spatial and Temporal Contrast Sensitivity Function,” Doc. Ophthalmol. 59, 385–395 (1985).
[Crossref] [PubMed]

S. L. Alvarez, K. B. Mills, “Spectral and Flicker Sensitivity in Ocular Hypertension and Glaucoma,” Res. Clin. Forum 7, 83–93 (1985).

1984 (6)

R. Shapley, C. Enroth-Cugell, “Visual Adaptation and Retinal Gain Controls,” Prog. Retinal Res. 3, 263–346 (1984).
[Crossref]

R. L. Stamper, “The Effect of Glaucoma on Central Visual Function,” Trans. Am. Ophthalmol. Soc. 82, 792–826 (1984).
[PubMed]

C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
[PubMed]

V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
[Crossref] [PubMed]

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

K. R. Alexander, G. A. Fishman, “Rod–Cone Interaction in Flicker Perimetry,” Br. J. Ophthalmol. 68, 303–309 (1984).
[Crossref] [PubMed]

1983 (1)

S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
[Crossref] [PubMed]

1982 (1)

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

1981 (3)

A. Eisner, D. I. A. MacLeod, “Flicker Photometric Study of Chromatic Adaption: Selective Suppression of Cone Inputs by Colored Backgrounds,” J. Opt. Soc. Am. 71, 705–718 (1981).
[Crossref] [PubMed]

C. W. Tyler, “Specific Deficits of Flicker Sensitivity in Glaucoma and Ocular Hypertension,” Invest. Ophthalmol. Vis. Sci. 20, 204–212 (1981).
[PubMed]

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

1980 (1)

R. Z. Levene, “Low Tension Glaucoma: a Critical Review and New Material,” Surv. Ophthalmol. 24, 621–664 (1980).
[Crossref] [PubMed]

1979 (3)

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

At bleaching levels, steady-state cone quantum absorption asymptotes toward a maximum [see E. N. Pugh, J. D. Mollon, “A Theory of the pi-1 and pi-3 Color Mechanisms of Stiles,” Vision Res. 19, 293–312 (1979)], thus causing any intrareceptoral response compression to the test stimulus not alleviated by true adaptation [see M. M. Hayhoe et al., “The Time-Course of Multiplicative and Subtractive Adaptation Process,” Vision Res. 27, 1981–1996 (1987)] to also asymptote to a maximum. Therefore, spectrally opponent lateral antagonism is least adequate for background lights that bleach L cones but not M cones.
[Crossref] [PubMed]

W. S. Geisler, “Evidence for the Equivalent-Background Hypothesis in Cones,” Vision Res. 19, 799–805 (1979).
[Crossref] [PubMed]

1978 (1)

D. H. Kelly, H. R. Wilson, “Human Flicker Sensitivity: Two Stages of Retinal Diffusion,” Science 202, 896–899 (1978).
[Crossref] [PubMed]

1976 (1)

L. C. Chumbley, R. F. Brubaker, “Low Tension Glaucoma,” Am. J. Ophthalmol. 81, 761–767 (1976).
[PubMed]

1975 (1)

Y. Kitazawa, T. Horie, “Diurnal Variation of Intraocular Pressure in Primary Open-Angle Glaucoma,” Am. J. Ophthalmol. 79, 557–566 (1975).
[PubMed]

1973 (1)

A. Alm, A. Bill, “Ocular and Optic Nerve Blood Flow at Normal and Increased Intraocular Pressures in Monkeys (Macaca irus): a Study with Radioactively Labelled Microspheres Including Flow Determinations in Brain and Some Other Tissues,” Exp. Eye Res. 15, 15–29 (1973).
[Crossref] [PubMed]

1972 (2)

D. H. Hood, “Suppression of the Frog’s Cone System in the Dark,” Vision Res. 12, 889–908 (1972).
[Crossref] [PubMed]

S. M. Drance, “Some Factors in the Production of Low Tension Glaucoma,” Br. J. Ophthalmol. 56, 229–242 (1972).
[Crossref] [PubMed]

1967 (1)

G. Westheimer, “Spatial Interaction in Human Cone Vision,” J. Physiol. London 190, 139–154 (1967).
[PubMed]

1950 (1)

P. W. Miles, “Flicker Fusion Fields. III. Findings in Early Glaucoma,” Arch. Ophthalmol. 43, 661–677 (1950).
[Crossref]

1948 (1)

H. DeVries, “The Luminosity Curve of the Eye as Determined by Measurements with the Flickerphotometer,” Physica 14, 319–348 (1948).
[Crossref]

1933 (1)

S. Hecht, C. D. Verrijp, “Intermittent Stimulation by Light III. The Relation Between Intensity and Critical Fusion Frequency for Different Retinal Locations,” J. Gen Physiol. 17, 251–268 (1933).
[Crossref] [PubMed]

Adams, A.

A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
[Crossref] [PubMed]

Adams, A. J.

N. J. Coletta, A. J. Adams, “Spatial Extent of Rod–Cone and Cone–Cone Interactions for Flicker Detection,” Vision Res. 26, 917–925 (1986).
[Crossref] [PubMed]

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).

Alexander, K. R.

K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
[Crossref] [PubMed]

K. R. Alexander, G. A. Fishman, “Rod–Cone Interaction in Flicker Perimetry,” Br. J. Ophthalmol. 68, 303–309 (1984).
[Crossref] [PubMed]

Alm, A.

A. Alm, A. Bill, “Ocular and Optic Nerve Blood Flow at Normal and Increased Intraocular Pressures in Monkeys (Macaca irus): a Study with Radioactively Labelled Microspheres Including Flow Determinations in Brain and Some Other Tissues,” Exp. Eye Res. 15, 15–29 (1973).
[Crossref] [PubMed]

Alvarez, S. L.

S. L. Alvarez, K. B. Mills, “Spectral and Flicker Sensitivity in Ocular Hypertension and Glaucoma,” Res. Clin. Forum 7, 83–93 (1985).

Arden, G. B.

G. B. Arden, T. E. Frumkes, “Stimulation of Rods can Increase Cone Flicker ERGs in Man,” Vision Res. 26, 711–721 (1986).
[Crossref] [PubMed]

Atkin, A.

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Becker, B.

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

Bielik, M.

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

Bill, A.

A. Alm, A. Bill, “Ocular and Optic Nerve Blood Flow at Normal and Increased Intraocular Pressures in Monkeys (Macaca irus): a Study with Radioactively Labelled Microspheres Including Flow Determinations in Brain and Some Other Tissues,” Exp. Eye Res. 15, 15–29 (1973).
[Crossref] [PubMed]

Bodis-Wollner, I.

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Boynton, R. M.

R. M. Boynton, Human Color Vision (Holt, Rinehart & Winston, New York, 1979).

Brown, B.

G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).

Brubaker, R. F.

L. C. Chumbley, R. F. Brubaker, “Low Tension Glaucoma,” Am. J. Ophthalmol. 81, 761–767 (1976).
[PubMed]

Campos, E. C.

J. M. Enoch, C. R. Fitzgerald, E. C. Campos, “Retinal Receptive Field-Like Properties in Primary Open-Angle Glaucoma,” in Quantitative Layer-by-Layer Perimetry, (Grune & Stratton, New York, 1981), Chap. 6, pp. 168–194.

Carr, R. E.

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

Chumbley, L. C.

L. C. Chumbley, R. F. Brubaker, “Low Tension Glaucoma,” Am. J. Ophthalmol. 81, 761–767 (1976).
[PubMed]

Cole, G. R.

C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
[Crossref] [PubMed]

Coletta, N. J.

N. J. Coletta, A. J. Adams, “Spatial Extent of Rod–Cone and Cone–Cone Interactions for Flicker Detection,” Vision Res. 26, 917–925 (1986).
[Crossref] [PubMed]

N. J. Coletta, U. Houston, College of Optometry; personal communication.

Conley, M.

M. Conley, D. Fitzpatrick, “Morphology of retinogeniculate axons in the macaque,” Visual Neuroscience 2, 287–296 (1989).
[Crossref] [PubMed]

Cowey, A.

V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
[Crossref] [PubMed]

DePaul, K. L.

W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
[PubMed]

Derlacki, D. J.

K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
[Crossref] [PubMed]

DeVries, H.

H. DeVries, “The Luminosity Curve of the Eye as Determined by Measurements with the Flickerphotometer,” Physica 14, 319–348 (1948).
[Crossref]

Dowling, J. E.

X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
[PubMed]

J. E. Dowling, The Retina: an Approachable Part of the Brain (Belknap, Cambridge, MA, 1987).

Drance, S. M.

Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
[PubMed]

S. M. Drance, “Some Factors in the Production of Low Tension Glaucoma,” Br. J. Ophthalmol. 56, 229–242 (1972).
[Crossref] [PubMed]

Drasdo, N.

C. E. Wright, N. Drasdo, “The Influence of Age on the Spatial and Temporal Contrast Sensitivity Function,” Doc. Ophthalmol. 59, 385–395 (1985).
[Crossref] [PubMed]

Dunkelberger, G. R.

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
[PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
[PubMed]

Eisner, A.

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

A. Eisner, “Losses of Foveal Flicker Sensitivity During Dark Adaptation Following Extended Bleaches,” Vision Res. 29, 1401–1423 (1989).
[Crossref] [PubMed]

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

A. Eisner, D. I. A. MacLeod, “Flicker Photometric Study of Chromatic Adaption: Selective Suppression of Cone Inputs by Colored Backgrounds,” J. Opt. Soc. Am. 71, 705–718 (1981).
[Crossref] [PubMed]

A. Eisner, “Flicker Sensitivity Losses in Dark Adaptation: Spatial Factors,” OSA Annual Meeting, 1988 Technical Digest Series, Vol. 13 (Optical Society of America, Washington, DC, 1988), p. 67.

A. Eisner, Good Samaritan Hospital and Medical Center, Portland, OR; unpublished observations.

A. Eisner, S. A. Fleming, J. R. Samples, “Large Selective Losses of Flicker Sensitivity in Older People with Normal IOP and No History of Eye Disease,” Noninvasive Assessment of the Visual System, Technical Digest Series7 (Optical Society of America, Washington, DC, 1989), pp. 28–31.

A. Eisner, “Macular Function in Normal Aging: Loss of Flicker Sensitivity in Two Individuals,” Noninvasive Assessment of Visual Function, Technical Digest Series (Optical Society of America, Washington, DC, 1985), pp. TuA51–TuA54.

Enoch, J. M.

J. M. Enoch, C. R. Fitzgerald, E. C. Campos, “Retinal Receptive Field-Like Properties in Primary Open-Angle Glaucoma,” in Quantitative Layer-by-Layer Perimetry, (Grune & Stratton, New York, 1981), Chap. 6, pp. 168–194.

Enroth-Cugell, C.

R. Shapley, C. Enroth-Cugell, “Visual Adaptation and Retinal Gain Controls,” Prog. Retinal Res. 3, 263–346 (1984).
[Crossref]

Eysteinsson, T.

T. E. Frumkes, T. Eysteinsson, “Suppressive Rod–Cone Interaction in Distal Vertebrate Retina: Intracellular Records from Xenopus and Necturus,” J. Neurophysiol. 57, 1361–1382 (1987).
[PubMed]

Fishman, G. A.

K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
[Crossref] [PubMed]

K. R. Alexander, G. A. Fishman, “Rod–Cone Interaction in Flicker Perimetry,” Br. J. Ophthalmol. 68, 303–309 (1984).
[Crossref] [PubMed]

Fitzgerald, C. R.

J. M. Enoch, C. R. Fitzgerald, E. C. Campos, “Retinal Receptive Field-Like Properties in Primary Open-Angle Glaucoma,” in Quantitative Layer-by-Layer Perimetry, (Grune & Stratton, New York, 1981), Chap. 6, pp. 168–194.

Fitzpatrick, D.

M. Conley, D. Fitzpatrick, “Morphology of retinogeniculate axons in the macaque,” Visual Neuroscience 2, 287–296 (1989).
[Crossref] [PubMed]

Fleming, S. A.

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

A. Eisner, S. A. Fleming, J. R. Samples, “Large Selective Losses of Flicker Sensitivity in Older People with Normal IOP and No History of Eye Disease,” Noninvasive Assessment of the Visual System, Technical Digest Series7 (Optical Society of America, Washington, DC, 1989), pp. 28–31.

Frumkes, T. E.

T. E. Frumkes, T. Eysteinsson, “Suppressive Rod–Cone Interaction in Distal Vertebrate Retina: Intracellular Records from Xenopus and Necturus,” J. Neurophysiol. 57, 1361–1382 (1987).
[PubMed]

G. B. Arden, T. E. Frumkes, “Stimulation of Rods can Increase Cone Flicker ERGs in Man,” Vision Res. 26, 711–721 (1986).
[Crossref] [PubMed]

S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
[Crossref] [PubMed]

Geisler, W. S.

W. S. Geisler, “Evidence for the Equivalent-Background Hypothesis in Cones,” Vision Res. 19, 799–805 (1979).
[Crossref] [PubMed]

Gerber, U.

U. Gerber, G. Niemeyer, “B-Adrenergic Antagonists Modify Retinal Function in the Perfused Cat Eye,” Clin. Vis. Sci. 3, 255–266 (1988).

Glucs, A.

Goldberg, I.

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

Goldberg, S. H.

S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
[Crossref] [PubMed]

Green, W. R.

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
[PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
[PubMed]

Greenstein, V. C.

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

Grunwold, J. E.

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

Gur, M.

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

Haegerstrom-Portnoy, G.

G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).

Hayhoe, M. M.

M. M. Hayhoe, M. V. Smith, “The Role of Spatial Filtering in Sensitivity Regulation,” Vision Res. 29, 457–469 (1989).
[Crossref] [PubMed]

Hayreh, S. S.

S. S. Hayreh, “Blood Supply of the Anterior Optic Nerve,” in The Glaucomas, Vol. I, R. Ritch, M. B. Shields, T. Krupin, Eds. (C.V. Mosby, St. Louis MO., 1989), pp. 133–161.

Hecht, S.

S. Hecht, C. D. Verrijp, “Intermittent Stimulation by Light III. The Relation Between Intensity and Critical Fusion Frequency for Different Retinal Locations,” J. Gen Physiol. 17, 251–268 (1933).
[Crossref] [PubMed]

Hendrikson, A. E.

M. K. Ryan, A. E. Hendrikson, “Interplexiform Cells in Macaque Monkey Retina,” Exp. Eye Res. 45, 57–66 (1987).
[Crossref] [PubMed]

Heron, G.

A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
[Crossref] [PubMed]

Heynen, H.

H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
[Crossref] [PubMed]

Hollows, F. C.

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

Hood, D. C.

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

Hood, D. H.

D. H. Hood, “Suppression of the Frog’s Cone System in the Dark,” Vision Res. 12, 889–908 (1972).
[Crossref] [PubMed]

Horie, T.

Y. Kitazawa, T. Horie, “Diurnal Variation of Intraocular Pressure in Primary Open-Angle Glaucoma,” Am. J. Ophthalmol. 79, 557–566 (1975).
[PubMed]

Houston, U.

N. J. Coletta, U. Houston, College of Optometry; personal communication.

Husted, R.

A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
[Crossref] [PubMed]

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

Jampolsky, A.

G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).

Jonas, J. B.

J. B. Jonas, G. O. H. Naumann, “Parapapillary Retinal Vessel Diameter in Normal and Glaucoma Eyes. II. Correlations,” Invest. Ophthalmol. Vis. Sci. 30, 1604–1611 (1989).
[PubMed]

Kass, M. A.

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

Kaufman, P. L.

W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
[PubMed]

Keates, E. U.

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

Kelly, D. H.

D. H. Kelly, H. R. Wilson, “Human Flicker Sensitivity: Two Stages of Retinal Diffusion,” Science 202, 896–899 (1978).
[Crossref] [PubMed]

Kim, C. B. Y.

Kitazawa, Y.

Y. Kitazawa, T. Horie, “Diurnal Variation of Intraocular Pressure in Primary Open-Angle Glaucoma,” Am. J. Ophthalmol. 79, 557–566 (1975).
[PubMed]

Klein, M. L.

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

Kronauer, R. E.

C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
[Crossref] [PubMed]

Lakowski, R.

Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
[PubMed]

Lee, B. B.

B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
[PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
[PubMed]

Levene, R. Z.

R. Z. Levene, “Low Tension Glaucoma: a Critical Review and New Material,” Surv. Ophthalmol. 24, 621–664 (1980).
[Crossref] [PubMed]

Linsenmeier, R. A.

R. A. Linsenmeier, “Effects of Light and Darkness on Oxygen Distribution and Consumption in the Cat Retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

Lutze, M.

MacLeod, D. I. A.

Martin, P. R.

B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
[PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
[PubMed]

Mauldin, W. M.

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

Mayer, M. J.

Miles, P. W.

P. W. Miles, “Flicker Fusion Fields. III. Findings in Early Glaucoma,” Arch. Ophthalmol. 43, 661–677 (1950).
[Crossref]

Mills, K. B.

S. L. Alvarez, K. B. Mills, “Spectral and Flicker Sensitivity in Ocular Hypertension and Glaucoma,” Res. Clin. Forum 7, 83–93 (1985).

Mollon, J. D.

At bleaching levels, steady-state cone quantum absorption asymptotes toward a maximum [see E. N. Pugh, J. D. Mollon, “A Theory of the pi-1 and pi-3 Color Mechanisms of Stiles,” Vision Res. 19, 293–312 (1979)], thus causing any intrareceptoral response compression to the test stimulus not alleviated by true adaptation [see M. M. Hayhoe et al., “The Time-Course of Multiplicative and Subtractive Adaptation Process,” Vision Res. 27, 1981–1996 (1987)] to also asymptote to a maximum. Therefore, spectrally opponent lateral antagonism is least adequate for background lights that bleach L cones but not M cones.
[Crossref] [PubMed]

Moss, A.

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Naumann, G. O. H.

J. B. Jonas, G. O. H. Naumann, “Parapapillary Retinal Vessel Diameter in Normal and Glaucoma Eyes. II. Correlations,” Invest. Ophthalmol. Vis. Sci. 30, 1604–1611 (1989).
[PubMed]

Nelson, R.

R. Pflug, R. Nelson, “Background Enhancement of Cone Signals in Cat Horizontal Cells,” Invest. Ophthalmol. Vis. Sci. Suppl. 28, 240–000 (1987).

Neumann, E.

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

Niemeyer, G.

U. Gerber, G. Niemeyer, “B-Adrenergic Antagonists Modify Retinal Function in the Perfused Cat Eye,” Clin. Vis. Sci. 3, 255–266 (1988).

Nygaard, R. W.

S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
[Crossref] [PubMed]

Oehler, R.

V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
[Crossref] [PubMed]

Perry, V. H.

V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
[Crossref] [PubMed]

Petrig, B. L.

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

Pflug, R.

R. Pflug, R. Nelson, “Background Enhancement of Cone Signals in Cat Horizontal Cells,” Invest. Ophthalmol. Vis. Sci. Suppl. 28, 240–000 (1987).

Podos, S. M.

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Pokorny, J.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” Appl. Opt. 26, 1437–1440 (1987).
[Crossref] [PubMed]

Irradiance levels were measured using an EG&G model 550 radiometer with the detector positioned near the exit pupil of the apparatus. These irradiance levels were used to compute photopic illuminances for narrowband stimuli. For broadband stimuli (the Wratten 33 background), photopic illuminance was computed using a two-step procedure. First, to measure the illuminance of the long wavelength light passed by the Wratten 33 filter, a Tektronix model J16 photometer with the J6505 red LED test probe attached was used in combination with a short wavelength blocking filter. Second, to measure the illuminance of the short wavelength component, the difference was computed of two measurements—that of the Wratten 33 background and that of the Wratten 33 background with its short wavelength component blocked—taken with the EG&G model 550 photometer (which does not correctly measure illuminances in the red). In addition, spectroradiometric measurements of broadband stimuli were obtained using an EG&G model 555-61M spectroradiometer. From these spectroradiometric readings, metamerism was computed using the Smith and Pokorny estimates of M and L cone spectral sensitivities. [V. C. Smith, J. Pokorny, “Appendix, Part III (1975),” in R. M. Boynton, Human Color VisionHolt, Rinehart and Winston, New York, p. 404]. Flicker rate was calibrated by feeding the radiometer signal to an oscilloscope. Any intersession variation of flicker rate was appreciably <0.8 Hz, which corresponds to the thickness of the oscilloscope trace at 20 Hz.

Pugh, E. N.

At bleaching levels, steady-state cone quantum absorption asymptotes toward a maximum [see E. N. Pugh, J. D. Mollon, “A Theory of the pi-1 and pi-3 Color Mechanisms of Stiles,” Vision Res. 19, 293–312 (1979)], thus causing any intrareceptoral response compression to the test stimulus not alleviated by true adaptation [see M. M. Hayhoe et al., “The Time-Course of Multiplicative and Subtractive Adaptation Process,” Vision Res. 27, 1981–1996 (1987)] to also asymptote to a maximum. Therefore, spectrally opponent lateral antagonism is least adequate for background lights that bleach L cones but not M cones.
[Crossref] [PubMed]

Quigley, H. A.

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
[PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
[PubMed]

Riva, C. E.

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

Rodic, R.

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

Ryan, M. K.

M. K. Ryan, A. E. Hendrikson, “Interplexiform Cells in Macaque Monkey Retina,” Exp. Eye Res. 45, 57–66 (1987).
[Crossref] [PubMed]

Ryu, S.

C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
[PubMed]

Samples, J. R.

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

A. Eisner, S. A. Fleming, J. R. Samples, “Large Selective Losses of Flicker Sensitivity in Older People with Normal IOP and No History of Eye Disease,” Noninvasive Assessment of the Visual System, Technical Digest Series7 (Optical Society of America, Washington, DC, 1989), pp. 28–31.

Shapley, R.

R. Shapley, C. Enroth-Cugell, “Visual Adaptation and Retinal Gain Controls,” Prog. Retinal Res. 3, 263–346 (1984).
[Crossref]

Shults, W. T.

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

Siegel, I. M.

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

Smith, M. V.

M. M. Hayhoe, M. V. Smith, “The Role of Spatial Filtering in Sensitivity Regulation,” Vision Res. 29, 457–469 (1989).
[Crossref] [PubMed]

Smith, V. C.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” Appl. Opt. 26, 1437–1440 (1987).
[Crossref] [PubMed]

Irradiance levels were measured using an EG&G model 550 radiometer with the detector positioned near the exit pupil of the apparatus. These irradiance levels were used to compute photopic illuminances for narrowband stimuli. For broadband stimuli (the Wratten 33 background), photopic illuminance was computed using a two-step procedure. First, to measure the illuminance of the long wavelength light passed by the Wratten 33 filter, a Tektronix model J16 photometer with the J6505 red LED test probe attached was used in combination with a short wavelength blocking filter. Second, to measure the illuminance of the short wavelength component, the difference was computed of two measurements—that of the Wratten 33 background and that of the Wratten 33 background with its short wavelength component blocked—taken with the EG&G model 550 photometer (which does not correctly measure illuminances in the red). In addition, spectroradiometric measurements of broadband stimuli were obtained using an EG&G model 555-61M spectroradiometer. From these spectroradiometric readings, metamerism was computed using the Smith and Pokorny estimates of M and L cone spectral sensitivities. [V. C. Smith, J. Pokorny, “Appendix, Part III (1975),” in R. M. Boynton, Human Color VisionHolt, Rinehart and Winston, New York, p. 404]. Flicker rate was calibrated by feeding the radiometer signal to an oscilloscope. Any intersession variation of flicker rate was appreciably <0.8 Hz, which corresponds to the thickness of the oscilloscope trace at 20 Hz.

Sponsel, W. E.

W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
[PubMed]

Stamper, R.

C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
[PubMed]

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

Stamper, R. L.

R. L. Stamper, “The Effect of Glaucoma on Central Visual Function,” Trans. Am. Ophthalmol. Soc. 82, 792–826 (1984).
[PubMed]

Steele, V. G.

Stone, R. A.

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

Stoumbos, V. D.

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

Stromeyer, C. F.

C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
[Crossref] [PubMed]

Svingos, A.

Terkla-McGrane, C.

Tornqvist, K.

X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
[PubMed]

Tulunay-Keesey, U.

Tyler, C. W.

C. W. Tyler, “Two Processes Control Variations in Flicker Sensitivity over the Life Span,” J. Opt. Soc. Am. A 6, 481–490 (1989).
[Crossref] [PubMed]

C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
[PubMed]

C. W. Tyler, “Specific Deficits of Flicker Sensitivity in Glaucoma and Ocular Hypertension,” Invest. Ophthalmol. Vis. Sci. 20, 204–212 (1981).
[PubMed]

Valberg, A.

B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
[PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
[PubMed]

Van Buskirk, E. M.

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

Van Dyk, H. J. L.

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

van Norren, D.

H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
[Crossref] [PubMed]

Ver Hoeve, J. N.

Verrijp, C. D.

S. Hecht, C. D. Verrijp, “Intermittent Stimulation by Light III. The Relation Between Intensity and Critical Fusion Frequency for Different Retinal Locations,” J. Gen Physiol. 17, 251–268 (1933).
[Crossref] [PubMed]

Wachtmeister, L.

H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
[Crossref] [PubMed]

Werner, J. S.

Westheimer, G.

G. Westheimer, “Spatial Interaction in Human Cone Vision,” J. Physiol. London 190, 139–154 (1967).
[PubMed]

Wilson, H. R.

D. H. Kelly, H. R. Wilson, “Human Flicker Sensitivity: Two Stages of Retinal Diffusion,” Science 202, 896–899 (1978).
[Crossref] [PubMed]

Wolkstein, M.

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Wright, C. E.

C. E. Wright, N. Drasdo, “The Influence of Age on the Spatial and Temporal Contrast Sensitivity Function,” Doc. Ophthalmol. 59, 385–395 (1985).
[Crossref] [PubMed]

Yamazaki, Y.

Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
[PubMed]

Yang, X. L.

X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
[PubMed]

Zeevi, Y. Y.

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

Am. J. Ophthalmol. (5)

Y. Kitazawa, T. Horie, “Diurnal Variation of Intraocular Pressure in Primary Open-Angle Glaucoma,” Am. J. Ophthalmol. 79, 557–566 (1975).
[PubMed]

L. C. Chumbley, R. F. Brubaker, “Low Tension Glaucoma,” Am. J. Ophthalmol. 81, 761–767 (1976).
[PubMed]

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Retinal Ganglion Cell Atrophy Correlated with Automated Perimetry in Human Eyes with Glaucoma,” Am. J. Ophthalmol. 107, 453–464 (1989).
[PubMed]

W. E. Sponsel, K. L. DePaul, P. L. Kaufman, “Correlation of Visual Function and Retinal Leukocyte Velocity in Glaucoma,” Am. J. Ophthalmol. 109, 49–54 (1990).
[PubMed]

A. Atkin, I. Bodis-Wollner, M. Wolkstein, A. Moss, S. M. Podos, “Abnormalities of Central Contrast Sensitivity in Glaucoma,” Am. J. Ophthalmol. 88, 205–211 (1979).
[PubMed]

Appl. Opt. (1)

Arch. Ophthalmol. (3)

J. R. Samples, E. M. Van Buskirk, W. T. Shults, H. J. L. Van Dyk, “Optic Nerve Head Drusen and Glaucoma,” Arch. Ophthalmol. 103, 1678–1680 (1985).
[Crossref] [PubMed]

P. W. Miles, “Flicker Fusion Fields. III. Findings in Early Glaucoma,” Arch. Ophthalmol. 43, 661–677 (1950).
[Crossref]

A. Adams, G. Heron, R. Husted, “Clinical Measures of Central Vision Function in Glaucoma and Ocular Hypertension,” Arch. Ophthalmol. 105, 782–787 (1987).
[Crossref] [PubMed]

Br. J. Ophthalmol. (3)

I. Goldberg, F. C. Hollows, M. A. Kass, B. Becker, “Systemic Factors in Patients with Low-Tension Glaucoma,” Br. J. Ophthalmol. 65, 56–62 (1981).
[Crossref] [PubMed]

S. M. Drance, “Some Factors in the Production of Low Tension Glaucoma,” Br. J. Ophthalmol. 56, 229–242 (1972).
[Crossref] [PubMed]

K. R. Alexander, G. A. Fishman, “Rod–Cone Interaction in Flicker Perimetry,” Br. J. Ophthalmol. 68, 303–309 (1984).
[Crossref] [PubMed]

Clin. Vis. Sci. (2)

V. C. Greenstein, D. C. Hood, I. M. Siegel, R. E. Carr, “A Possible Use of Rod–Cone Interaction in Congenital Stationary Nightblindness,” Clin. Vis. Sci. 3, 69–74 (1988).

U. Gerber, G. Niemeyer, “B-Adrenergic Antagonists Modify Retinal Function in the Perfused Cat Eye,” Clin. Vis. Sci. 3, 255–266 (1988).

Curr. Eye Res. (1)

M. Gur, Y. Y. Zeevi, M. Bielik, E. Neumann, “Changes in the Oscillatory Potentials of the Electroretinogram in Glaucoma,” Curr. Eye Res. 6, 457–466 (1987).
[Crossref] [PubMed]

Doc. Ophthalmol. (1)

C. E. Wright, N. Drasdo, “The Influence of Age on the Spatial and Temporal Contrast Sensitivity Function,” Doc. Ophthalmol. 59, 385–395 (1985).
[Crossref] [PubMed]

Exp. Eye Res. (2)

A. Alm, A. Bill, “Ocular and Optic Nerve Blood Flow at Normal and Increased Intraocular Pressures in Monkeys (Macaca irus): a Study with Radioactively Labelled Microspheres Including Flow Determinations in Brain and Some Other Tissues,” Exp. Eye Res. 15, 15–29 (1973).
[Crossref] [PubMed]

M. K. Ryan, A. E. Hendrikson, “Interplexiform Cells in Macaque Monkey Retina,” Exp. Eye Res. 45, 57–66 (1987).
[Crossref] [PubMed]

Invest. Ophthalmol. (1)

A. J. Adams, R. Rodic, R. Husted, R. Stamper, “Spectral Sensitivity and Color Discrimination Changes in Glaucoma and Glaucoma-Suspect Patients,” Invest. Ophthalmol. 23, 516–524 (1982).

Invest. Ophthalmol. Vis. Sci. (5)

C. W. Tyler, “Specific Deficits of Flicker Sensitivity in Glaucoma and Ocular Hypertension,” Invest. Ophthalmol. Vis. Sci. 20, 204–212 (1981).
[PubMed]

J. B. Jonas, G. O. H. Naumann, “Parapapillary Retinal Vessel Diameter in Normal and Glaucoma Eyes. II. Correlations,” Invest. Ophthalmol. Vis. Sci. 30, 1604–1611 (1989).
[PubMed]

C. W. Tyler, S. Ryu, R. Stamper, “The Relation Between Visual Sensitivity and Intraocular Pressure in Normal Eyes,” Invest. Ophthalmol. Vis. Sci. 25, 103–105 (1984).
[PubMed]

A. Eisner, S. A. Fleming, M. L. Klein, W. M. Mauldin, “Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms,” Invest. Ophthalmol. Vis. Sci. 28, 1824–1831 (1987).
[PubMed]

A. Eisner, V. D. Stoumbos, M. L. Klein, S. A. Fleming, “Relations between Fundus Appearance and Function: Eyes Whose Fellow Eye has Exudative Age-Related Macular Degeneration,” Invest. Ophthalmol. Vis. Sci. 32, 8–20, (1991).
[PubMed]

Invest. Ophthalmol. Vis. Sci. Suppl. (1)

R. Pflug, R. Nelson, “Background Enhancement of Cone Signals in Cat Horizontal Cells,” Invest. Ophthalmol. Vis. Sci. Suppl. 28, 240–000 (1987).

J. Gen Physiol. (1)

S. Hecht, C. D. Verrijp, “Intermittent Stimulation by Light III. The Relation Between Intensity and Critical Fusion Frequency for Different Retinal Locations,” J. Gen Physiol. 17, 251–268 (1933).
[Crossref] [PubMed]

J. Gen. Physiol. (1)

R. A. Linsenmeier, “Effects of Light and Darkness on Oxygen Distribution and Consumption in the Cat Retina,” J. Gen. Physiol. 88, 521–542 (1986).
[Crossref] [PubMed]

J. Neurophysiol. (1)

T. E. Frumkes, T. Eysteinsson, “Suppressive Rod–Cone Interaction in Distal Vertebrate Retina: Intracellular Records from Xenopus and Necturus,” J. Neurophysiol. 57, 1361–1382 (1987).
[PubMed]

J. Neurosci. (1)

X. L. Yang, K. Tornqvist, J. E. Dowling, “Modulation of Cone Horizontal Cell Activity in the Teleost Fish Retina. II. Role of Interplexiform Cells and Dopamine in Regulating Light Responsiveness,” J. Neurosci. 8, 2269–2278 (1988).
[PubMed]

J. Opt. Soc. Am. (1)

J. Opt. Soc. Am. A (4)

J. Physiol. London (3)

B. B. Lee, P. R. Martin, A. Valberg, “Sensitivity of Macaque Retinal Ganglion Cells to Chromatic and Luminance Flicker,” J. Physiol. London 414, 223–243 (1989).
[PubMed]

B. B. Lee, P. R. Martin, A. Valberg, “The Physiological Basis of Heterochromatic Flicker Photometry Demonstrated in the Ganglion Cells of the Macaque Retina,” J. Physiol. London 404, 323–347 (1988).
[PubMed]

G. Westheimer, “Spatial Interaction in Human Cone Vision,” J. Physiol. London 190, 139–154 (1967).
[PubMed]

Neuroscience (1)

V. H. Perry, R. Oehler, A. Cowey, “Retinal Ganglion Cells that Project to the Dorsal Lateral Geniculate Nucleus in the Macaque Monkey,” Neuroscience 12, 1101–1123 (1984).
[Crossref] [PubMed]

Ophthalmology (3)

J. E. Grunwold, C. E. Riva, R. A. Stone, E. U. Keates, B. L. Petrig, “Retinal Autoregulation in Open-Angle Glaucoma,” Ophthalmology 91, 1690–1694 (1984).

H. A. Quigley, G. R. Dunkelberger, W. R. Green, “Chronic Human Glaucoma Causing Selectively Greater Loss of Large Optic Nerve Fibers,” Ophthalmology 95, 357–363 (1988).
[PubMed]

Y. Yamazaki, R. Lakowski, S. M. Drance, “A Comparison of the Blue Color Mechanism in High- and Low-Tension Glaucoma,” Ophthalmology 96, 12–15 (1989).
[PubMed]

Physica (1)

H. DeVries, “The Luminosity Curve of the Eye as Determined by Measurements with the Flickerphotometer,” Physica 14, 319–348 (1948).
[Crossref]

Prog. Retinal Res. (1)

R. Shapley, C. Enroth-Cugell, “Visual Adaptation and Retinal Gain Controls,” Prog. Retinal Res. 3, 263–346 (1984).
[Crossref]

Res. Clin. Forum (1)

S. L. Alvarez, K. B. Mills, “Spectral and Flicker Sensitivity in Ocular Hypertension and Glaucoma,” Res. Clin. Forum 7, 83–93 (1985).

Science (2)

D. H. Kelly, H. R. Wilson, “Human Flicker Sensitivity: Two Stages of Retinal Diffusion,” Science 202, 896–899 (1978).
[Crossref] [PubMed]

S. H. Goldberg, T. E. Frumkes, R. W. Nygaard, “Inhibitory Influence of Unstimulated Rods in the Human Retina: Evidence Provided by Examining Cone Flicker,” Science 221, 180–182 (1983).
[Crossref] [PubMed]

Surv. Ophthalmol. (1)

R. Z. Levene, “Low Tension Glaucoma: a Critical Review and New Material,” Surv. Ophthalmol. 24, 621–664 (1980).
[Crossref] [PubMed]

Trans. Am. Ophthalmol. Soc. (1)

R. L. Stamper, “The Effect of Glaucoma on Central Visual Function,” Trans. Am. Ophthalmol. Soc. 82, 792–826 (1984).
[PubMed]

Vision Res. (10)

C. F. Stromeyer, G. R. Cole, R. E. Kronauer, “Chromatic Suppression of Cone Inputs to the Luminance Flicker Mechanism,” Vision Res. 27, 1113–1137 (1987).
[Crossref] [PubMed]

At bleaching levels, steady-state cone quantum absorption asymptotes toward a maximum [see E. N. Pugh, J. D. Mollon, “A Theory of the pi-1 and pi-3 Color Mechanisms of Stiles,” Vision Res. 19, 293–312 (1979)], thus causing any intrareceptoral response compression to the test stimulus not alleviated by true adaptation [see M. M. Hayhoe et al., “The Time-Course of Multiplicative and Subtractive Adaptation Process,” Vision Res. 27, 1981–1996 (1987)] to also asymptote to a maximum. Therefore, spectrally opponent lateral antagonism is least adequate for background lights that bleach L cones but not M cones.
[Crossref] [PubMed]

N. J. Coletta, A. J. Adams, “Spatial Extent of Rod–Cone and Cone–Cone Interactions for Flicker Detection,” Vision Res. 26, 917–925 (1986).
[Crossref] [PubMed]

M. M. Hayhoe, M. V. Smith, “The Role of Spatial Filtering in Sensitivity Regulation,” Vision Res. 29, 457–469 (1989).
[Crossref] [PubMed]

A. Eisner, “Losses of Foveal Flicker Sensitivity During Dark Adaptation Following Extended Bleaches,” Vision Res. 29, 1401–1423 (1989).
[Crossref] [PubMed]

W. S. Geisler, “Evidence for the Equivalent-Background Hypothesis in Cones,” Vision Res. 19, 799–805 (1979).
[Crossref] [PubMed]

H. Heynen, L. Wachtmeister, D. van Norren, “Origin of the Oscillatory Potential in the Primate Retina,” Vision Res. 25, 1365–1373 (1985).
[Crossref] [PubMed]

G. B. Arden, T. E. Frumkes, “Stimulation of Rods can Increase Cone Flicker ERGs in Man,” Vision Res. 26, 711–721 (1986).
[Crossref] [PubMed]

D. H. Hood, “Suppression of the Frog’s Cone System in the Dark,” Vision Res. 12, 889–908 (1972).
[Crossref] [PubMed]

K. R. Alexander, G. A. Fishman, D. J. Derlacki, “Mechanisms of Rod–Cone Interaction: Evidence from Congenital Stationary Night Blindness,” Vision Res. 28, 575–583 (1988).
[Crossref] [PubMed]

Visual Neuroscience (1)

M. Conley, D. Fitzpatrick, “Morphology of retinogeniculate axons in the macaque,” Visual Neuroscience 2, 287–296 (1989).
[Crossref] [PubMed]

Other (35)

For a 570-nm test on the Wratten 33 background, Spearman r = 0.13. For a 480-nm test on the 480-nm background, Spearman r = 0.02.

For the 480-nm background considered separately, the association of PRFS with the combination of advanced age and relatively high IOP remained significant (p = 0.047). For the Wratten 33 background, the association remained significant (p = 0.037) only if the eye with an IOP equal to the median and with large IOP fluctuations was considered to have a relatively high IOP.

However, since nineteen of twenty-five people were judged to have suspicious or glaucomatous changes in one eye only and since flicker sensitivity was measured on Wratten 33 backgrounds for one eye only, the p-value of 0.087 should be considered to be an upper bound for the true p-value.

A history for use of any type of cardiovascular medication (antihypertension or cardiac vasodilator, inclusive) was not quite significantly associated for PRFS on the two backgrounds considered separately (p = 0.076 and p = 0.052 [two-sided tests]) for the 480-nm and Wratten 33 backgrounds, respectively.

All subjects with PRFS who were using cardiac vasodilators were using such medication regularly; two subjects without PRFS were using only nitroglycerine as needed. Of the six subjects with PRFS who were using antihypertension medication, three had used β-blockers. Of the eighteen subjects without PRFS who had used antihypertension medication, six had used β-blockers; two of these six had not used any other antihypertension medication.

The visual fields for five subjects were measured using the Humphrey 30-2 program; the visual fields for subjects-A and G were measured using Goldman manual perimetry.

A. Eisner, “Macular Function in Normal Aging: Loss of Flicker Sensitivity in Two Individuals,” Noninvasive Assessment of Visual Function, Technical Digest Series (Optical Society of America, Washington, DC, 1985), pp. TuA51–TuA54.

A. Eisner, S. A. Fleming, J. R. Samples, “Large Selective Losses of Flicker Sensitivity in Older People with Normal IOP and No History of Eye Disease,” Noninvasive Assessment of the Visual System, Technical Digest Series7 (Optical Society of America, Washington, DC, 1989), pp. 28–31.

G. Haegerstrom-Portnoy, A. J. Adams, B. Brown, A. Jampolsky, “Dynamics of Visual Adaptation are Altered in Vascular Disease,” in Advances in Diagnostic Visual Optics, G. M. Breinin, I. M. Siegel, Eds. (Springer-Verlag, New York, 1983).

Air puff tonometry was used rather than contact tonometry for screening purposes so that the short wavelength stimuli used for psychophysical testing could not cause the cornea to fluoresce.

All but 2 of the 109 subjects have retained 20/30 or better acuity in each eye; one eye of each of two subjects had an acuity loss to 20/40. All but 3 of the 109 subjects had IOP ≤ 22 in each eye at each session. Of the 109 subjects, 30 were male (of whom 18 were age 70 or older) and 79 were female (of whom 44 were age 70 or older). Twenty-six additional subjects who would have been due to return for testing 36 months after study entry were not tested at the time of the third session. These twenty-six subjects included nine who were ill and one who died. Two of these twenty-six subjects had PRFS at the first session. Two additional subjects who had PRFS at the first or second session were tested at the time of the third session, but with a battery of tests not identical to that of the regular third session.

Subjects adapted to the background for a minimum of 2 min prior to flicker threshold measurements. To measure flicker thresholds, a method of limits was used (0.04 log unit steps), in which the illuminance of a flickering test pedestal (100% modulation) was increased until the subject reported seeing flicker. If the examiner judged the flicker thresholds to be systematically decreasing, measurements were taken until the thresholds appeared to stabilize, after which four additional measurements were taken. Flicker sensitivity was computed from the mean of (the last) four flicker threshold settings.

Eyes were dark adapted for at least 7 min between flicker sensitivity and absolute sensitivity measurements. Prior to use of the 480-nm background, S cone sensitivity had been measured on a 1000-td, 580-nm background.

On the Wratten 33 background, a fixation aid (cross hairs with a 4° central gap) was used to facilitate foveal testing. Subjects adapted to the Wratten 33 background for a minimum of 3 min prior to flicker threshold measurements. Flicker sensitivity measurements were preceded by a 25-min period of dark adaptation and subsequent scotopic testing in the parafovea. The dark adaptation period required for scotopic testing itself followed measurement of foveal (photopic) absolute sensitivity.

Corresponding thresholds to 3°, 160-ms flashes were also measured.

Irradiance levels were measured using an EG&G model 550 radiometer with the detector positioned near the exit pupil of the apparatus. These irradiance levels were used to compute photopic illuminances for narrowband stimuli. For broadband stimuli (the Wratten 33 background), photopic illuminance was computed using a two-step procedure. First, to measure the illuminance of the long wavelength light passed by the Wratten 33 filter, a Tektronix model J16 photometer with the J6505 red LED test probe attached was used in combination with a short wavelength blocking filter. Second, to measure the illuminance of the short wavelength component, the difference was computed of two measurements—that of the Wratten 33 background and that of the Wratten 33 background with its short wavelength component blocked—taken with the EG&G model 550 photometer (which does not correctly measure illuminances in the red). In addition, spectroradiometric measurements of broadband stimuli were obtained using an EG&G model 555-61M spectroradiometer. From these spectroradiometric readings, metamerism was computed using the Smith and Pokorny estimates of M and L cone spectral sensitivities. [V. C. Smith, J. Pokorny, “Appendix, Part III (1975),” in R. M. Boynton, Human Color VisionHolt, Rinehart and Winston, New York, p. 404]. Flicker rate was calibrated by feeding the radiometer signal to an oscilloscope. Any intersession variation of flicker rate was appreciably <0.8 Hz, which corresponds to the thickness of the oscilloscope trace at 20 Hz.

For one subject with a PRFS, who was tested only once, the grader was in effect unmasked. That subject was judged to have a glaucotomous optic nerve head.

For nine subjects considered normal, photographs could not be graded for both eyes for every session. One of these nine subjects had a PRFS and was not tested at the third session; for five other subjects, the first or second session photographs could not be graded for each eye, but all the other photographs were graded as normal. For the remaining three of nine subjects, a third session photograph could not be graded. These three subjects were considered normal because none of the twenty-seven subjects assigned a non-normal grade at the third session would have been assigned a normal grade on the basis of the first and second session photographs alone.

All four subjects with PRFS at a regularly scheduled testing session were later retested using the 480-nm background at one or more supplemental testing sessions. Subject D was tested at one supplemental testing session; flicker sensitivity was again normal in each eye. Subject A was tested at three supplemental sessions, with variable results: (i) normal flicker sensitivity in each eye, (ii) normal in one eye, but at the low end of the non-PRFS range in the fellow eye, and (iii) grossly reduced (about 9 standard deviations) in each eye. Subjects B and C were each tested at one supplemental session. Each had a PRFS in one eye, but normal flicker sensitivities in the fellow eye. However, following a change of test wavelength from 660 to 490 nm after ~10 min of testing, the flicker sensitivity of subject B became immeasurably low at all test wavelengths for as long as testing continued. Although flicker sensitivity became profoundly reduced, sensitivity for detection of the test stimuli changed little or not at all.

Of the six subjects with a PRFS (subjects E–J), five were later retested foveally using the Wratten 33 background at supplemental testing sessions. Stimulus history was not standardized at these supplemental sessions. At the supplemental sessions, subjects F and I had PRFS, the flicker sensitivity of subject J was at the low end of the non-PRFS range, and subjects E and G had normal flicker sensitivities. For subjects F and I, however, flicker sensitivities abruptly became normal, several minutes after having apparently stabilized at profoundly reduced levels. For both these subjects, flicker sensitivity became normal immediately following a change of test wavelength from 490 to 570 nm.

Like other subjects tested with the Wratten 33 background at supplemental sessions, the flicker sensitivity of subject A eventually became normal.

When the association of PRFS with age was evaluated separately for two backgrounds, the association with advanced age remained significant (p < 0.01) for the 480-nm background, and became marginally nonsignificant (p = 0.06) for the Wratten 33 background.

For subjects without PRFS, the normal age-related losses on Wratten 33 backgrounds were neither pronounced nor universal and did not become evident until about age 75–80. However, flicker sensitivity at 570 nm on the Wratten 33 background did decrease significantly with age foveally (Spearman r = −0.25, p < 0.01, one-sided test), but not parafoveally (Spearman r = −0.12). The twenty-one non-PRFS subjects for whom flicker sensitivity was greater parafoveally than foveally were significant older (mean age 73.4 yr) than the non-PRFS subjects for whom flicker sensitivity was greater foveally than parafoveally (mean age 70.3 yr) (p = 0.008, two-sided Mann-Whitney U test). This post hoc comparison indicates that the age-related decrease of flicker sensitivity (on the Wratten 33 background) is greater foveally than parafoveally, even though the straightforward comparison of foveal and parafoveal flicker sensitivities was not quite statistically significant (Spearman r of the difference = −0.16). For a 480-nm test on a 480-nm background, flicker sensitivity also decreased significantly with age (Spearman r = −0.31, p < 0.001), as did the difference between 20-Hz sensitivity and sensitivity to 160-ms flashes (Spearman r = −0.19, p < 0.05). However, for backgrounds that are much affected by age-related changes of preretinal absorption, as 480-nm backgrounds are, the difference between sensitivities at two temporal frequencies depends very much on the slopes of the TVI curves.

J. M. Enoch, C. R. Fitzgerald, E. C. Campos, “Retinal Receptive Field-Like Properties in Primary Open-Angle Glaucoma,” in Quantitative Layer-by-Layer Perimetry, (Grune & Stratton, New York, 1981), Chap. 6, pp. 168–194.

S. S. Hayreh, “Blood Supply of the Anterior Optic Nerve,” in The Glaucomas, Vol. I, R. Ritch, M. B. Shields, T. Krupin, Eds. (C.V. Mosby, St. Louis MO., 1989), pp. 133–161.

Subjects adapted to the different background light levels for a minimum of 3 min, except for backgrounds that immediately followed another background of similar illuminance (not more than 0.2 log units different), in which case the minimum adaptation time was 2 min. Flicker thresholds were almost always computed from the means of four settings. When threshold vs illuminance (TVI) curves were obtained, background illuminance was always increased, except sometimes when probing the ends of steep sections of TVI curves. When threshold vs wavelength (TVλ) curves were obtained, test wavelengths were presented in ascending order beginning with 540 nm, and then in descending order again beginning with 540 nm, and finally, again at 540 nm.

Weber’s law was found to hold for the one subject (SF) tested using long wavelength (640-nm) tests on 656-nm backgrounds incremented in 0.1 log unit steps of illuminance. For both subjects, Weber’s law was found to hold across a 0.44 log unit interval for long wavelength 20 min of arc diam tests on a long pass background. Thus, it is not the case that a fortuitous combination of steep, shallow, and negative slopes caused Weber’s law to appear to hold at long test wavelengths across a 0.75 log unit interval.

An alternative explanation for the spectrally dependent losses of (M-cone mediated) flicker sensitivity does not require any spectrally opponent effects. That is, the M-cone quantum absorption from flashed short wavelength tests may be large enough relative to the M-cone quantum absorption from long wavelength backgrounds to saturate the response of M cones. However, (a) flicker TVI curves measured with flashed stimuli on long wavelength backgrounds were found to be virtually identical to the corresponding flicker TVI curves measured with continuous stimuli (both subjects), while (b) at illuminances just dimmer than those associated with failures of Weber’s law, the time-averaged M cone quantum catch from a 540-nm test was found to be only ~7% that from a 656-nm background (for SF). At longer test wavelengths, the corresponding percentage is appreciably less. Therefore, the alternative explanation that ascribes the failure of Weber’s law entirely to intrareceptoral effects is unlikely to be correct.

R. M. Boynton, Human Color Vision (Holt, Rinehart & Winston, New York, 1979).

N. J. Coletta, U. Houston, College of Optometry; personal communication.

A. Eisner, “Flicker Sensitivity Losses in Dark Adaptation: Spatial Factors,” OSA Annual Meeting, 1988 Technical Digest Series, Vol. 13 (Optical Society of America, Washington, DC, 1988), p. 67.

J. E. Dowling, The Retina: an Approachable Part of the Brain (Belknap, Cambridge, MA, 1987).

A. Eisner, Good Samaritan Hospital and Medical Center, Portland, OR; unpublished observations.

Unreported data from the same subjects imply that PRFS also can depend on test size and on the interaction of test size with test wavelength. On the 480-nm backgrounds subject Z had a PRFS, the flicker sensitivities of subjects W and X were at the low end of the non-PRFS continuum, and the flicker sensitivities of subject Y were normal.

Virtually the same spectrally dependent reductions were found at each of two testing sessions for subject X. However, at the first of these two testing sessions, flicker sensitivity appeared to oscillate by more than a log unit for up to ~30 min before stabilizing, at which time the reported values were measured. At the second testing session, flicker sensitivity appeared to stabilize much sooner after onset of the adapting light.

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Figures (7)

Fig. 1
Fig. 1

Foveal flicker sensitivity to a 3°, 490-nm, 20-Hz test on a 6°, 1000-td, 480-nm background vs foveal absolute sensitivity to a 3°, 160-ms, 660-nm test. The crossed bars are range bars, derived from data from both eyes of all 154 subjects without PRFS. Solid symbols represent data from the two eyes of each of four subjects with PRFS. Data plotted immediately below the dashed line represent flicker sensitivities that were too low to be measurable. Data are from the first testing session, except for the downward pointing triangles, which are from the second testing session.

Fig. 2
Fig. 2

Foveal flicker sensitivity to a 1°, 570-nm, 20-Hz test on an 11°, 5800-td, Wratten 33 background vs foveal absolute sensitivity to a 1°, 160-ms, 660-nm test. Data are from the third testing session.

Fig. 3
Fig. 3

Solid dots represent foveal flicker sensitivity to a 1°, 570-nm, 20-Hz test on an 11°, 5800-td Wratten 33 background vs age. The × symbols on the abscissa represent the ages of those subjects with immeasurably low flicker sensitivities on a 480-nm background, at the session during which the flicker sensitivity deficits were first found. All other data are from the third testing session (including those of two subjects younger than age 63, who were initially enrolled prior to age 60 because they were spouses of subjects aged 60 and older at the time).

Fig. 4
Fig. 4

Solid dots represent IOP vs age. The + symbols represent data from subjects with PRFS on the 5800-td Wratten 33 background. The × symbols represent data from subjects with PRFS on the 1000-td, 480-nm background, averaged for each subject’s two eyes when both eyes had a PRFS (see Fig. 1). The vertical and horizontal lines represent median ages and IOP’s, respectively, for those subjects without PRFS. The circles represent subjects for whom the between-eye IOP difference fluctuated the most (top fifth percentile) between testing sessions (see text). All the data except that marked by × are from the third testing session (when several subjects had IOP > 22).

Fig. 5
Fig. 5

(a) Left: foveal flicker thresholds (18-Hz sinusoidal, 750-ms on-intervals interspersed by 1500-ms off-intervals, 1° diameter, 540-nm test) as a function of the illuminance of a long pass (Schott RG 645) 8° background. Solid lines have slopes of 1. The solid triangles connected to the data in (a) right represent data obtained while measuring flicker thresholds as functions of test wavelength. Subject SF. (a) Right: foveal flicker thresholds on a long wavelength (Schott RG 645) background as functions of test wavelength for two background illuminances, 4.12 td (downward pointing triangles) and 4.87 td (upward pointing triangles). The solid curve represents the Smith and Pokorny11 M cone function fitted to the data by minimizing the rms difference from 540 to 660 nm. The dotted curve represents the solid curve translated upward by 0.75 log units. Subject SF. (b) Left: same as (a) left, except for subject RH. (b) Right: same as (b) right, except for subject RH. (At most testing sessions the lower 640-nm datapoint for subject RH fell on the solid curve.)

Fig. 6
Fig. 6

(a) Left: circles represent foveal flicker thresholds (20-Hz square wave, uninterrupted presentation, 1° diameter, 540-nm test) as a function of the illuminance of a Wratten 33 background. The crossed symbols (×) represent thresholds for detection of the test spot. The arrow signifies the illuminance of the background used to test the elderly subjects. Subject SF. (a) Right: corresponds to Fig. 5(a) right, except that the M-cone function is fit by minimizing the rms error from 540 to 620 nm only, and the parameters are those of Fig. 6(a) left. The crossed symbols (+) represent detection thresholds. Subject SF. (b) Left: same as (a) left, except for subject RH. (b) Right: same as (a) right, except for subject RH.

Fig. 7
Fig. 7

Histograms of foveal flicker sensitivity for three different test wavelengths, 490, 570, and 660 nm, on a 5800-td Wratten 33 background. The three histograms are positioned so that means of each distribution are aligned vertically. Individual symbols represent data from the three low-tension glaucoma subjects for whom spectral dependency could be evaluated. Leftward horizontally pointing arrows signify immeasurably low flicker sensitivities. Data are from the first thirty-one subjects tested at the fourth regularly scheduled testing session.

Tables (2)

Tables Icon

Table I Clinical Data for Subjects with Profound Reductions of Flicker Sensitivity

Tables Icon

Table II Clinical Data for Both Eyes of Subjects with Well-Documented Low-Tension Glaucoma

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