Abstract

Cross-sectional psychophysical and electrophysiologic studies of aging indicate that visual function declines only slightly or not at all until age 50–60, at which time the decline in visual function rapidly accelerates. This accelerated loss of function may reflect an increased rate of natural cellular degradation, or it may reflect an increased proportion of subclinical pathology in the presumed normal older population. This paper provides a critical review of the changes in visual function that occur with age. The results of this review have implications for both the definition of age-matched control groups and for early detection of age-related pathology.

© 1987 Optical Society of America

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References

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  1. Macular Photocoagulation Study Group, “Argon Laser Photocoagulation for Senile Macular Degeneration,” Arch. Ophthalmol. 100, 912 (1982).
    [PubMed]
  2. W. Smiddy, S. Fine, “Prognosis of Patients with Bilateral Macular Drusen,” Ophthalmologica 91, 271 (1984).
  3. D. Greenburg, L. Branch, “A Review of Methodologic Issues Concerning Incidence and Prevalence Data of Visual Deterioration in Elders,” Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 279–296.
  4. F. Weymouth, “Effect of Age on Visual Acuity,” in Vision of the Aging Patient (Quinn and Borden, Rathway, NJ, 1960), pp. 37–62. The number of subjects studied in this report (1675) is only 15,000 fewer than Pitt24 gives the author credit for (16,675) in Pitt’s review of the data.
  5. J. Moreland, “Temporal Variation in Anomaloscope Equations,” Mod. Probl. Ophthalmol. 19, 167 (1978).
    [PubMed]
  6. S. Jani, “The Age Factor in Stereopsis Screening,” Am. J Optom. 43, 653 (1966).
    [CrossRef]
  7. C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
    [CrossRef] [PubMed]
  8. K. Knoblauch, F. Saunders, M. Kusuda, R. Hynes, M. Podgor, K. E. Higgins, F. M. de Monasterio, “Age and Illuminance Effects in the Farnsworth-Munsell 100 Hue Test,” Appl. Opt. 26, 1441 (1987).
    [CrossRef] [PubMed]
  9. A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
    [PubMed]
  10. J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
    [CrossRef] [PubMed]
  11. G. Celesia, R. Daly, “Effects of Aging on Visual Evoked Responses,” Arch. Neurol. 34, 403 (1977).
    [CrossRef] [PubMed]
  12. S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
    [CrossRef]
  13. G. Celesia, “Evoked Potential Techniques in the Evaluation of Visual Function,” J. Clin. Neurophysiol. 1, 55 (1984).
    [CrossRef] [PubMed]
  14. K. Chiappa, Evoked Potentials in Clinical Medicine (Raven Press, New York, 1983).
  15. P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
    [CrossRef] [PubMed]
  16. D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
    [CrossRef]
  17. Age 50 is an approximation determined in part by the specifics of the reported data. Actual critical ages seem to vary between 45 and 60 yr. Our hypothesis does not assume that there is one critical age which is the same for every measure of visual function, rather that these critical ages which appear to all to occur at about the same time as the frequency of age-related pathology in the population becomes significant.
  18. R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
    [CrossRef]
  19. R. Applegate, A. Adams, J. Cavender, F. Zisman, “Early Color Vision Changes in Age-Related Maculopathy,” Appl. Opt. 26, 1458 (1987).
    [CrossRef] [PubMed]
  20. J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
    [CrossRef] [PubMed]
  21. R. Weale, “Senile Changes in Visual Acuity,” So. Trans. Ophthalmol. Soc. UK 95, 36 (1975).
  22. J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” in Technical Digest, Topical Meeting on Noninvasive Assessment of the Visual System (Optical Society of America, Washington, DC, 1986), paper WA1.
  23. H. Leibowitz et al., “The Framingham Eye Study Monogram,” Surv. Ophthalmol. Suppl. 24, 335 (1980).
  24. D. Pitts, “The Effects of Aging on Selected Visual Functions: Dark Adaptation, Visual Acuity, Stereopsis, and Brightness Contrast,” in Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 131–159.

1987 (2)

1986 (2)

A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
[PubMed]

J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
[CrossRef] [PubMed]

1985 (1)

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

1984 (2)

G. Celesia, “Evoked Potential Techniques in the Evaluation of Visual Function,” J. Clin. Neurophysiol. 1, 55 (1984).
[CrossRef] [PubMed]

W. Smiddy, S. Fine, “Prognosis of Patients with Bilateral Macular Drusen,” Ophthalmologica 91, 271 (1984).

1983 (1)

C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
[CrossRef] [PubMed]

1982 (1)

Macular Photocoagulation Study Group, “Argon Laser Photocoagulation for Senile Macular Degeneration,” Arch. Ophthalmol. 100, 912 (1982).
[PubMed]

1981 (1)

S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
[CrossRef]

1980 (1)

H. Leibowitz et al., “The Framingham Eye Study Monogram,” Surv. Ophthalmol. Suppl. 24, 335 (1980).

1978 (1)

J. Moreland, “Temporal Variation in Anomaloscope Equations,” Mod. Probl. Ophthalmol. 19, 167 (1978).
[PubMed]

1977 (2)

G. Celesia, R. Daly, “Effects of Aging on Visual Evoked Responses,” Arch. Neurol. 34, 403 (1977).
[CrossRef] [PubMed]

D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
[CrossRef]

1975 (2)

P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
[CrossRef] [PubMed]

R. Weale, “Senile Changes in Visual Acuity,” So. Trans. Ophthalmol. Soc. UK 95, 36 (1975).

1972 (1)

R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
[CrossRef]

1966 (1)

S. Jani, “The Age Factor in Stereopsis Screening,” Am. J Optom. 43, 653 (1966).
[CrossRef]

Adams, A.

Alvarado, J.

J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
[CrossRef] [PubMed]

Applegate, R.

Aspinall, P.

R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
[CrossRef]

Asselman, P.

P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
[CrossRef] [PubMed]

Branch, L.

D. Greenburg, L. Branch, “A Review of Methodologic Issues Concerning Incidence and Prevalence Data of Visual Deterioration in Elders,” Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 279–296.

Cavender, J.

Celesia, G.

G. Celesia, “Evoked Potential Techniques in the Evaluation of Visual Function,” J. Clin. Neurophysiol. 1, 55 (1984).
[CrossRef] [PubMed]

G. Celesia, R. Daly, “Effects of Aging on Visual Evoked Responses,” Arch. Neurol. 34, 403 (1977).
[CrossRef] [PubMed]

Chadwick, D.

P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
[CrossRef] [PubMed]

Chiappa, K.

K. Chiappa, Evoked Potentials in Clinical Medicine (Raven Press, New York, 1983).

Daly, R.

G. Celesia, R. Daly, “Effects of Aging on Visual Evoked Responses,” Arch. Neurol. 34, 403 (1977).
[CrossRef] [PubMed]

de Monasterio, F. M.

Fine, S.

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

W. Smiddy, S. Fine, “Prognosis of Patients with Bilateral Macular Drusen,” Ophthalmologica 91, 271 (1984).

Finkelstein, D.

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

Flammer, J.

A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
[PubMed]

Freund, H.

D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
[CrossRef]

Greenburg, D.

D. Greenburg, L. Branch, “A Review of Methodologic Issues Concerning Incidence and Prevalence Data of Visual Deterioration in Elders,” Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 279–296.

Haas, A.

A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
[PubMed]

Henerici, D.

D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
[CrossRef]

Higgins, K. E.

Hynes, R.

Jaffe, J.

J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
[CrossRef] [PubMed]

Jani, S.

S. Jani, “The Age Factor in Stereopsis Screening,” Am. J Optom. 43, 653 (1966).
[CrossRef]

Johnson, M. A.

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

Juster, R.

J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
[CrossRef] [PubMed]

Kinnear, P.

R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
[CrossRef]

Knoblauch, K.

Kusuda, M.

Lakowsky, R.

R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
[CrossRef]

Leibowitz, H.

H. Leibowitz et al., “The Framingham Eye Study Monogram,” Surv. Ophthalmol. Suppl. 24, 335 (1980).

Lutze, M.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” in Technical Digest, Topical Meeting on Noninvasive Assessment of the Visual System (Optical Society of America, Washington, DC, 1986), paper WA1.

Marsden, C.

P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
[CrossRef] [PubMed]

Massof, R. W.

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

Moreland, J.

J. Moreland, “Temporal Variation in Anomaloscope Equations,” Mod. Probl. Ophthalmol. 19, 167 (1978).
[PubMed]

Moskowitz, A.

S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
[CrossRef]

Owsley, C.

C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
[CrossRef] [PubMed]

Pitts, D.

D. Pitts, “The Effects of Aging on Selected Visual Functions: Dark Adaptation, Visual Acuity, Stereopsis, and Brightness Contrast,” in Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 131–159.

Podgor, M.

Pokorny, J.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” in Technical Digest, Topical Meeting on Noninvasive Assessment of the Visual System (Optical Society of America, Washington, DC, 1986), paper WA1.

Saunders, F.

Schneider, U.

A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
[PubMed]

Sekular, R.

C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
[CrossRef] [PubMed]

Siemsen, D.

C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
[CrossRef] [PubMed]

Smiddy, W.

W. Smiddy, S. Fine, “Prognosis of Patients with Bilateral Macular Drusen,” Ophthalmologica 91, 271 (1984).

Smith, V. C.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” in Technical Digest, Topical Meeting on Noninvasive Assessment of the Visual System (Optical Society of America, Washington, DC, 1986), paper WA1.

Sokol, S.

S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
[CrossRef]

Sunness, J. S.

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

Towle, V.

S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
[CrossRef]

Weale, R.

R. Weale, “Senile Changes in Visual Acuity,” So. Trans. Ophthalmol. Soc. UK 95, 36 (1975).

Wenzel, D.

D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
[CrossRef]

Weymouth, F.

F. Weymouth, “Effect of Age on Visual Acuity,” in Vision of the Aging Patient (Quinn and Borden, Rathway, NJ, 1960), pp. 37–62. The number of subjects studied in this report (1675) is only 15,000 fewer than Pitt24 gives the author credit for (16,675) in Pitt’s review of the data.

Zisman, F.

Am J Ophthalmol. (1)

A. Haas, J. Flammer, U. Schneider, “Influence of Age on Visual Fields of Normal Subjects,” Am J Ophthalmol. 101, 199 (1986).
[PubMed]

Am. J Optom. (1)

S. Jani, “The Age Factor in Stereopsis Screening,” Am. J Optom. 43, 653 (1966).
[CrossRef]

Appl. Opt. (2)

Arch. Neurol. (1)

G. Celesia, R. Daly, “Effects of Aging on Visual Evoked Responses,” Arch. Neurol. 34, 403 (1977).
[CrossRef] [PubMed]

Arch. Ophthalmol. (3)

J. Jaffe, J. Alvarado, R. Juster, “Age-Related Changes of the Normal Visual Field,” Arch. Ophthalmol. 104, 1021 (1986).
[CrossRef] [PubMed]

Macular Photocoagulation Study Group, “Argon Laser Photocoagulation for Senile Macular Degeneration,” Arch. Ophthalmol. 100, 912 (1982).
[PubMed]

J. S. Sunness, R. W. Massof, M. A. Johnson, D. Finkelstein, S. Fine, “Peripheral Retinal Function in Age-Related Macular Degeneration,” Arch. Ophthalmol. 103, 811 (1985).
[CrossRef] [PubMed]

Brain (2)

P. Asselman, D. Chadwick, C. Marsden, “Visual Evoked Responses in the Diagnosis and Management of Patients Suspected of Multiple Sclerosis,” Brain 98, 261 (1975).
[CrossRef] [PubMed]

D. Henerici, D. Wenzel, H. Freund, “The Comparison of Small Size Rectangle and Checkerboard Stimulation for the Evaluation of Delayed Visual Evoked Responses in Patients Suspected of Multiple Sclerosis,” Brain 100, 119 (1977).
[CrossRef]

EEG Clin. Neurol. (1)

S. Sokol, A. Moskowitz, V. Towle, “Age-Related Changes in the Latency of Visual Evoked Potentials: Influence of Check Size,” EEG Clin. Neurol. 51, 559 (1981).
[CrossRef]

J. Clin. Neurophysiol. (1)

G. Celesia, “Evoked Potential Techniques in the Evaluation of Visual Function,” J. Clin. Neurophysiol. 1, 55 (1984).
[CrossRef] [PubMed]

Mod. Probl. Ophthalmol. (1)

J. Moreland, “Temporal Variation in Anomaloscope Equations,” Mod. Probl. Ophthalmol. 19, 167 (1978).
[PubMed]

Ophthalmol. Res. (1)

R. Lakowsky, P. Aspinall, P. Kinnear, “Association Between Color Vision Losses and Diabetes Mellitus,” Ophthalmol. Res. 4, 145 (1972).
[CrossRef]

Ophthalmologica (1)

W. Smiddy, S. Fine, “Prognosis of Patients with Bilateral Macular Drusen,” Ophthalmologica 91, 271 (1984).

So. Trans. Ophthalmol. Soc. UK (1)

R. Weale, “Senile Changes in Visual Acuity,” So. Trans. Ophthalmol. Soc. UK 95, 36 (1975).

Surv. Ophthalmol. Suppl. (1)

H. Leibowitz et al., “The Framingham Eye Study Monogram,” Surv. Ophthalmol. Suppl. 24, 335 (1980).

Vision Res. (1)

C. Owsley, R. Sekular, D. Siemsen, “Contrast Sensitivity Throughout Adulthood,” Vision Res. 23, 689 (1983).
[CrossRef] [PubMed]

Other (6)

D. Greenburg, L. Branch, “A Review of Methodologic Issues Concerning Incidence and Prevalence Data of Visual Deterioration in Elders,” Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 279–296.

F. Weymouth, “Effect of Age on Visual Acuity,” in Vision of the Aging Patient (Quinn and Borden, Rathway, NJ, 1960), pp. 37–62. The number of subjects studied in this report (1675) is only 15,000 fewer than Pitt24 gives the author credit for (16,675) in Pitt’s review of the data.

Age 50 is an approximation determined in part by the specifics of the reported data. Actual critical ages seem to vary between 45 and 60 yr. Our hypothesis does not assume that there is one critical age which is the same for every measure of visual function, rather that these critical ages which appear to all to occur at about the same time as the frequency of age-related pathology in the population becomes significant.

K. Chiappa, Evoked Potentials in Clinical Medicine (Raven Press, New York, 1983).

D. Pitts, “The Effects of Aging on Selected Visual Functions: Dark Adaptation, Visual Acuity, Stereopsis, and Brightness Contrast,” in Aging and Human Visual Function (Alan R. Liss, New York, 1982), pp. 131–159.

J. Pokorny, V. C. Smith, M. Lutze, “Aging of the Human Lens,” in Technical Digest, Topical Meeting on Noninvasive Assessment of the Visual System (Optical Society of America, Washington, DC, 1986), paper WA1.

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Figures (6)

Fig. 1
Fig. 1

Change in visual function with aging. The dashed vertical line is drawn at 50 yr: (A) Snellen acuity data from Weymouth4 is plotted in terms of the log relative minimum angle of resolution. The age of onset of acuity loss is ~60, ~10 yr later than the time at which other functional measures start to degrade. This apparent inconsistency may be due in part to the conservative definition of 20/20 as normal in this study. (B) The log percentage of normal individuals who failed the diastereo (stereoacuity) test as a function of the age of the subject (from Jani6). Subjects were selected to have normal (20/40 or better) visual acuity. (C) The shift in the log blue/green color match as a function of age (data from Moreland5). (D) Log VEP P1 latencies from studies by Asselman et al.,15 Celesia and Daly,11 Sokol et al.,12 and Celesia.13 The slightly earlier age of onset of increased P1 latency in Sokol’s data may be attributable to his use of a check size 12 min of arc that was smaller than those used by the other authors.

Fig. 2
Fig. 2

(A) Jaffe et al.’s11 data on mean perimetric increment threshold elevation, measured using an Octopus perimeter. The boldface line is the regression line fit to all the data, while the other lines are regression lines fit to the subsets of data that cluster above and below the original regression line. The equation of the line fit to all the data is Y = −0.078X + 28.8, and the Pearson correlation coefficient is 0.62. If only the data that are clustered above the boldface line are considered, however, the data from older subjects are more readily seen to be an extrapolation of the younger normal data. The regression line fit to these data may represent the decline in function in healthy normal individuals. The equation for this line is Y = −0.057X + 28.8, and the correlation coefficient is 0.84. The data clustered below the original regression line may represent data from normal subjects who have subclinical pathology. The equation for this line is Y = −0.067X + 26.5, and the correlation coefficient is 0.88. (B) illustrates the bimodality of the distribution of data obtained from subjects > 50 yr old.

Fig. 3
Fig. 3

Change in color discrimination as a function of age (from Knoblauch et al.8). Data were collected at an illuminance of 18 lux. Regression lines shown were fit to the young (before 45 yr) and old (45 yr and older) distributions, respectively. The equation of the regression line fit to all the data (Y = 0.016X + 0.285) has the same slope as the equation of the regression line fit to the data from the older individuals only (Y = 0.016X + 0.337) but is substantially different from the equation of the line fit to the data from the younger subjects only (Y = 0.003X + 0.647). The Pearson correlation coefficients were 0.79 for the total data group, 0.46 for the data from the older subjects, and 0.11 for the data from the younger subjects. The small correlation obtained from the younger age group accurately reflects the lack of, or very small, effect of age on color discrimination in individuals under 45.

Fig. 4
Fig. 4

Sokol et al.’s12 VEP P1 latencies for normal subjects of different ages for a 12 min of arc check size. The boldface line is our calculation of the linear regression to the data. The equation of this line is Y = 0.28X + 104.7, and the Pearson correlation coefficient is 0.65. Because the data appear to cluster into two distinct distributions, we separately analyzed the latency data measured in subjects younger than 45 from subjects older than 45. Regression lines fit to these two groups are shown. The data from the subjects younger than 45 were not correlated with age. The equation of the regression line fit to these data is Y = 114.2, and the Pearson correlation coefficient is 0.06. The data from the older group show a much better correlation with age. The equation of the regression line that we calculated is Y = 0.39X + 98.2, and the correlation coefficient is 0.52.

Fig. 5
Fig. 5

(A) Change of log contrast thresholds for sinusiodal gratings having spatial frequencies of 2.0, 4.0, 8.0, and 16.0 cycles/degree as a function of age (data from Owsley et al.7). The slope of the increase in thresholds increases at about ages 40–50, depending on the spatial frequency of the grating. Intersubject variability in the data increases substantially at about the same time (B). The mean standard deviations of the data collected at these four spatial frequencies are also plotted in this figure.

Fig. 6
Fig. 6

Prevalence of cataract, glaucoma, diabetic retinopathy, and age-related macular degeneration in people between 55 and 84 yr. (data from the Framingham Eye Study23).

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