Abstract

We used a fast psychophysical procedure to determine the wave-front aberrations of the human eye in vivo. We measured the angular deviation of light rays entering the eye at different pupillary locations by aligning an image of a point source entering the pupil at different locations to the image of a fixation cross entering the pupil at a fixed location. We fitted the data to a Zernike series to reconstruct the wave-front aberrations of the pupil. With this technique the repeatability of the measurement of the individual coefficients was 0.019 µm. The standard deviation of the overall wave-height estimation across the pupil is less than 0.3 µm. Since this technique does not require the administration of pharmacological agents to dilate the pupil, we were able to measure the changes in the aberrations of the eye during accommodation. We found that administration of even a mild dilating agent causes a change in the aberration structure of the eye.

© 1998 Optical Society of America

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References

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  1. P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
    [CrossRef] [PubMed]
  2. P. Artal, R. Navarro, “Monochromatic modulation transfer function of the human eye for different pupil diameters: an analytical expression,” J. Opt. Soc. Am. A 11, 246–249 (1994).
    [CrossRef]
  3. F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).
  4. J. A. M. Jennings, W. Charman, “An analytical approximation of the transfer function of the eye,” Br. J. Physiol. Opt. 29, 64–72 (1974).
  5. R. Navarro, M. A. Losada, “Phase transfer and point-spread function of the human eye determined by a new asymmetric double-pass method,” J. Opt. Soc. Am. A 12, 2385–2392 (1995).
    [CrossRef]
  6. C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
    [CrossRef]
  7. A. Glaser, M. C. W. Campbell, “Presbyopia and the optical changes in the human crystalline lens with age,” Vision Res. 38, 209–229 (1998).
    [CrossRef]
  8. J. Koretz, C. Cook, J. Kuszaks, “The zones of discontinuity in the human lens: development and distribution with age,” Vision Res. 34, 2955–2962 (1994).
    [CrossRef] [PubMed]
  9. P. Artal, J. Santamaria, J. Bescos, “Retrieval of wave aberration of human eyes from actual point-spread-function data,” J. Opt. Soc. Am. A 5, 1201–1206 (1988).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  11. R. Navarro, M. A. Losada, “Aberrations and relative efficiency of light pencils in the living human eye,” Optom. Vision Sci. 74, 540–547 (1997).
    [CrossRef]
  12. J. Liang, B. Grimm, S. Goetz, J. F. Bille, “Objective measurements of wave aberrations of the human eye with the use of a Hartmann–Shack wave-front sensor,” J. Opt. Soc. Am. A 11, 1949–1957 (1994).
    [CrossRef]
  13. J. Liang, D. R. Williams, “Aberrations and retinal image quality of the normal human eye,” J. Opt. Soc. Am. A 14, 2873–2883 (1997).
    [CrossRef]
  14. H. C. Howland, B. Howland, “A subjective method for the measurement of monochromatic aberrations of the eye,” J. Opt. Soc. Am. 67, 1508–1518 (1977).
    [CrossRef] [PubMed]
  15. M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
    [CrossRef]
  16. R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
    [CrossRef] [PubMed]
  17. W. N. Charman, “Wavefront aberration of the eye: a review,” Optom. Vision Sci. 68, 574–583 (1991).
    [CrossRef]
  18. R. H. Webb, C. M. Penney, K. P. Thompson, “Measurement of ocular wavefront distortion with a spatially resolved refractometer,” Appl. Opt. 31, 3678–3686 (1992).
    [CrossRef] [PubMed]
  19. A. Ivanoff, “Sur une methode de mésure des aberrations chromatique et spheriques de l’oeil en lumière dirigée,” C. R. Hebd. Seances Acad. Sci. 231, 562–528 (1946).
  20. A. Ivanoff, “About the spherical aberration of the eye,” J. Opt. Soc. Am. 46, 901–903 (1953).
  21. C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).
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  26. We used the convention described by Malacara25 for determining which coefficient represents each polynomial. In this system, defocus is represented by the fourth coefficient, first-order astigmatism by a combination of the third and the fifth, coma by the seventh and the eighth, and first-order spherical aberration by the twelfth.
  27. M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, UK, 1983).
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  30. R. H. Webb, “Zernike polynomial description of ophthalmic surfaces,” Ophthalmic Visual Opt. 3, 38–41 (1992).
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    [CrossRef]
  32. These measurements are traditionally adjusted with a Gram–Schmidt procedure (see Ref. 25). However, we have not found this necessary because we are not using a point sampling procedure (see results).
  33. This is true for all terms that we used except the 12th term, which has a lower peak-to-peak amplitude.
  34. D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
    [CrossRef] [PubMed]
  35. B. Gilmartin, R. E. Hogan, “The relationship between tonic accommodation and ciliary muscle innervation,” Invest. Ophthalmol. Visual Sci. 26, 1024–1028 (1985).

1998

A. Glaser, M. C. W. Campbell, “Presbyopia and the optical changes in the human crystalline lens with age,” Vision Res. 38, 209–229 (1998).
[CrossRef]

1997

R. Navarro, M. A. Losada, “Aberrations and relative efficiency of light pencils in the living human eye,” Optom. Vision Sci. 74, 540–547 (1997).
[CrossRef]

J. Liang, D. R. Williams, “Aberrations and retinal image quality of the normal human eye,” J. Opt. Soc. Am. A 14, 2873–2883 (1997).
[CrossRef]

1996

R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
[CrossRef] [PubMed]

P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
[CrossRef] [PubMed]

1995

1994

1992

1991

W. N. Charman, “Wavefront aberration of the eye: a review,” Optom. Vision Sci. 68, 574–583 (1991).
[CrossRef]

1990

M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
[CrossRef]

1988

1985

B. Gilmartin, R. E. Hogan, “The relationship between tonic accommodation and ciliary muscle innervation,” Invest. Ophthalmol. Visual Sci. 26, 1024–1028 (1985).

1984

1981

1980

1979

1977

1974

J. A. M. Jennings, W. Charman, “An analytical approximation of the transfer function of the eye,” Br. J. Physiol. Opt. 29, 64–72 (1974).

1966

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

1953

1946

A. Ivanoff, “Sur une methode de mésure des aberrations chromatique et spheriques de l’oeil en lumière dirigée,” C. R. Hebd. Seances Acad. Sci. 231, 562–528 (1946).

Artal, P.

Atchison, D. A.

R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
[CrossRef] [PubMed]

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Bescos, J.

Bille, J. F.

Born, M.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, UK, 1983).

Bradley, L. A.

R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
[CrossRef] [PubMed]

Campbell, F. W.

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

Campbell, M. C. W.

A. Glaser, M. C. W. Campbell, “Presbyopia and the optical changes in the human crystalline lens with age,” Vision Res. 38, 209–229 (1998).
[CrossRef]

M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
[CrossRef]

Charman, W.

J. A. M. Jennings, W. Charman, “An analytical approximation of the transfer function of the eye,” Br. J. Physiol. Opt. 29, 64–72 (1974).

Charman, W. N.

Christensen, J.

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Collins, M. J.

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Cook, C.

J. Koretz, C. Cook, J. Kuszaks, “The zones of discontinuity in the human lens: development and distribution with age,” Vision Res. 34, 2955–2962 (1994).
[CrossRef] [PubMed]

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

Cubalachini, R.

Gilmartin, B.

B. Gilmartin, R. E. Hogan, “The relationship between tonic accommodation and ciliary muscle innervation,” Invest. Ophthalmol. Visual Sci. 26, 1024–1028 (1985).

Glaser, A.

A. Glaser, M. C. W. Campbell, “Presbyopia and the optical changes in the human crystalline lens with age,” Vision Res. 38, 209–229 (1998).
[CrossRef]

Goetz, S.

Green, D. G.

P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
[CrossRef] [PubMed]

Grievenkamp, J. E.

Grimm, B.

Gubisch, R. W.

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

Harrison, E. M.

M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
[CrossRef]

Herrman, J.

Hogan, R. E.

B. Gilmartin, R. E. Hogan, “The relationship between tonic accommodation and ciliary muscle innervation,” Invest. Ophthalmol. Visual Sci. 26, 1024–1028 (1985).

Howland, B.

Howland, H. C.

Hyun, J.

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

Iglesias, I.

P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
[CrossRef] [PubMed]

Ivanoff, A.

A. Ivanoff, “About the spherical aberration of the eye,” J. Opt. Soc. Am. 46, 901–903 (1953).

A. Ivanoff, “Sur une methode de mésure des aberrations chromatique et spheriques de l’oeil en lumière dirigée,” C. R. Hebd. Seances Acad. Sci. 231, 562–528 (1946).

Jennings, J. A. M.

J. A. M. Jennings, W. Charman, “An analytical approximation of the transfer function of the eye,” Br. J. Physiol. Opt. 29, 64–72 (1974).

Kaufman, P.

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

Koretz, J.

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

J. Koretz, C. Cook, J. Kuszaks, “The zones of discontinuity in the human lens: development and distribution with age,” Vision Res. 34, 2955–2962 (1994).
[CrossRef] [PubMed]

Kuszaks, J.

J. Koretz, C. Cook, J. Kuszaks, “The zones of discontinuity in the human lens: development and distribution with age,” Vision Res. 34, 2955–2962 (1994).
[CrossRef] [PubMed]

Liang, J.

Losada, M. A.

R. Navarro, M. A. Losada, “Aberrations and relative efficiency of light pencils in the living human eye,” Optom. Vision Sci. 74, 540–547 (1997).
[CrossRef]

R. Navarro, M. A. Losada, “Phase transfer and point-spread function of the human eye determined by a new asymmetric double-pass method,” J. Opt. Soc. Am. A 12, 2385–2392 (1995).
[CrossRef]

Mahajan, V. N.

Malacara, D.

D. Malacara, Optical Shop Testing (Wiley, New York, 1992).

Marcos, S.

P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
[CrossRef] [PubMed]

Miller, J. M.

Navarro, R.

Penney, C. M.

R. H. Webb, C. M. Penney, K. P. Thompson, “Measurement of ocular wavefront distortion with a spatially resolved refractometer,” Appl. Opt. 31, 3678–3686 (1992).
[CrossRef] [PubMed]

C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).

Pfahnl, A.

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

Santamaria, J.

Schwiegerling, J.

Silva, D. E.

Simonet, P.

M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
[CrossRef]

Southwell, W.

Thompson, K. P.

R. H. Webb, C. M. Penney, K. P. Thompson, “Measurement of ocular wavefront distortion with a spatially resolved refractometer,” Appl. Opt. 31, 3678–3686 (1992).
[CrossRef] [PubMed]

C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).

Tieman, J. T.

C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).

Walsh, G.

Wang, J. Y.

Waterworth, M. D.

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Webb, R. H.

R. H. Webb, “Zernike polynomial description of ophthalmic surfaces,” Ophthalmic Visual Opt. 3, 38–41 (1992).

R. H. Webb, C. M. Penney, K. P. Thompson, “Measurement of ocular wavefront distortion with a spatially resolved refractometer,” Appl. Opt. 31, 3678–3686 (1992).
[CrossRef] [PubMed]

C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).

Wildsoet, C. F.

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Williams, D. R.

Wolf, E.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, UK, 1983).

Woods, R.

R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
[CrossRef] [PubMed]

Appl. Opt.

Br. J. Physiol. Opt.

J. A. M. Jennings, W. Charman, “An analytical approximation of the transfer function of the eye,” Br. J. Physiol. Opt. 29, 64–72 (1974).

C. R. Hebd. Seances Acad. Sci.

A. Ivanoff, “Sur une methode de mésure des aberrations chromatique et spheriques de l’oeil en lumière dirigée,” C. R. Hebd. Seances Acad. Sci. 231, 562–528 (1946).

Invest. Ophthalmol. Visual Sci.

B. Gilmartin, R. E. Hogan, “The relationship between tonic accommodation and ciliary muscle innervation,” Invest. Ophthalmol. Visual Sci. 26, 1024–1028 (1985).

J. Opt. Soc. Am.

J. Opt. Soc. Am. A

J. Physiol. (London)

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

Ophthalmic Visual Opt.

R. H. Webb, “Zernike polynomial description of ophthalmic surfaces,” Ophthalmic Visual Opt. 3, 38–41 (1992).

Optom. Vision Sci.

W. N. Charman, “Wavefront aberration of the eye: a review,” Optom. Vision Sci. 68, 574–583 (1991).
[CrossRef]

R. Navarro, M. A. Losada, “Aberrations and relative efficiency of light pencils in the living human eye,” Optom. Vision Sci. 74, 540–547 (1997).
[CrossRef]

Vision Res.

C. Cook, J. Koretz, A. Pfahnl, J. Hyun, P. Kaufman, “Aging of the human crystalline lens and anterior segment,” Vision Res. 34, 1945–2954 (1994).
[CrossRef]

A. Glaser, M. C. W. Campbell, “Presbyopia and the optical changes in the human crystalline lens with age,” Vision Res. 38, 209–229 (1998).
[CrossRef]

J. Koretz, C. Cook, J. Kuszaks, “The zones of discontinuity in the human lens: development and distribution with age,” Vision Res. 34, 2955–2962 (1994).
[CrossRef] [PubMed]

M. C. W. Campbell, E. M. Harrison, P. Simonet, “Psychophysical measurement of the blur of the retina due to optical aberrations of the eye,” Vision Res. 30, 1587–1602 (1990).
[CrossRef]

R. Woods, L. A. Bradley, D. A. Atchison, “Monocular diplopia caused by ocular aberrations and hyperopic defocus,” Vision Res. 36, 3597–3606 (1996).
[CrossRef] [PubMed]

P. Artal, S. Marcos, I. Iglesias, D. G. Green, “Optical modulation transfer function and contrast sensitivity with decentered small pupils in the human eye,” Vision Res. 36, 3575–3586 (1996).
[CrossRef] [PubMed]

D. A. Atchison, M. J. Collins, C. F. Wildsoet, J. Christensen, M. D. Waterworth, “Measurement of monochromatic ocular aberrations of human eyes as a function of accommodation by the Howland aberroscope technique,” Vision Res. 35, 313–323 (1995).
[CrossRef] [PubMed]

Other

These measurements are traditionally adjusted with a Gram–Schmidt procedure (see Ref. 25). However, we have not found this necessary because we are not using a point sampling procedure (see results).

This is true for all terms that we used except the 12th term, which has a lower peak-to-peak amplitude.

D. Malacara, Optical Shop Testing (Wiley, New York, 1992).

We used the convention described by Malacara25 for determining which coefficient represents each polynomial. In this system, defocus is represented by the fourth coefficient, first-order astigmatism by a combination of the third and the fifth, coma by the seventh and the eighth, and first-order spherical aberration by the twelfth.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, UK, 1983).

C. M. Penney, R. H. Webb, J. T. Tieman, K. P. Thompson, “Spatially resolved objective refractometer,” U.S. patent5,258,791 (November2, 1993).

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Figures (7)

Fig. 1
Fig. 1

Schematic diagram of the spatially resolved refractometer. It is a three-channel Maxwellian view system (see text), which has separate channels for the test, the fixation stimulus, and pupil monitoring. A Badal optometer (focusing block) allows the experimenter to change the refractive state of the test and reference channels together, without changing the location of the pupil (P0) conjugate planes (P1, P1, P2, P2). Retinol (R0) conjugate planes are located at positions R1, R2, R2, and R3. (Other abbreviations are defined in the text.) All lenses have a focal length of 150 mm and a diameter of 35 mm.

Fig. 2
Fig. 2

Example of the results of the numerical simulations of the effect of high-order aberrations on the measured Zernike coefficients. Solid curve, values entered into the simulation program for Zernike coefficients 3–35. Filled circles, predicted measurements. We added sufficient high-order aberrations (coefficients from 36 to 54) to decrease the Strehl ratio to 0.54.

Fig. 3
Fig. 3

a, Data collected from the spatially resolved refractometer with a CCD camera in place of the eye. Data are shown for three different levels of defocus:-1, 0, and 1.3 D. We have not plotted either piston (the zero-order Zernike term) or tilt (the first-order Zernike terms). The horizontal line near each data point represents plus or minus one standard deviation of the measurements. b, Measured angle of a 2-D cylindrical lens as a function of its actual angle. Horizontal lines, plus or minus one standard deviation of the measurements.

Fig. 4
Fig. 4

a, Zernike coefficients estimated from five successive runs in a single session from subject S1. The filled circles and the solid curve plot the mean of the five runs. The error bars indicate the range of the coefficient estimates for the five runs. This subject’s aberrations were dominated by coma (Zernike terms 7 and 8) as well as by other terms that do not have classical optical equivalents. The average standard deviation for the 3rd through the 10th coefficients was 0.48 µm. b, Standard deviation of the wave-height estimates obtained from five consecutive runs collected on a single day (observer S1). The standard deviation of the wave height was first computed for each point in the pupil. These data were then radially averaged, giving the standard deviation as a distance from the center of the pupil. At the edges of the pupil the standard deviation estimates increased sharply, probably because only the edges of six of the sample pupils were located at this distance from the center of the pupil. c, Comparison of Zernike coefficient estimates gathered from subject S3 on three separate days spanning a month. Each curve is the average estimate for that day.

Fig. 5
Fig. 5

Wave-front height contours for subject S1. Contours are calculated for a 7.32-mm pupil and are spaced at 1-µm intervals. Defocus was excluded from the calculation of the wave front. Top row, plots from three sequential runs collected in a single day. Bottom row, three sequential runs from a different day.

Fig. 6
Fig. 6

Wave-front maps for all six subjects. Contours are plotted at 1-µm intervals and do not include defocus but do include all other Zernike terms up to 35. The variation among individuals in the optical quality of the eye is evident. Subject S4, for instance, has only approximately 1 µm of aberrations across his entire pupil.

Fig. 7
Fig. 7

Comparison of wave-front maps for subjects S1 and S3 under different experimental conditions. Leftmost column, data collected with free accommodation to a target at the subject’s far point. Middle column, data collected from the same subjects but after administration of 0.5% tropicamide to dilate the pupil. These data were collected under identical conditions to those that produced the data in the leftmost column, including bite bar and target positions. Rightmost column, data collected when the refraction control is used to generate a 4-D accommodative stimulus.

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