Abstract

We measured the improvement in retinal image quality provided by correcting the temporal variation in the eye’s wave aberration with a closed-loop adaptive optics system. This system samples the eye’s wave aberration at rates up to 30 Hz. Correction of the eye’s aberrations can be completed in 0.25–0.5 seconds, resulting in residual rms wave-front errors as low as 0.1 microns for 6.8 mm pupils. Real-time wave-front measurements were used to determine how effectively the spatial and temporal components of the eye’s wave aberration were corrected. The system provides dynamic correction of fluctuations in Zernike modes up to 5th order with temporal frequency components up to 0.8 Hz. Temporal performance is in good agreement with predictions based on theory. Correction of the temporal variation in the eye’s wave aberration increases the Strehl ratio of the point spread function nearly 3 times, and increases the contrast of images of cone photoreceptors by 33% compared with images taken with only static correction of the eye’s higher order aberrations.

© Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |

  1. M.S. Smirnov, "Measurement of the wave aberration of the human eye," Biophysics 6, 776-794 (1961).
  2. J. Liang, D. R. Williams, and D. T. Miller, "Supernormal vision and high resolution retinal imaging through adaptive optics," J. Opt. Soc. Am. A. 14, 2884-2892 (1997).
    [CrossRef]
  3. F. Vargas-Martin, P. Prieto, and P.Artal, "Correction of the aberrations in the human eye with liquid crystal spatial light modulators: limits to the performance," J. Opt. Soc. Am. A. 15, 2552-2562 (1998).
    [CrossRef]
  4. R. Navarro, E. Moreno-Barriuso, S. Bara, and T. Mancebo, "Phase plates for wave-aberration compensation in the human eye," Opt. Lett. 25, 236-238 (2000).
    [CrossRef]
  5. H. Hofer, P. Artal, B. Singer, J. L. Arag�n, and D. R. Williams, "Dynamics of the eye's wave aberration," J. Opt. Soc. Am. A. 18, 497-506 (2001).
    [CrossRef]
  6. E. J. Fernandez, I. Iglesias, P. Artal, "Closed-loop adaptive optics in the human eye," Opt. Lett. 26, 746-748 (2001).
    [CrossRef]
  7. American National Standard for the Safe Use of Lasers ANSI Z136.1. (Laser Institute of America, Orlando, FL, 1993).
  8. W. Jiang, and H. Li, "Hartmann-Shack wavefront sensing and control algorithm," SPIE 1271, Adaptive Optics and Optical Structures, 82-93 (1990)
    [CrossRef]
  9. S. Marcos, S. A. Burns, E. Moreno-Barriuso, and R. Navarro, "A new approach to the study of ocular chromatic aberrations," Vision Res. 39, 4309-4323 (1999).
    [CrossRef]
  10. G. Y. Yoon and D. R. Williams, "Visual performance after correcting the monochromatic and chromatic aberrations of the eye," J. Opt. Soc. Am. A., submitted (2001).
  11. W.N. Charman and G. Heron, "Fluctuations in accommodation: a review," Ophthal. Physiol. Opt. 8, 153-163 (1988).
    [CrossRef]
  12. A. Roorda and D.R. Williams, "The arrangement of the three cone classes in the living human eye," Nature 397, 520-522 (1999).
    [CrossRef] [PubMed]

Other

M.S. Smirnov, "Measurement of the wave aberration of the human eye," Biophysics 6, 776-794 (1961).

J. Liang, D. R. Williams, and D. T. Miller, "Supernormal vision and high resolution retinal imaging through adaptive optics," J. Opt. Soc. Am. A. 14, 2884-2892 (1997).
[CrossRef]

F. Vargas-Martin, P. Prieto, and P.Artal, "Correction of the aberrations in the human eye with liquid crystal spatial light modulators: limits to the performance," J. Opt. Soc. Am. A. 15, 2552-2562 (1998).
[CrossRef]

R. Navarro, E. Moreno-Barriuso, S. Bara, and T. Mancebo, "Phase plates for wave-aberration compensation in the human eye," Opt. Lett. 25, 236-238 (2000).
[CrossRef]

H. Hofer, P. Artal, B. Singer, J. L. Arag�n, and D. R. Williams, "Dynamics of the eye's wave aberration," J. Opt. Soc. Am. A. 18, 497-506 (2001).
[CrossRef]

E. J. Fernandez, I. Iglesias, P. Artal, "Closed-loop adaptive optics in the human eye," Opt. Lett. 26, 746-748 (2001).
[CrossRef]

American National Standard for the Safe Use of Lasers ANSI Z136.1. (Laser Institute of America, Orlando, FL, 1993).

W. Jiang, and H. Li, "Hartmann-Shack wavefront sensing and control algorithm," SPIE 1271, Adaptive Optics and Optical Structures, 82-93 (1990)
[CrossRef]

S. Marcos, S. A. Burns, E. Moreno-Barriuso, and R. Navarro, "A new approach to the study of ocular chromatic aberrations," Vision Res. 39, 4309-4323 (1999).
[CrossRef]

G. Y. Yoon and D. R. Williams, "Visual performance after correcting the monochromatic and chromatic aberrations of the eye," J. Opt. Soc. Am. A., submitted (2001).

W.N. Charman and G. Heron, "Fluctuations in accommodation: a review," Ophthal. Physiol. Opt. 8, 153-163 (1988).
[CrossRef]

A. Roorda and D.R. Williams, "The arrangement of the three cone classes in the living human eye," Nature 397, 520-522 (1999).
[CrossRef] [PubMed]

Supplementary Material (2)

» Media 1: MOV (633 KB)     
» Media 2: MOV (64 KB)     

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (12)

Fig. 1.
Fig. 1.

Schematic of the AO system setup.

Fig. 2.
Fig. 2.

Movie of the measured wave aberration, for one subject, during AO correction at 21 Hz. Contour lines represent one wavelength (0.55 microns) of aberration. Pupil size is 6.8 mm. (636K 256×256)

Fig. 3.
Fig. 3.

Point spread function calculated from the measured wave aberration at a wavelength of 0.55 microns for a 6.0 mm pupil, for the same subject, during AO correction at 21 Hz. (68K 256×256)

Fig. 4.
Fig. 4.

Single retinal images for one subject b) with and a) without AO. The location is 1.25 degree eccentricity on the temporal retina. These images were taken on the same day under identical conditions except that the DM was perfectly flat for the image taken without AO and warped in a compensated position for the image taken with AO. The subject’s refractive error was corrected to optimize the quality of the retinal image taken without AO.

Fig. 5.
Fig. 5.

Wave-front disturbance power spectra with dynamic and static AO averaged for 6 subjects, 6 mm pupil size.

Fig. 6.
Fig. 6.

Disturbance power rejection curve averaged for 6 subjects and the theoretical prediction. Error bars are the standard deviation across subjects. The frequency where this curve crosses one represents the correction bandwidth of the system.

Fig. 7.
Fig. 7.

Reduction of the power in the fluctuations of various Zernike mode orders with dynamic AO correction. Average of 6 subjects, 6.8 mm pupil size. Error bars indicate the spread for the subjects. The average power reduction is statistically significant for Zernike modes up to and including 5th order.

Fig. 8.
Fig. 8.

Time-averaged Strehl ratio for 6 subjects computed from the measured wave aberration with no AO correction (correction of only defocus and astigmatism), static AO correction, and dynamic AO correction. Error bars are the standard deviation across subjects.

Fig. 9.
Fig. 9.

Examples of retinal images taken with dynamic (top row) and static (bottom row) AO correction. Location was 1.25 degrees retinal eccentricity. Each image is an average of approximately 20 individual images. All images are shown at the same scale.

Fig. 10.
Fig. 10.

Radially-averaged retinal image power spectra for one subject (AP), with dynamic (blue) and static (pink) correction of they eye’s aberrations. The peak at ~80 cycles/degree represents cone photoreceptors. At this frequency the power spectrum is approximately 3 X higher with dynamic then with only static correction of the eye’s aberrations.

Fig. 11.
Fig. 11.

The average improvement in the retinal image power spectrum when using dynamic instead of static AO. This is the ratio of the image power spectrum with dynamic AO to the spectrum with static AO, averaged across 5 subjects. The range of the subjects’ cone spatial frequencies is indicated on the plot.

Fig. 12.
Fig. 12.

The improvement in the contrast of cones in retinal images when using dynamic, instead of static, AO correction of the eye’s higher order aberrations. On average, cone contrast is 33% higher with dynamic AO than with static-only compensation.

Metrics