Abstract

A computer model that incorporates the monochromatic aberrations of the eye is used to determine the optimal pupil size for axial and lateral resolution as it applies to retinal imaging instruments such as the confocal scanning laser ophthalmoscope. The optimal pupil size for axial resolution, based on the aberrations of 15 subjects, is 4.30 mm±1.19 mm standard deviation (sd), which is larger than that for lateral resolution [2.46 mm±0.66 mm (sd)]. When small confocal pinholes are used, the maximum detected light is obtained with a pupil size of 4.90 mm±1.04 mm sd. It is recommended to use larger pupil sizes in imaging applications where axial resolution is desired.

© 2003 Optical Society of America

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References

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  8. A. Roorda, “Double pass reflections in the human eye,” Ph.D. thesis (University of Waterloo, Waterloo, Ontario, Canada, 1996).
  9. T. Wilson, “The role of the pinhole in confocal imaging systems,” in The Handbook of Biological Confocal Microscopy, J. B. Pawley, ed. (Plenum, New York, 1990), pp. 99–113.
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    [CrossRef] [PubMed]

1997

1989

1987

1986

G. J. van Blokland, “Directionality and alignment of the foveal receptors, assessed with light scattered from the human fundus in vivo,” Vision Res. 26, 495–500 (1986).
[CrossRef] [PubMed]

1984

1977

1966

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

1965

F. W. Campbell, D. G. Green, “Optical and retinal factors affecting visual resolution,” J. Physiol. 181, 576–593 (1965).
[PubMed]

Bennett, A. G.

A. G. Bennett, R. B. Rabbetts, Clinical Visual Optics, 2 (Butterworth, London, 1989).

Bille, J. F.

Campbell, F. W.

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

F. W. Campbell, D. G. Green, “Optical and retinal factors affecting visual resolution,” J. Physiol. 181, 576–593 (1965).
[PubMed]

Charman, W. N.

Delori, F. C.

Dreher, A. W.

Green, D. G.

F. W. Campbell, D. G. Green, “Optical and retinal factors affecting visual resolution,” J. Physiol. 181, 576–593 (1965).
[PubMed]

Gubisch, R. W.

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

Howland, B.

Howland, H. C.

Hughes, G. W.

Liang, J.

Rabbetts, R. B.

A. G. Bennett, R. B. Rabbetts, Clinical Visual Optics, 2 (Butterworth, London, 1989).

Roorda, A.

A. Roorda, “Double pass reflections in the human eye,” Ph.D. thesis (University of Waterloo, Waterloo, Ontario, Canada, 1996).

Sheppard, C. J. R.

T. Wilson, C. J. R. Sheppard, Theory and Practice of Scanning Optical Microscopy (Academic, London, 1984).

van Blokland, G. J.

G. J. van Blokland, “Directionality and alignment of the foveal receptors, assessed with light scattered from the human fundus in vivo,” Vision Res. 26, 495–500 (1986).
[CrossRef] [PubMed]

Walsh, G.

Webb, R. H.

Weinreb, R. N.

Williams, D. R.

Wilson, T.

T. Wilson, “The role of the pinhole in confocal imaging systems,” in The Handbook of Biological Confocal Microscopy, J. B. Pawley, ed. (Plenum, New York, 1990), pp. 99–113.

T. Wilson, C. J. R. Sheppard, Theory and Practice of Scanning Optical Microscopy (Academic, London, 1984).

Appl. Opt.

J. Opt. Soc. Am.

J. Opt. Soc. Am. A

J. Physiol.

F. W. Campbell, D. G. Green, “Optical and retinal factors affecting visual resolution,” J. Physiol. 181, 576–593 (1965).
[PubMed]

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

Vision Res.

G. J. van Blokland, “Directionality and alignment of the foveal receptors, assessed with light scattered from the human fundus in vivo,” Vision Res. 26, 495–500 (1986).
[CrossRef] [PubMed]

Other

A. G. Bennett, R. B. Rabbetts, Clinical Visual Optics, 2 (Butterworth, London, 1989).

T. Wilson, C. J. R. Sheppard, Theory and Practice of Scanning Optical Microscopy (Academic, London, 1984).

A. Roorda, “Double pass reflections in the human eye,” Ph.D. thesis (University of Waterloo, Waterloo, Ontario, Canada, 1996).

T. Wilson, “The role of the pinhole in confocal imaging systems,” in The Handbook of Biological Confocal Microscopy, J. B. Pawley, ed. (Plenum, New York, 1990), pp. 99–113.

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Figures (8)

Fig. 1
Fig. 1

Procedure for calculating axial resolution. First the 3D PSF is calculated as a sequence of 40 PSF images, with intensities relative to the diffraction-limited eye. Each value on each slice of the 3D PSF is squared, and then each slice is integrated and plotted against its axial position. The FWHM of the resulting function is computed to get the axial resolution.

Fig. 2
Fig. 2

3D PSF with changing pupil size. The squared PSFs are shown here. In the diffraction-limited eye (upper series of PSFs), the squared 3D PSF becomes more compact, both laterally and axially. For a typical eye (lower series of PSFs), the squared 3D PSF looks similar to that in the diffraction-limited case for small pupils and starts to reduce in size with an increase in pupil size. After a certain point, aberrations begin to spread the PSF again.

Fig. 3
Fig. 3

(a) Integrated through-focus intensity of the 3D PSF as a function of axial location plotted for a diffraction-limited eye. Each curve segment shows one through-focus intensity plot over a 2-mm axial depth of the 3D PSF (the scale for each curve segment is not shown). The series of segments represent the individual plots for each pupil size. As expected, the detected intensity increases as the pupil size increases, and the width of the integrated intensity plots decreases as the pupil size increases. (b) Through-focus Strehl ratio as a function of axial location for a diffraction-limited eye for a range of pupil sizes. The Strehl ratio is always equal to 1 at the best focal plane.

Fig. 4
Fig. 4

(a) Integrated intensity of the 3D PSF as a function of axial location plotted for a typical eye (subject AV). The detected intensity increases to a point but then decreases as the pupil size increases. Similarly, the width of the integrated intensity plots narrows with increasing pupil size to a point (∼3 mm) but then increases again as pupil size increases. Plots of the FWHM of these curves are shown in Fig. 5. (b) Through-focus Strehl ratio as a function of axial location for a diffraction-limited eye. The Strehl ratio is close to 1 for small pupils but decreases to ∼0.05 for a 6-mm pupil.

Fig. 5
Fig. 5

Plots of axial resolution versus pupil diameter. All subjects are shown here including the diffraction-limited eye, labeled D-L. For all cases but one (subject BW), the axial resolution reached a minimum for a pupil size between 2 and 6 mm.

Fig. 6
Fig. 6

Plots of lateral resolution (50% encircled energy) versus pupil diameter. All subjects are shown here including the diffraction-limited eye, labeled D-L. For all cases, the lateral resolution reaches a minimum for a pupil size between 2 and 6 mm.

Fig. 7
Fig. 7

Comparison of best pupil for axial resolution versus best pupil for lateral resolution. The correlation between the two numbers is very low, indicating that if the pupil size for best lateral resolution is known, it is not possible to predict the best pupil for axial resolution.

Fig. 8
Fig. 8

Comparison of best axial resolution versus best lateral resolution. This plot indicates that improving the lateral resolution will also increase the axial resolution.

Tables (1)

Tables Icon

Table 1 Summary of Optimal Pupil Sizes for Axial Resolution, Lateral Resolution, and Maximum Detected Intensity

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