Apodization by the Stiles-Crawford effect moderates the visual impact of retinal image defocus.

Previous optical modeling of the human eye with large pupils has predicted a larger impact of defocus on the human contrast sensitivity function and modulation transfer function than is observed experimentally. Theory predicts that aberrations and the Stiles-Crawford effect (SCE) should both lead to increased depth of focus, resulting in higher contrast sensitivities and veridical (not phase-reversed) perception over a larger range of spatial frequencies in defocused retinal images. Using a wave optics model, we examine these predictions quantitatively and compare them with psychophysical experiments that measure the effect of defocus on contrast sensitivity and perceived phase reversals. We find that SCE apodization has its biggest effect on defocused image quality when defocus and spherical aberration have the same sign. A model including typical amounts of spherical aberration and pupil apodization provides a dramatically improved prediction of the effects of defocus on contrast sensitivity with large pupils. The SCE can significantly improve defocused image quality and defocused vision, particularly for tasks that require veridical phase perception.

[1]  Jyrki Rovamo,et al.  Two simple psychophysical methods for determining the optical modulation transfer function of the human eye , 1994, Vision Research.

[2]  A. Bradley,et al.  The effect of pupil size on chromostereopsis and chromatic diplopia: Interaction between the Stiles-Crawford effect and chromatic aberrations , 1992, Vision Research.

[3]  T. Olsen.  On the Stiles‐Crawford effect and ocular imagery , 1993, Acta ophthalmologica.

[4]  F Thorn,et al.  Effects of Dioptric Blur on Snellen and Grating Acuity , 1990, Optometry and vision science : official publication of the American Academy of Optometry.

[5]  L J Bour.  MTF of the defocused optical system of the human eye for incoherent monochromatic light. , 1980, Journal of the Optical Society of America.

[6]  M. Mino,et al.  Improvement in the OTF of a Defocused Optical System Through the Use of Shaded Apertures. , 1971, Applied optics.

[7]  I Iglesias,et al.  Reconstruction of the point-spread function of the human eye from two double-pass retinal images by phase-retrieval algorithms. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[8]  P Artal,et al.  Incorporation of directional effects of the retina into computations of optical transfer functions of human eyes. , 1989, Journal of the Optical Society of America. A, Optics and image science.

[9]  W. Neil Charman,et al.  Comparison of the depths of focus with the naked eye and with three types of presbyopic contact lens correction , 1995 .

[10]  D. G. Green,et al.  Optical and retinal factors affecting visual resolution. , 1965, The Journal of physiology.

[11]  A. Bradley,et al.  Spherical Aberration of the Reduced Schematic Eye with Elliptical Refracting Surface , 1997, Optometry and vision science : official publication of the American Academy of Optometry.

[12]  D A Atchison,et al.  Influence of Stiles-Crawford effect apodization on spatial visual performance. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[13]  Junzhong Liang,et al.  Aberrations and retinal image quality of the normal human eye. , 1997, Journal of the Optical Society of America. A, Optics, image science, and vision.

[14]  J P Carroll.  Apodization model of the Stiles-Crawford effect. , 1980, Journal of the Optical Society of America.

[15]  F. W. Campbell,et al.  Effect of Focus on the Visual Response to a Sinusoidally Modulated Spatial Stimulus , 1965 .

[16]  F. Campbell,et al.  A method for measuring the depth of field of the human eye. , 1957, The Journal of physiology.

[17]  C. Krakau.  ON THE STILES‐CRAWFORD PHENOMENON AND RESOLUTION POWER , 1974, Acta ophthalmologica.

[18]  Harold Metcalf.  Stiles-Crawford Apodization , 1965 .

[19]  A. van Meeteren,et al.  Calculations on the Optical Modulation Transfer Function of the Human Eye for White Light , 1974 .

[20]  L. Thibos.  Calculation of the influence of lateral chromatic aberration on image quality across the visual field. , 1987, Journal of the Optical Society of America. A, Optics and image science.

[21]  B. Howland,et al.  A subjective method for the measurement of monochromatic aberrations of the eye. , 1977, Journal of the Optical Society of America.

[22]  I Iglesias,et al.  Estimates of the ocular wave aberration from pairs of double-pass retinal images. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[23]  A. Bradley,et al.  Theory and measurement of ocular chromatic aberration , 1990, Vision Research.

[24]  G E Legge,et al.  Tolerance to visual defocus. , 1987, Journal of the Optical Society of America. A, Optics and image science.

[25]  H. H. Hopkins.  The frequency response of a defocused optical system , 1955, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[26]  A. Bradley,et al.  Consequences of Monocular Diplopia for the Contrast Sensitivity Function , 1996, Vision Research.

[27]  W. N. Charman,et al.  Pupil Diameter and the Depth-of-field of the Human Eye as Measured by Laser Speckle , 1977 .

[28]  Wilson S. Geisler,et al.  The physical limits of grating visibility , 1987, Vision Research.

[29]  A Bradley,et al.  Effects of target distance and pupil size on letter contrast sensitivity with simultaneous vision bifocal contact lenses. , 1993, Optometry and vision science : official publication of the American Academy of Optometry.

[30]  R A Applegate,et al.  Parametric representation of Stiles-Crawford functions: normal variation of peak location and directionality. , 1993, Journal of the Optical Society of America. A, Optics and image science.

[31]  W N Charman,et al.  THE DEPTH‐OF‐FOCUS OF THE HUMAN EYE FOR SNELLEN LETTERS* , 1975, American journal of optometry and physiological optics.

[32]  D A Atchison,et al.  Predicting the effects of optical defocus on human contrast sensitivity. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[33]  W N Charman,et al.  Objective technique for the determination of monochromatic aberrations of the human eye. , 1984, Journal of the Optical Society of America. A, Optics and image science.

[34]  R A Applegate,et al.  Assessment of the accuracy of the crossed-cylinder aberroscope technique. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[35]  G Smith,et al.  OCULAR DEFOCUS, SPURIOUS RESOLUTION AND CONTRAST REVERSAL * , 1982, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[36]  R. Gubisch,et al.  Optical Performance of the Human Eye , 1967 .