The impact of aberrations in a 3D retinal model eye

Aberrations of the eye degrade the ocular point-spread function thereby reducing the attainable visual acuity. It is common practice to distinguish between lower and higher-order monochromatic aberrations of the eye when differentiating between what can be corrected with sphere and cylinder, and what cannot. Nevertheless, at the retina it matters more whether light is incident along or obliquely onto the elongated photoreceptors. In this contribution, I discuss the impact of different Zernike aberration terms not at the pupil, but at the retina. Even-ordered monochromatic Zernike aberrations have an associated wavefront slope at the retina whereas odd-ordered Zernike aberration modes have no wavefront tilt across the point-spread function. In other words, even and odd-ordered Zernike modes are affected differently by the Stiles-Crawford effect of the first kind that relates to obliqueness of light at the retina. Understanding this is essential to decode how vision is triggered in normal viewing conditions as well as when probing vision and photoreceptors with psychophysical methods in the analysis of vision or for ophthalmic design. Finally, a uniaxial pupil flicker system is used to directly measure the integrated Stiles-Crawford effect in the author’s eye in order to assess apodization of oblique light in normal vision.