Retinal Image Formation: Review, Summary, and Discussion*

In this field the focus of attention has shifted from the optical image formed by the refracting surfaces of the eye to the optics of the retina. Retinal optics includes the Stiles–Crawford effects of the first and second kind, macular pigment, forward scatter, entoptic effects, and reflection by the pigment epithelium, choroid, and sclera. Three kinds of measurements of blur need to be compared: (1) blur of the optical image measured by cutting a hole through the coats of the eye to expose the vitreous, (2) blur of the image formed by light reflected from the retina, and (3) blur of the image transmitted by way of the optic nerve to the brain. The coarseness of the retinal mosaic and micronystagmus must be taken into account in dealing with resolving power. The motor mechanisms that have to be considered include those which control fixation and accommodation.