The Optics and Physiology of the Eye in Relation to Laser Injury

Abstract

The eye has several surprising optical properties: although it is an extremely wide angle (almost 180 degrees) system, no vignetting is noticed. This is due to the peripheral image being closer to the principal point, thus producing a smaller and brighter image to compensate for the reduced pupil area. Also, The central image does not have a small image as the image is focussed behind the retina, hyperopia of normal eye. The cone shape tends to defocus any light not absorbed by the visual pigment outside of the fovea. The dark adaptation of the rods and cones is more similar than is given in standard references on the subject. The significance of these properties is discussed in relation to retinal injury levels and flash blindness from laser exposures.The eye has several surprising optical properties: although it is an extremely wide angle (almost 180 degrees) system, no vignetting is noticed. This is due to the peripheral image being closer to the principal point, thus producing a smaller and brighter image to compensate for the reduced pupil area. Also, The central image does not have a small image as the image is focussed behind the retina, hyperopia of normal eye. The cone shape tends to defocus any light not absorbed by the visual pigment outside of the fovea. The dark adaptation of the rods and cones is more similar than is given in standard references on the subject. The significance of these properties is discussed in relation to retinal injury levels and flash blindness from laser exposures.