Physical and Optical Changes in Excised Retinal Tissue: Resolution of Retinal Receptors as a Fiber Optic Bundle

¹ Department of Ophthalmology, Washington University Medical School and The Oscar Johnson Institute St. Louis, Mo.

Excised retinal tissue exhibits degenerative changes. Measurable (and, in time, substantial) variations in physical and optical characteristics are recorded virtually instantaneously in some preparations, and after a brief delay in others. (Instantaneously, as used here, means as fast as toe can place the tissue into position for observation.) In this study, we are most concerned with the nature of the changes which occur, and the development of techniques for evaluating them. We note swelling in three dimensions, decreased light transmission, increased scattered light which changes its distribution in time, and decreased resolution capability of the retina acting as a fiber optic bundle. The latter loss is only slightly accounted for by receptor swelling. We have used three species (albino rats, albino rabbits, and squirrel monkeys). We have tried different media, e.g., aqueous, TC 199, phosphate buffer, and normal saline. We have left the choroid attached to the retina in some preparations. The simple techniques described herein should allow investigators to evaluate partially the status of retinal organ cultures as well as excised retinal blocks. These indicators should be correlated with electrophysiological data. We hope to couple these techniques in an in situ perfused preparation which we are developing. This model should be valuable in studies of experimental pathology of the retina as well as studies of receptor wave-guide properties, photopigments, retinal resolution properties, etc. Further proof that the retina acts as a fiber optic bundle has been added. It has been shown that the resolution of the retina as a fiber optic bundle approaches the theoretical maximum. Disturbed receptor orientation can cause loss in resolution capability