Morphologic preservation and variability of human donor retina

Purpose. To facilitate studies of human retina and utilization of human ret inal tissue for treatment of retinal diseases, we studied morphologic prese rvation in postmortem human retina. Methods. Morphology of retinas from thirty-one human eyes was examined usin g light and electron microscopy. The inner and outer retina, rod and cone p hotoreceptor cells, and central and peripheral retina were compared with re gard to morphologic preservation. Possible factors affecting survival were analyzed. Results. The earliest postmortem change was vacuolation of the nerve fiber layer within a few hours postmortem, followed by vacuolation and cytoplasmi c swelling of the inner retina. As compared with the inner retina, outer re tinal structure was better preserved, i.e., the photoreceptor cells maintai ned better morphology. Rod cell morphology was better preserved than cone c ell morphology, with good preservation of the rod outer segment disc membra nes and the inner segment mitochondrial membranes. Thus, well-preserved rod photoreceptor cells were evident in specimens at least 48-hours postmortem . Peripheral retina was better preserved than the central retina including the fovea and perifovea. Factors affecting anatomical integrity included th e total time postmortem and, more importantly, the time between death and e nucleation. Other factors, including age and sex, did not appear to affect morphological preservation in the present study. Conclusions. Human retina postmortem remained morphologically intact for a relatively long period of time, with differential preservation among differ ent geographic areas and cell types. This morphologic evidence is consisten t with previous findings of functional preservation (e.g., photoresponses) in such tissue. This study may shed some light on understanding of human re tina and its utilization for retinal transplantation.