Introducing a new model for studying retinal detachement/replacement: a light microscopy and electrophysiological study

ABSTRACT

The toad's [Bufo maranus] retinal pigment epithelium [RPE] has been used in many studies as a model for understanding its role and interaction with the neural retina. In the current study, the toad's retina has been used to establish a new in vitro model of experimental retinal detachment [RD] and replacement. The toad was chosen according to a previous study of our research group showed that the toad RPE is similar to the mammalian RPE. In this report, light microscopy was used to characterize the morphologic changes that occur in the RPE and neural retina following RD/replacement and to correlate these findings with recovery of electrophysiological function. The neural retina was completely detached from the RPE in vitro and then replaced. At various times after replacement, neural retina-RPE tissues were processed for light microscopy. At 30 min. after replacement, the subretinal space was greatly expanded, and the apical processes that normally ensheath the outer segments of neural retina were short and no longer contacted the outer segments of neural retina. The RPE was swollen, contained many vacuoles and the apical surface was rounded. By 2 hours after replacement, the subretinal space was significantly resorbed and contained many shredded neural retina outer segments; RPE cells were still, although less, swollen. During the next 5-10 hours, shredded neural retina outer segment in the subretinal space appeared decreased. RPE cells regained their normal size and interdigitation of apical processes and neural retina outer segment were observed. In conclusion, these results demonstrate the re-establishment of morphological interactions between the RPE and neural retina within hours following RD/replacement. Morphological recovery coincides with recovery of electrophysiological parameters. This is a good model to investigate the retinal pigment epithelium [RPE] and neural retina mechanisms involved in retinal adhesion and recovery from retinal detachment and is easier to be applied than previously described models