Detached outer retina surface tension is dictated by pericellular interphotoreceptor matrix

Abstract

Purpose : Little is known about the nature of adhesive interactions between the retina and retinal-pigmented epithelium (RPE). Such interactions may play an important role in maintaining normal retinal attachment, and the pathophysiology of detachment. Here, we ask what structures contribute to the critical surface tension of the outer retinal surface.

Methods : We used a material sciences approach to examine the physical and biochemical characteristics of the outer retinal surface of detached bovine retina. Contact angle goniometry determined the critical surface tension of the outer retinal surface, isolated insoluble interphotoreceptor matrix (IPM) and purified interphotoreceptor retinoid binding protein (IRBP). Mid-infrared attenuated total reflectance (MIR-ATR) spectroscopy was used to characterize the molecular composition of the retinal surface. This data was correlated with light microscopy, immunohistochemistry and electronmicroscopy study of the detached retinal surface. MIR-ATR depth penetration was established through ellipsometric measurement of barium-sterate films. This data was correlated to MIR-ATR spectra of docosahexaenoic acid, hyaluronan, chondroitin-6-sulfate and IRBP.

Results : We found that the retinal surface tension is 24 mN/m similar to isolated insoluble IPM and lower than IRBP. Barium-sterate calibration studies established that the MIR-ATA spectroscopy penetration depth to be only 0.3 µm. Correlation with electronmicroscopy and immunohistochemical studies indicate that a layer of IPM coating the outer retinal surface is responsible for these properties.

Conclusions : The surface tension of detached bovine retina is dictated not by the outer segments, but by a thin film of IPM coating its outer surface. These observations may help us to understand the molecular pathophysiology of retina adhesion and detachment.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.