The subretinal space is never bridged by tissue, and yet the neural retina remains firmly attached to the RPE throughout life. The RPE is crucial to maintaining retinal adhesion. Detachment of the photoreceptors from the RPE can lead to permanent morphologic and functional changes in the retina.
Numerous factors keep the retina in place. These include passive hydrostatic forces, interdigitation of outer segments and RPE microvilli, active transport of subretinal fluid, and the complex structure of the interphotoreceptor matrix and its binding properties (van der Waals forces). In pathologic conditions, retinal adhesion can diminish, and detachment of the retina occurs. Detachment does not occur simply because there is a hole in the retina or a leak in the RPE; there must be either positive traction pulling the neural retina or positive forces pushing fluid into the subretinal space that overwhelms the removal capacity of the RPE.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.