Pigmentepithel

Pigmentepithel, commonly referred to as the retinal pigment epithelium (RPE), is a single layer of pigmented cells in the retina. It lies between the neural retina and the choroid, with the apical surface in contact with photoreceptor outer segments and the basal surface resting on Bruch’s membrane. The cells contain melanin pigment and are joined by tight junctions, contributing to the outer blood-retina barrier.

The RPE performs a range of essential functions for visual health. It absorbs excess light to reduce scattering and phototoxic damage, helping to sharpen vision. It phagocytoses shed photoreceptor outer segments, a daily renewal process critical for photoreceptor longevity. The RPE is involved in the visual cycle, regenerating 11-cis-retinal from all-trans-retinal through enzymes such as RPE65 and LRAT, thereby supplying photoreceptors with the chromophore needed for vision. It also transports ions, water, and nutrients between the retina and choroid, maintains the subretinal environment, and secretes growth factors and anti-angiogenic signals. Immune regulation and waste management are additional aspects of its role.

Developmentally, the RPE arises from the neural retina’s precursor tissues during embryogenesis and differentiates into a specialized, metabolically active layer. Clinically, dysfunction or degeneration of the pigmentepithel is central to several retinal diseases. Age-related macular degeneration (AMD) involves RPE atrophy and drusen formation, sometimes with choroidal neovascularization. Inherited conditions such as Leber congenital amaurosis (LCA) and some retinitis pigmentosa forms involve RPE-related genes, including those affecting the visual cycle. Treatments include anti-VEGF therapy for AMD, gene therapies targeting RPE pathways (notably RPE65-related conditions), and emerging cell-based or transplant approaches to restore RPE function.