Pigmented layer of optical retina

The pigmented layer of optical retina (a.k.a. the retinal pigment epithelium or RPE), is the outermost layer of the optic part of the retina and lies directly adjacent to the choroid. It consists of a single layer of hexagonal, cuboidal cells that are densely packed with melanin granules, giving it a dark appearance. This pigmentation plays a crucial role in absorbing excess light, thereby preventing internal reflection within the eye and enhancing visual acuity.

Structurally, the pigmented layer of optical retina is firmly attached to the underlying choroid but only loosely adherent to the overlying neural retina, a relationship that is clinically significant in conditions such as retinal detachment. The apical surfaces of RPE cells possess numerous microvilli that interdigitate with the outer segments of photoreceptors (rods and cones), forming a close functional relationship with the photoreceptors.

Clinically, dysfunction or degeneration of the RPE is implicated in several important retinal diseases, including age related macular degeneration (AMD) and retinitis pigmentosa, both of which can lead to progressive vision loss.