Retinal Pigment Epithelium

**Semantic type:** Tissue

**Definition:** A continuous, insulating monolayer of cuboidal/columnar epithelium which extends from the margins of the optic nerve head to the ora serrata where it is continuous with the pigment epithelium of the pars plana. This cell layer has many physical, optical, metabolic/biochemical and transport functions which play a critical role in the normal visual process, including acting as a selective filter to determine what nutrients reach the retina from the choroid.

**Synonyms:** - RETINAL PIGMENTED EPITHELIAL LAYER - RPE