From Wikipedia, the free encyclopedia. The pigmented layer of retina or retinal pigment epithelium (RPE) is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells.Contents.n the eyes of albinos, the cells of this layer contain no pigment. Dysfunction of the RPE is found in Age-Related Macular Degeneration and Retinitis Pigmentosa. RPE are also involved in Diabetic retinopathy.