Iris pigment epithelium
Despite their very different functions and histological appearances, these regions have a common origin from the two layers of the embryological optic cup.The melanosomes of the IPE are distinctive, being larger, blacker and rounder than those in the ciliary epithelium or RPE.[1] The IPE is affected by glaucoma, diabetes, and iris inflammations and atrophies of various kinds, generally responding by showing patchy thinning and depigmentation.In albinism, it is fully or partially nonpigmented and translucent, which contributes to the photophobia of that condition.However, diseases specific to the IPE itself are almost non-existent, and it seems to be a highly differentiated, stable cell type that almost never gives rise to malignancies, unlike the melanocytes of the iris stroma.