Photoprotection role of melanin in the human retinal pigment epithelium. Imaging techniques for retinal melanin.

The human eye is made up of multiple layers of pigmented tissues that have in componence melanin. In the eye, one can separate melanosomes from various embryonic origins. The pigment-producing cells in the stroma of the iris, ciliary body and the choroid (uveal melanocytes) are neural crest derivatives. On the other hand, ciliary, iris and retinal pigment epithelial cells are developed from the neural ectoderm. One universally accepted role of melanin is to react as neutral-density filter in scattering light. Melanin acts as a free radical stabilizer and has the ability to absorb near-infrared, visible light and UV radiation. This paper reviews the current knowledge on ocular melanin, including ocular melanogenesis, roles of melanin in retinal metabolic processes and some imaging techniques that identify melanin in the retina.