Retinal pigment epithelial cells (RPE) constitute a simple layer of cuboidal cells that are
strategically situated behind the photoreceptor (PR) cells. The inconspicuousness of this …

As succinctly summarized by Wolf, 1 lack of vitamin A (all-trans-retinol) was recognized by
ancient Egyptians as causing a visual deficiency involving the retina and cornea that could …

Leber congenital amaurosis (LCA) is the most severe retinal dystrophy causing blindness or
severe visual impairment before the age of 1 year. Linkage analysis, homozygosity mapping …

Following exposure of our eye to very intense illumination, we experience a greatly elevated
visual threshold, that takes tens of minutes to return completely to normal. The slowness of …

Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is
essential for several physiological processes. Either hyper-or hypovitaminosis can be …

Absorption of a photon by an opsin pigment causes isomerization of the chromophore from
11-cis-retinaldehyde to all-trans-retinaldehyde. Regeneration of visual chromophore …

Lecithin-retinol acyltransferase (LRAT), an enzyme present mainly in the retinal pigmented
epithelial cells and liver, converts all-trans-retinol into all-trans-retinyl esters. In the retinal …

Recessive Stargardt disease (STGD1) is an inherited blinding disorder caused by mutations
in the Abca4 gene. ABCA4 is a flippase in photoreceptor outer segments (OS) that …

The chromophore of all known visual pigments consists of 11-cis-retinal (derived from either
vitamin A1 or A2) or a hydroxylated derivative, bound to a protein (opsin) via a Schiff base …

Vitamin A is an essential nutrient required throughout life. Through its various metabolites,
vitamin A sustains fetal development, immunity, vision, and the maintenance, regulation, and …