LRAT and Leber congenital amaurosis: During further drug optimization, 9-cis-retinyl acetate was identified as a useful nutritional supplement restoring vision in animal models of LCA. Oral administration of this retinoid to RPE65-/- or LRAT-/- mice led to the formation of isorhodopsin, detected by UV-vis spectroscopy in the protein sample purified from the rod OS membranes isolated from mouse eyes, and restored visual function, as determined by electroretinography (ERG).