The aging eye and the role of L-carnitine and its derivatives.

The majority of ocular pathologies originate from a functional deterioration of intraocular tissues. This age-related deterioration often occurs as a result of changes within the eye. There is growing interest in the role of natural or synthetic compounds, such as carnitine, for blocking, or slowing, the progress of this deterioration. L-carnitine and its derivatives are involved in numerous physiological reactions, including sugar aerobic metabolism, oxidative phosphorylation, fatty acid oxidation and osmosis. While carnitine levels in human ocular tissue are unknown, animal studies indicate that carnitine is differentially distributed within the eye with the highest concentrations reported in the iris, ciliary body and the choroid-retina. In patients with age-related macular degeneration (AMD), acetyl-L-carnitine improved four parameters of visual function, including visual field mean defect, visual acuity, foveal sensitivity and ocular fundus alterations. L-carnitine has also demonstrated antioxidant properties in animal models of oxidative damage. This article reviews the potential use of L-carnitine and its derivatives in age-related ocular pathologies, such as AMD, cataract, glaucoma and dry eye syndrome.