Ocular disorders secondary to systemic disease and the potential role of carnitines.

L-carnitine has a wide-ranging role in several physiological processes, but perhaps most significantly in long-chain fatty acid oxidation in the mitochondrial matrix. Osmolytic (or osmoprotective) properties have also been suggested for the compound. Importantly, the ability of L-carnitine to improve insulin sensitivity in insulin-resistant diabetic patients may, together with the agent's antioxidant and antiapoptotic activity, provide some degree of protection against the progression of diabetic retinopathy. L-carnitine may also protect against the deleterious effects of ocular ischaemic syndrome, and, indeed, acetyl-L-carnitine has been shown to significantly improve retinal damage and visual acuity in patients with monolateral or bilateral retinal artery occlusion. The antioxidant, antiapoptotic and osmolytic properties of L-carnitine also suggest that this agent may have valuable clinical utility in neurotrophic keratopathy and bullous keratopathy. Thus, further detailed investigation of the important clinical potential of L-carnitine in various ocular conditions (e.g. diabetic retinopathy, ocular ischaemic syndrome, neurotrophic keratopathy and bullous keratopathy) that occur secondary to systemic diseases is now clearly warranted.