Protective role of carotenoids in the visual cycle

What is it about?

Increasing evidence suggests that the carotenoids zeaxanthin and lutein are beneficial to ocular health. These dietary pigments accumulate in the retina of many vertebrates, including humans. Carotenoids absorb short wavelength light and scavenge reactive oxygen species, both hallmarks of light-induced retinal damage. Therefore, over the counter supplements with zeaxanthin and lutein enjoy great popularity in the general population and constitute a multimillion dollar nutraceutical market. However, the lack of a suitable ophthalmic animal model with a 'carotenoid-rich' retina hindered detailed examination of the pigments' role in vision. By genetic manipulation, we established a mouse model with a 'carotenoid-rich' retina. This mouse model allowed testing the putative protective role of carotenoids against blue light-induced ocular damage in a small animal model with striking similarity to humans in anatomy and physiology. We observed that carotenoids shielded photoreceptors from blue light-induced photochemical modifications of the chromophore of visual pigments. Ocular carotenoids also ameliorated light-induced structural damage to the mouse retina. Our study establish a novel role of carotenoids in photoreceptor biology and indicate that carotenoids may protect the retina from the buildup of chromophore adducts which are found in several chronic eye disease states. A better understanding of the role of carotenoids in vision will aid in the development of nutritional intervention strategies to prevent chronic eye diseases.

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