Figure 6
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Figure 6 |
Vitamin A deficiency causes several retinal problems. Vitamin A is a fat-soluble vitamin that is converted to retinal in mucosol cells of the small intestine. It is stored in the liver as retinyl palmitate and synthesized from isoprenoid compounds (Rhodopsin Pathway in the Eye). The retinal form is converted to 11-cis retinal to bind to the protein rhodopsin via a Schiff base on a lysine . From the B-carotene, zeaxanthin is formed and from the lycopene precursor of B-carotene, lutein is formed. Lutein and zeaxanthin are essential components to rod and cone cells (respectively). These components are essential to the health of the retina overall. The ability refined rods to recognize and discriminate between colors is dependent upon the presence and concentration of the lutein and zeaxanthin (Ong).