Macular Degeneration is a disease with both genetic and environmental risk factors and is without cure. Many of these risk factors appear to be related directly or indirectly to oxidative damage in the retina/RPE. Low levels of lutein and zeaxanthin in the diet and in the blood serum have been shown to be associated with an increased risk of AMD. These are the carotenoids which comprise the macular protective pigment, which itself is associated with the prevalence of AMD. Studies using autopsy eyes, as well as studies of AMD subjects, point to an increased risk of AMD when a person's macular protective pigment level is low. There are reasons why these associations might be expected. macular protective pigment in high concentrations in photoreceptor axons screens vulnerable tissues in the macular region from the damaging effects of actinic blue light. Secondly, lutein and zeaxanthin are potent antioxidants, and this may be their primary function in photoreceptor outer segments.
How can a person determine his or her macular protective pigment status? A new instrument, the Macuscope, has recently become commercially available. The Macuscope is a "heterochromatic flicker photometer," based on a design that has evolved and proven its worth as a powerful and well validated research instrument. Through a brief test, it provides the optical density (absorbance) of the patient's macular protective pigment, a quantity that is proportional to the pigment concentration itself. Those whose dietary intake of green, leafy vegetables is poor or non-existent invariably score low, whereas those with a high intake, including vegetarians, are typically high.
Assuming that it is determined that a person's macular protective pigment level is low, a second question is whether anything can be done about it. Lutein and zeaxanthin in the retina are of dietary origin, and supplements consisting of these carotenoids, particularly lutein, are readily available. Numerous studies have been conducted in which subjects were given supplements and their macular protective pigment levels monitored using the Macuscope principle. In most cases, the subjects responded, with macular protective pigment increases of up to 40% in as little as 6 months of supplementation. The instrument, in its commercial form, is designed to make the test as simple as possible. The patient observes a small, flickering visual stimulus, and is asked to respond "more" or "less" to the degree of flicker as adjustments are made by the operator. The task is similar to that posed by the optometrist who fine-tunes the lens prescription by asking the patient "Which is better, this or this?" AMD is a devastating condition, both socially and economically. Lutein supplementation, monitored by an instrument such as the Macuscope, could have a significant impact on the prevalence of this disease.