You Gotta Eat the Lettuce: An Examination of the Effects of Lutein and Zeaxanthin on Contrast Sensitivity

Lutein and zeaxanthin are two important carotenoid vitamins related to ocular health and human visual processing. These vitamins can be ingested through supplementation and in regular diet. They concentrate in the central retina where they form a filter of macular pigment and protect the eye from high energy blue and yellow light. We examined participants who had a natural diet of high vs low lutein and zeaxanthin intake on tests of contrast sensitivity and glare disability. We also examined participant performance while wearing blue light blocking glasses in order to determine whether these glasses serve a similar protective function as macular pigment in benefiting participants on contrast sensitivity and glare disability tasks. Most of our data did not show statistically significant differences between the high and low lutein and zeaxanthin groups. An unexpected result that the blue blocker glasses hindered the ability of low lutein participants on their glare disability test was observed. We hypothesize that this is due to light scatter produced by the by glasses resulting in an impoverish retinal image reaching the primary visual cortex. Further research is required to examine this new finding.