Date of Award

Spring 1994

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

First Advisor

Kenneth Fuld

Abstract

Differences in the optical density of macular pigment between ten pairs of identical twins were examined. Foveal and parafoveal sensitivities to lights of 460 and 530 nm were measured by heterochromatic flicker photometry in five separate sessions for the right eye of each twin. These two wavelengths represent the maximum and minimum absorbance for macular pigment. Taking the difference in log sensitivity to the 460 nm light for the fovea and parafovea, after normalizing with respect to 530 nm, yields a measurement of the optical density of macular pigment. Statistically significant differences in macular pigment density were found for five of the ten twin pairs. These differences were then related to differences in the carotenoid content of the subject's serum (as measured by reverse-phase high-performance liquid chromatography) and differences in the dietary intake of carotenoids (as assessed by a dietary questionnaire). While only a small relationship was found between differences in macular pigment density and the serum and dietary carotenoids that compose macular pigment (lutein and zeaxanthin), a systematic relationship was found between macular pigment density and a number of other diet variables that influence carotenoid metabolism. Taken together, the data support earlier research on the importance of diet in determining macular pigment levels. However, it is likely that this relationship is complex and that the eventual deposition of macular pigment within the eye is influenced by a number of other diet variables rather than simply carotenoid intake.

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