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Factors affecting macular pigment optical density in a healthy cohort using a new optical instrument


Purpose : The macular pigment is a yellowish pigment of nutritional origin, lying primarily at the macula. It is believed to play a protective role, shielding foveal photoreceptors from blue-light associated photochemical damage and oxidation from free-radicals. The purpose of this study was to collect macular pigment optical density (MPOD) values, measured with a new optical instrument in a healthy population.

Methods : The instrument uses two sources, a green and a blue, flickering at different frequencies and focusing a central disk of 3.5 degrees diameter and a concentric peripheral annulus of 1 degree on the ocular fundus. The reflected light from the fundus is collected by a high-speed, high sensitivity photodetector and the signal is then processed in the frequency domain. The value for the macular pigment optical density is subsequently computed from the processed signal and the appropriate mathematical equation based on a fundus light extinction model. The duration of the measurement is kept below 0.2 sec and it is done at a natural pupil. Our cohort consisted of 51 healthy volunteers with no known ocular pathology. Their age ranged between 19 and 61 years old with an average age 33.9 years. The demographic, lifestyle and dietary habits were recorded for all subjects, focusing mostly on the consumption of leafy green vegetables. The answers ranged from no consumption to everyday consumption. We grouped subjects based on their answers in frequent consumers (FC), those eating leafy vegetables every day or weekly, and in infrequent consumers (IC), those with monthly or no consumption.

Results : The measured MPOD values showed an age dependence (p<0.0005) in both eyes, and therefore, the age-corrected sample was defined, where all MPOD values were normalised around a specific age value (35yo). The age corrected MPOD values for the FC group ranged from 0.29 to 0.54 D.U. with a mean of 0.39 D.U. while for the IC group ranged from 0.2 to 0.49 D.U. and a mean value of 0.35 D.U. The difference in MPOD between the two groups was small.

Conclusions : MPOD data were collected in a healthy population. The values were normalized according to age and were found to be slightly higher in the group that consumed vegetables frequently, that is on a daily or weekly basis. This finding is consistent with current bibliography stressing the positive effect of leafy green vegetables on macular pigment density values.

This is a 2021 ARVO Annual Meeting abstract.

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