Light distributions on the retina: relevance to macular pigment photoprotection.

Abstract

Light exposure has been implicated in age-related macular degeneration (AMD). This study was designed to measure cumulative light distribution on the retina to determine whether it peaked in the macula. An eye-tracker recorded the subject's field of view and pupil size, and superimposed the gaze position. Fifteen naïve subjects formed a test group; 5 formed a control group. In phase 1, all subjects viewed a sequence of photographic images. In phase 2, the naïve subjects observed a video; in phase 3, they performed computer tasks; in phase 4, the subjects walked around freely. In phase 1, control subjects were instructed to gaze at bright features in the field of view and, in a second test, at dark features. Test group subjects were allowed to gaze freely for all phases. Using the subject's gaze coordinates, we calculated the cumulative light distribution on the retina. As expected for control subjects, cumulative retinal light distributions peaked and dipped in the fovea when they gazed at bright or dark features respectively in the field of view. The light distribution maps obtained from the test group showed a consistent tendency to peak in the macula in phase 3, a variable tendency in phase 4, but little tendency in phases 1 and 2. We conclude that a tendency for light to peak in the macula is a characteristic of some individuals and of certain tasks. In these situations, risk of AMD could be increased but, at the same time, mitigated by the presence of macular carotenoids.

Multi-nucleate retinal pigment epithelium cells of the human macula exhibit a characteristic and highly specific distribution

“…The distribution of incident light, often invoked as a mechanism behind topographic differences in the retina, is fairly even across the fundus out to 50 deg of eccentricity and thus does not explain variation within the 6 mm diameter macula (21 deg of vision) (Kooijman, 1983; Pflibsen et al . , 1988; Bone et al, 2012).…”

Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina

“…Such data would provide valuable information on whether such activities can put the retina at risk of light-induced injury. The feasibility of such measurements with an eye-tracker and a camera capturing the images in the visual field was shown already in 2012 by Bone et al but also revealed the challenges of quantitative measurements of the absolute illuminance values using a scene camera with a small dynamic range [525,526]. Overcoming these challenges and adding spectroradiometric measurements and the measurements of the transmission of the lens, would enable the calculation of the spatial distribution of the retinal spectral irradiance in the absolute values.…”