these results suggest that BCMO1 and CD36 are implicated in plasma and retina concentrations of lutein and that genetic variants in these genes can modulate blood and retina concentrations of lutein.

Clinical studies of photoreceptor orientation are limited by the fact that psychophysical methods for measuring the Stiles-Crawford effect are time consuming and require excellent co-operation from the subject. We have developed a novel instrument, the photoreceptor alignment reflectometer (PAR), that determines photoreceptor alignment by measuring the distribution in the pupil of light reflected by one retinal location. This determination is accomplished in a measurement time of 4 sec and requires minimal co-operation from the subject. The technique is not significantly affected by reflections at the limiting membrane, or by changes in entrance and exit pupil configuration, or by location of bleaching light entry. The PAR was used to measure the orientation of foveal photoreceptors, their directionality, and the ratio of directional to diffuse flux in 20 normal subjects ranging in age from 20 to 60 yr.

No abstract

Light reflected specularly by the inner limiting membrane (ILM) provides information on the topography of the retinal surface. The ILM in the central part of the foveal pit acts as a concave mirror. Light reflected specularly by this mirror forms an image of the entrance pupil in front of the retina. In 15 normal subjects (ages 16-56 years) we have measured photometric and geometrical-properties of this image to derive two characteristics of the ILM: its reflectance rho at the foveola and its radius of curvature r in the central part of the fovea. rho and r are found to decrease significantly with age (p = 0.0073 and p = 0.01, respectively). The equations of the regression lines are log10 rho = -4.234 - 0.0118 age and radius r = 1484 - 13.6 age, respectively (age in years, r in micrometers).