Abstract
Purpose::
We have used non-mydriatic, two-wavelength, autofluorescence imaging to assess concentration levels and spatial distribution patterns of macular pigment, MP, in the human retina. The purpose is to explore general characteristics such as age effects, gender differences, and correlation of pigment levels with retinal layer thickness. Also, we investigate the possibility to detect with this imaging approach potential changes in individual pigment patterns caused by nutritional supplementation and retinal pathologies.
Methods::
We quantify and spatially image the distributions of MP in the human retina with a home-built, computer-interfaced, compact CCD camera autofluorescence imaging system suitable for clinical use. The instrument permits non-mydriatic measurements with light excitations at 488 and 532 nm within a fraction of a second per image. MP images are processed and displayed in near real time. Subjects were recruited from our University’s eye clinic. They included both healthy subjects and subjects with retinal pathologies.
Results::
We measured images of more than 200 human volunteers. Image processing allowed us to obtain spatially resolved MP levels, MP levels integrated over the whole distribution, and MP line plots along meridional lines. We find distinctly differing distribution patterns of MP in different individuals, including distributions that are predominantly concentrated in the foveola (35%), distributions that are spatially extended further into the perifovea (25%), distributions with ring-shaped MP patterns (33%), and distributions with very low levels (7 %). Ring radii can vary significantly between subjects. Integrated MP levels differ strongly between individuals, and on average decrease by ~50% from young to old age (30-80). Retinal pathologies can lower the MP levels at any location within the MP distribution and/or produce spatial redistributions over time. Reproducibility of the MP imaging is sufficiently tight (~5 %) to allow for the tracking of MP level changes upon supplementation. All MP distribution patterns appear equally often in women and men.
Conclusions::
Autofluorescence imaging is an objective quantitative noninvasive optical technique suitable for rapid screening of MP levels and distributions without the need for pupil dilation. It is well suited to investigate MP properties in human subjects and to track changes in MP levels and distributions occurring with aging, with nutritional supplementation, and with degenerative diseases.
Keywords: macular pigment