Purpose. Previous studies showed that lutein and zeaxanthin, the major human retinal carotenoids, are concentrated in the macula. In this study, the carotenoids in human macular and peripheral retina and the retinal pigment epithelium (RPE) were analyzed. They were also determined in the rod outer segments (ROS) before and after removal of extrinsic membrane proteins. Methods. Carotenoids were extracted from the macular and peripheral sections of human retina and RPE with hexane in dim light and analyzed by high performance liquid chromatography (HPLC). ROS samples equivalent to the amount in a single retina were also analyzed. Results. Retinal carotenoid amounts were similar to previous reports, but only low levels were detected in the RPE. Regional ratios of lutein:zeaxanthin were similar in the retina and RPE. Approximately 25 of the total retinal carotenoids were found in the ROS, indicating that a substantial portion of peripheral retinal carotenoids are present in the ROS. However, after removal of the extrinsic membrane proteins and subsequent analysis, carotenoids were not detected. Conclusions: Most of the carotenoids in the human peripheral retina are present in the ROS. These ROS carotenoids are associated with soluble or salt-dependently bound proteins.
Bibliographical noteFunding Information:
The authors thank the Montana Eye Bank for making the human eye samples used in this study available. This work was supported by a grant from the National Eye Institute (EY– 00983) to DSK, and by a grant from the German Academic Exchange Service (DAAD, #D–94–20537) to OS. Dr. van Kuijk is a Research to Prevent Blindness William & Mary Greve Scholar.
- Retinal pigment epithelium (RPE)
- Retinal rod outer segments (ROS)
- Vitamin E