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Aging of the Retinal Pigment Epithelium

Michael E. Boulton

CONTENTS

INTRODUCTION

AGIING CHANGES IN THE FUNDUS

AGE-RELATED CHANGES IN RPE MORPHOLOGY

FUNCTIONAL CONSEQUENCES OF RPE CELL AGING

OXIDATIVE STRESS AND RPE AGING

THE RELATIONSHIP BETWEEN AGING AND RETINAL PATHOLOGIES

SUMMARY AND CONCLUSIONS

REFERENCES

INTRODUCTION

The retinal pigment epithelium (RPE) is a hexanocuboidal monolayer of cells located between the neural retina and the choroid (Fig. 1). The RPE plays a critical role in ensuring the function and survival of the overlying photoreceptor cells [1, 2]. The functions of the RPE include (1) establishment of a blood retinal barrier that regulates transepithelial transport of nutrients and waste products to and from the photoreceptors; (2) the transport and storage of retinoids; (3) phagocytosis and degradation of spent photoreceptor outer segment tips; (4) absorption of optical radiation that has passed through the neural retina; (5) protection of the outer retina from damage by reactive oxygen species (ROS); (6) the production of growth factors and cytokines; (7) maintenance of the choriocapillaris. The structure and function of the RPE varies depending on retinal location (i.e., macula vs. periphery) [1–4]. RPE cells in the macula measure about 14 mm in diameter, while those toward the periphery can measure up to 60 mm in diameter, with cell size and shape becoming particularly irregular [3, 5, 6]. Macular RPE cells, which cover an area of around 5-mm diameter, are likely to be the most metabolically active since they are located in a region critical for visual function. The RPE is a normally nondividing cell layer throughout life and thus accumulates cellular damage, which can eventually result in structural and functional changes.

From: Ophthalmology Research: Visual Transduction and Non-Visual Light Perception

Edited by: J. Tombran-Tink and C. J. Barnstable © Humana Press, Totowa, NJ

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