Aging human RPE: morphometric analysis of macular, equatorial, and peripheral cells.

TLDR

The study examined RPE from 50 human eyes spanning five decades using ultrastructural morphometry, quantifying lipofuscin, melanin, and complex granules in macular, equatorial, and peripheral regions, and computationally analyzing age‑related changes and fixation delay effects. Lipofuscin granules increased most rapidly between the first and second decade and continued to rise with age, while pure melanin decreased and complex melanin granules increased; macular RPE had more complex granules than non‑macular, free cytoplasmic space shrank with age, and fixation delays up to 9 h had no significant impact, providing a baseline for normal human RPE.

Abstract

Retinal pigment epithelium (RPE) of 50 human eyes, five from each 10 decades of life, were analyzed using ultrastructural morphometric techniques. Content of three types of pigments, lipofuscin, melanin, and complex granules, (melanolipofuscin, melanolysosomes) were recorded for cells from macular, equatorial, and peripheral retinal specimens. Areas occupied by pigments, nucleus, and cytoplasmic space were calculated. Data were analyzed by a computer for age-related changes and effects of fixation delay time. The largest increase in lipofuscin granules occurred between the first and second decade of life, and further increases occurred with age. The content of "pure" melanin declined with age, whereas the number of complex melanin granules increased. Macular RPE contained more complex granules than nonmacular RPE, particularly in young eyes. The volume of RPE cytoplasm not occupied by pigments ("free space") decreased with age. No significant effects of fixation delays between 2 and 9 hours postmortem were found on the parameters studied here. These findings may serve as a baseline for estimating normalcy of human RPE specimens.