The relationships of age changes in retinal pigment epithelium and Bruch'smembrane

PURPOSE. TO study the correlations between age, Bruch's membrane (BM) thick ness, retinal pigment epithelial (RPE) autofluorescence, and RPE residual b ody content. METHODS. Eight-millimeter-diameter macular discs from 88 unpaired human eye bank eyes were obtained within 72 hours of death, fixed in 10% neutral buf fered formalin, and hemisected horizontally. One portion of the macular dis c was embedded in paraffin and stained with periodic acid-Schiff for the me asurement of BM thickness. RPE autofluorescence measurements were performed on unstained, deparaffinized sections. A second portion of the macular dis c was prepared for electron microscopy to evaluate RPE residual body conten t. Linear and polynomial regression techniques were used to investigate the correlations between age, BM thickness, RPE autofluorescence, and RPE resi dual body content. RESULTS. Bruch's membrane thickness increased with age according to the lin ear model. RPE autofluorescence and RPE residual body content also increase d with age, but the correlations were best approximated by a quadratic mode l. The correlations between RPE autofluorescence and residual body content and between BM thickness and RPE autofluorescence were best approximated by a linear regression model. There was considerable variation in these corre lations between specimens and within the same age group. CONCLUSIONS. Although the changes in RPE and Bruch's membrane increased wit h age and there was a direct correlation between changes in the two tissues , there was considerable variation within each age group and between specim ens. This probably reflects the multifactorial nature of the process.