MORPHOMETRIC ANALYSIS OF BRUCHS MEMBRANE, THE CHORIOCAPILLARIS, AND THE CHOROID IN AGING

Purpose. To quantify changes in choriocapillary density and in thickne ss of Bruch's membrane, the choriocapillaris, and the choroid in 95 un paired, histologically normal human maculae aged 6 to 100 years and in 25 maculae with advanced age-related macular degeneration. Methods. L ight microscopic, computer-aided, morphometric quantitative analysis. Results. In ten decades, Bruch's membrane thickness increased by 135%, from 2.0 to 4.7 mu m; the choriocapillary density decreased by 45%; t he diameter of the choriocapillaris decreased by 34%, from 9.8 to 6.5 mu m; and the choroidal thickness decreased by 57%, from 193.5 to 84 m u m in normal maculae. In maculae with basal laminar deposit, geograph ic atrophy, or disciform scarring, the density of the choriocapillaris was 63%, 54%, and 43% of normal and the choriocapillary diameter was 81%, 73%, and 75% of normal, respectively. Choroidal thickness remaine d unchanged. Conclusions. Thickness of Bruch's membrane was only relat ed to age (r(s) = 0.63) and not to age-related atrophy of the chorioca pillaris. Age was also the strongest factor related to choriocapillary density (r(s) = -0.58). In advanced stages of age-related macular deg eneration, the decrease in choriocapillary density and diameter was si gnificantly larger than in normal maculae, but the thickness of the ch oroid and Bruch's membrane was the same. The latter was significantly thinner (81% of normal) in disciform scarring.