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M Fratto, G Scorcia, V Scorcia, V Piccirillo, G Carnovale-Scalzo, F Scarinci, F Borelli, A Scarpelli, J Feher; Microangiopathy of the Human Choroid in Age-Related Macular Degeneration. . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1304.
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Purpose: Thickening of retinal capillary wall is a well known age-and diabetes-related histological phenomena. Although, the role of choroidal blood flow in age-related macular degeneration is well established, the analog alterations of the choroidal vessels are poorly explored. The aim of our studies was to learn more on the pathology of choriocapillaries and small choroidal vessels in normal aging and in age-related macular degeneration (AMD). Methods: Thirty-four human retinas (17 affected by various degree of AMD and 17 age and sex matched controls) were studies by electron and polarization microscopy Results: In normal conditions choriocapillaries are composed of a «fenestrated» endothelial tube surrounded by a thin basement membrane. In contrast to retinal capillaries, pericytes rarely occur and their processes were never found at the inner side of the choriocapillaries (next to the Bruch’s membrane) suggesting that pericytes may play an insignificant role in the function of choriocapillaries. In aged eyes slight and diffuse thickening of choriocapillary basement membranes was observed. In AMD focal thickening of the basement membrane was frequently observed. It is due to addition of either homogeneous material or collagen fibres to the basement membrane. These alterations were observed predominantly at the inner side of choriocapillaries. A similar thickening was found in the basement membrane of retinal pigment epithelium (RPE). Sometimes cytoplasmic processes of pericytes were also observed in the thickened basement membranes. Several choroidal arterioles showed narrowing due to deposition of basement membrane-like material in their wall Conclusion: Our observations suggested that, besides the well known Bruch’s membrane alterations, in AMD exists a choroidal microangiopathy which may be responsible for the abnormal choroidal blood flow seen in this disease. Accumulation of abnormal basement membrane affected the basement membrane of RPE, choriocapillaries and small choroidal arteries. These alterations may have a common metabolic background.
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