[Biochemical and histochemical analysis of age related lipid deposits in Bruch's membrane]

In histochemical studies the age-related deposition of different lipids in Bruch's membrane has been seen. This is important for the pathogeneses of age-related macular degeneration due to changes in diffusion characteristics. Because the specificity of histochemical results is limited, a correlation of histochemical lipid analysis with biochemical methods was performed. The macular Bruch's membrane of 27 donors (age 1-97 years) was analyzed. The results of this analysis demonstrated that the increasing histochemical staining for lipids in Bruch's membrane corresponded with an increasing amount of lipids extracted from Bruch's membrane in biochemical analysis. This lipid deposition progressed exponentially with age. However, a large variation in the type of lipid deposited could be observed, with predominant deposition of phospholipids in some eyes and of neutral lipids in others. Furthermore, the phospholipids extracted were differentiated into 50% phosphatidylcholine, 30% phosphatidylethanolamine and 20% phosphatidylinositol and phosphatidylserin. The deposition of lipids, especially neutral lipids, in Bruch's membrane may change its diffusion characteristics. This appears to be important for the pathogenesis of age-related pigment epithelium detachments. The composition of the phospholipids extracted from Bruch's membrane supports, furthermore, the concept that the material deposited is the result of metabolic limitations in the degradation of photoreceptor outer segment material.