STRUCTURAL EVIDENCE FOR MEMBRANE LIPID CHANGES IN HUMAN CATARACT

Lipid changes in relationship to cataractogenesis were studied with hi stochemical methods (topoptical reactions) of polarization microscopy. Frozen sections of formaldehyde-fixed human lenses were used for thes e studies. Six lenses were transparent and 14 lenses presented early t o confluent cortical opacities. Cell membrane lipids of transparent le nses showed 8.0 +/- 2.7 nm light retardation. In the early cataractous lenses the light retardation of cell membranes was 23.3 +/- 5.0 nm an d that of the fusiform and globular lipids was 37.7 +/- 4.0 nm and 48. 5 +/- 6.9 nm, respectively. In the non transparent cortical regions of cataractous lenses, membrane lipids were not observed. Similar to oth er cell membranes, normal lens membranes are composed of loosely organ ized lipids. In early cataract lipid density uniformly increased along the cell membranes at the clinically transparent areas, while at the areas with clinically evident fine opacities, small fusiform and globu ler lipid drops were formed by even more dense lipids. Confluent corti cal cataracts were associated with disappearance of membrane lipids. I n our study our findings demonstrated intramembrane lipid changes asso ciated with cataractogenesis.