The role of aging, high fat diet and blue light exposure in an experimental mouse model for basal laminar deposit formation

We sought to investigate the role of aging as a susceptibility factor for the capacity of dietary fat intake to increase the development of subretinal deposits. Mice of various ages (2, 9 and 16 months) were fed a normal diet or a diet high in saturated and unsaturated fats for a total four and a half months. Some eyes were also exposed to non-phototoxic levels of blue-green light. The outer retina and choroid were examined by light and transmission electron microscopy, and the characteristics, frequency and severity of subRPE deposits was determined. Aged mice fed normal diets developed only very mild subretinal deposits. However, many eyes of mice aged 9 months or older at the time of initiation of diet developed frequent basal laminar deposits of moderate severity, and only 16 month old mice developed more severe deposits after exposure to blue-green light. Some eyes in this older group also developed endothelial invasion into Bruch's membrane. None of the eyes developed classic drusen or linear deposits. These observations demonstrate that age increases the capacity of dietary fat, especially in the presence of environmental light, to induce subRPE deposits.