Age-related thickening of retinal capillary basement membranes

Capillary basement membrane thickness is known to increase in a variety of tissues during aging and as a consequence of certain systemic disease states. In order to determine whether capillary basement membrane thickness increases during senescence in the outer plexiform (OPL) and ganglion cell (GCL) layers of the retina, eyes of pigmented ACI rats aged 4, 11, 17, and 32 mo were examined. Basement membrane thickness in the OPL and GCL were determined at each of these ages using computer-assisted ultrastructural morphometry. Capillary basement membranes in both the OPL and GCL showed a linear increase in thickness over the 4 to 32 mo age span. The increase in thickness averaged 54% for the OPL and 65% for the GCL over this age range. At all ages examined, the GCL basement membranes were 80 to 90% thicker than those in the OPL. Age-related changes in the substructure of the capillary basement membranes differed between the OPL and GCL. It is possible that the observed age-related changes in retinal capillary basement membranes may play a role in the development of senile retinopathies.