Age related changes in extracellular materials in the inner wall of Schlemm's canal.

An electron microscopic investigation was conducted to study the extracellular materials of the endothelial meshwork in the human outflow apparatus. A quantitative analysis was made to determine the changes which occur with age. Tissue from 20 cases, ages 4 months to 80 years, was examined. A morphometric technique which utilised a grid of 100 random points was used to estimate the percentage area of extracellular components in the endothelial meshwork. It was found that while the percentage area occupied by amorphous ground substance and fibrillar material decreased with age, the percentage area occupied by the electron-dense component increased. Variation in distribution of these components was noted both between cases of similar age and also within one section. A qualitative description of other changes in the trabecular meshwork is given, and the limitations of the technique are discussed.