CHANGES IN THE COLLAGENOUS MATRIX OF THE AGING HUMAN LAMINA-CRIBROSA

Aims-The age-related changes in the biochemical composition of the collagenous matrix of the human lamina cribrosa were investigated. Methods-An age range (3 weeks to 92 years old) of human laminae cribrosae, dissected free of any surrounding structures which contained collagen, were analysed for collagen solubility (n=58) total collagen content (n=46), proportion of collagen types (n=38), and collagen cross linking (n=30), using hydroxyproline analysis, scanning densitometry of peptides after cyanogen bromide digestion, and high performance liquid chromatography, respectively. Results-Age-related changes included an increase in total collagen and a decrease in the proportion of type III collagen within the lamina cribrosa. The collagen cross link pyridinoline was present at low levels, but demonstrated no trend with age. An age-related increase was found in pentosidine, an advanced glycation product. Conclusion-These changes in collagen composition imply that the mechanical properties of the lamina cribrosa are altered, resulting in a stiffer, less resilient structure with age. Such alterations in structure may contribute to the increased susceptibility of the elderly to axonal damage in chronic open angle glaucoma.