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Changes in the collagenous matrix of the aging human lamina cribrosa
J Albon1, W S Karwatowski, N Avery
1Department of Ophthalmology, University of Bristol, Bristol Eye Hospital, Bristol.
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.