hydroxylysine and Glaucoma

The purpose of this study was to compare collagen content in the TM of normal and glaucomatous eyes, and to establish whether collagen levels change with age. Collagen content was measured in 30 normal and 27 age matched glaucoma trabeculectomy specimens by the sirius red dye binding technique, and in 14 normal and 15 age matched glaucoma specimens by amino acid analysis. Both dye binding data and amino acid analysis showed no statistical difference between normal and glaucoma samples. Age had no significant effect on mean optical densities or on the collagen-specific amino acids proline, hydroxyproline, and hydroxylysine. Amino acid variability, however, was statistically different between the two groups. These results indicate that mean collagen levels in the trabecular meshwork of glaucomatous eyes do not differ from those in normal eyes.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Amino Acids; Collagen; Glaucoma; Humans; Hydroxylysine; Hydroxyproline; Middle Aged; Proline; Trabecular Meshwork

The pressure theory is still predominant in explaining the pathophysiology of the chronic open angle glaucoma. An insufficient drainage system resulting in an increased intraocular pressure is the basis for this theory. The pressure will exert an effect upon the optic disc which either directly on the nerve fibres or indirectly via the vascular system will result in a characteristic optic atrophy. The collagen fibres, both in the trabecular meshwork of the anterior chamber and in the lamina cribrosa of the optic disc, form a mesh through which the aqueous humour and the nerve fibres, respectively, pass through the wall of the eye. A hypothesis explaining the pathophysiology of this disease, and based on the assumption that there is a primary change in the collagen molecules, resulting in a weaker structure than normal both in the trabeculae and in the laminae, is forwarded. The structures analysed for the content of hydroxyproline, hydroxylysine and proline were the trabecular meshwork, the sclera and the lamina cribrosa. Three categories of autopsy eyes were studied, i.e. normal eyes, glaucomatous eyes, and eyes under a suspicion of glaucoma. In the normal eyes, the collagen composition in the trabecular meshwork was different from that in the sclera and the lamina cribrosa. There is also a difference in the composition between the sclera and the lamina cribrosa. In glaucoma, the content and/or the composition of the collagen molecules in the lamina were significantly changed. In the eyes under suspicion of glaucoma the same changes as in the glaucomatous eyes could be demonstrated. However, 5 of the 7 eyes in this category had no demonstrable nerve atrophy. The findings suggest that the change in collagen pattern is primary. This study has not demonstrated which types of collagen are present or the physical properties of this collagen. Further tests to demonstrate the different types of collagen and their rigidity are planned.

Topics: Aged; Collagen; Female; Glaucoma; Glaucoma, Open-Angle; Humans; Hydroxylysine; Hydroxyproline; Male; Optic Disk; Proline; Sclera; Skin; Trabecular Meshwork

Topics: Adult; Aged; Connective Tissue; Female; Glaucoma; Glycosaminoglycans; Humans; Hydroxylysine; Hydroxyproline; Male; Middle Aged; Monoamine Oxidase