Age-related changes of microfibrils in the cornea and trabecular meshwork of the human eye.

Microfibrils in the connective tissue can be subdivided into two classes, elastin-associated and elastin-independent microfibrils. The distribution of microfibrils of both classes were studied in the anterior segment of the human ocular tissues, with a view to examine age-related morphological changes. In the trabecular meshwork of infants, the tubular structure of microfibrils was identified and the fibrils were associated with elastin, forming a typical elastic fiber. This was confirmed by the tannic acid-uranyl acetate staining which reacts specifically with elastin. In the cornea, microfibrils were detected in the deep stroma of the infant. They were not associated with elastin (elastin-independent microfibrils). In the glaucomatous eye of a 7-year-old boy, microfibrils were indistinct in the trabecular meshwork. In the corneal stroma of the same eye, microfibrils were observed, but the occurrence was rarer than in the nonglaucomatous infants examined in this study. In the trabecular meshwork of aged persons, no tubular or fibrillar structure was seen around the elastin. Microfibrils were not observed in the cornea. The morphological features and occurrence of microfibrils change with age in the anterior segment of the human eye. Thus microfibrils can be a good indicator for the age-related changes in these tissues.