Ultrastructural alterations in the aqueous outflow pathway of adult buphthalmic rabbits.

The aqueous outflow pathway of adult rabbit eyes with congenital glaucoma (buphthalmos) was examined by light microscopy and by scanning and transmission electron microscopy. The morphology of the buphthalmic rabbit aqueous outflow pathway was markedly abnormal when examined at 6 months, 1 yr, and 2 yr displaying apparent loss and/or compression of the iris pillars, dilation of the intertrabecular spaces, loss of endothelial cell-to-cell association and disorganization of trabecular lamellae, and posterior displacement of the aqueous plexus. In addition, the trabecular meshwork lamellae were observed only adjacent to the sclera and the inner portion of the trabecular meshwork was limited to swirls of collagen with scattered cells. These morphological findings suggest that the disease process in the rabbit principally involves an alteration in the differentiation and maintenance of the structural integrity of the trabecular meshwork. The loss of structural support of the buphthalmic trabecular meshwork may be a factor in the wide variation in intraocular pressure and may allow for compression of the trabecular meshwork against the aqueous plexus.