Morphological Changes of Trabeculectomy Specimens in Different Kinds of Uveitic Glaucoma

Abstract

Purpose: To analyze morphological changes in trabeculectomy specimens of patients suffering from uveitic secondary open angle glaucoma (UG).

Material and Methods: Trabeculectomy specimens of six patients suffering from uveitis for 2 to 19 years and having been treated with steroids for 5 to 86 months were obtained during antiglaucomatous surgery after failed antiglaucomatous drug treatment. Six specimens, four from patients with Fuchs’ heterochromic cyclitis (FHC), one with Herpes simplex-associated uveitis (HS), and one with juvenile idiopathic arthritis-associated uveitis (JIA) were analyzed by light and electron microscopy. Deposits of extracellular material (ECM) underneath the inner wall of Schlemm’s canal (SC) were analyzed quantitatively.

Results: In the patients with FHC, most trabecular beams were thickened by fibrillar material deposited between trabecular cells and basement membranes. Some single lamellae appeared to be destroyed. Underneath the inner wall endothelium there was an increase of “plaques” morphologically comparable to those seen in patients with primary open angle glaucoma. The specimen with JIA showed also “plaque” accumulations at the inner wall and thickening of the trabecular beams, but the latter was due to thickening of the basement membrane itself with inclusions of long-spacing collagen. In the specimen with HS, large amounts of fingerprint-like basement membrane material were found between the trabecular lamellae. The subendothelial region displayed an increase in plaques and fibrillar material.

Conclusions: In all specimens derived from patients with UG, there was an increase in ECM in the subendothelial region of SC, presumably contributing to the elevations in intraocular pressure. The trabecular meshwork also exhibited signs of lytic activity, but this was much less prominent than the thickening of the lamellae due to ECM deposits surrounding the central cores of the lamellae.

Keywords::

• Electron microscopy
• Glaucoma
• Trabeculectomy
• Ultrastructure
• Uveitis

ACKNOWLEDGMENTS

The authors wish to thank Anke Fischer, Gertrud Link, and Hong Nguyen for excellent assistance with electron microscopy and Jörg Pekarsky and Marco Gößwein for preparing the micrographs.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.