The importance of cellular changes in the conjunctiva of patients with uveitic glaucoma undergoing trabeculectomy.

The results of trabeculectomy in patients with glaucoma secondary to uveitis are poor, but the exact cause of this remains unknown. Therefore, a study was undertaken to determine differences between conjunctiva from patients with glaucoma secondary to uveitis and that from patients with primary open angle glaucoma. Conjunctival biopsies from three patient groups were quantitatively analysed by light microscopy. Group A consisted of 10 patients with glaucoma secondary to uveitis who, prior to surgery, had been treated with topical steroids and topical beta-blocker drugs. Control groups (groups B and C) each consisted of 10 patients with primary open angle glaucoma for whom primary trabeculectomy (group B) or trabeculectomy following failure of topical beta-blockers alone (group C) was planned. Treatment with topical beta-blocker drugs was found to redistribute mast cells within the conjunctiva but to have no significant effect on cell numbers. In comparison with either control group, uveitic conjunctiva was found to contain significantly more fibroblasts, lymphocytes and macrophages. It is possible that these differences are responsible for an enhanced risk of excessive external bleb fibrosis, failure of filtration surgery and poor results with adjunctive 5-fluorouracil.