The effect of topical cholinergic medications on human Tenon's capsule fibroblasts in tissue culture.

Abstract

The prior long-term use of topical anti-glaucoma medications has been suggested as an adverse factor for the outcome of trabeculectomy. The mechanism of action is not known. This study investigates the effect of cholinergic medications on the proliferation and viability of human Tenon's capsule fibroblasts in tissue culture to see whether this may be one mechanism by which increased surgical failure occurs. We examined the effect of two commercial pilocarpine products, pure pilocarpine hydrochloride, and pure benzalkonium chloride, at various dilutions, on the proliferation (as assessed by 3H-thymidine uptake) and viability (assessed microscopically) of human Tenon's capsule fibroblasts in tissue culture. None of the tested compounds stimulated the proliferation of fibroblasts in tissue culture. Three of the compounds inhibited proliferation, and all compounds had toxic effects on cell morphology. At equivalent dilutions of commercially available concentration, pure benzalkonium chloride and the commercial product containing it appeared more toxic and antiproliferative to cells in culture than pure pilocarpine hydrochloride and the preservative-free commercial product. These results show an antiproliferative and toxic effect of medications on fibroblasts in tissue culture. They do not support the theory that topical medications directly stimulate fibroblast proliferation. The possible relevance of these results for the outcome of glaucoma surgery is discussed.