Abstract
Purpose: :
To investigate toxic effects of the topical glaucoma medications on the ocular surface and to verify whether the corneal toxicity is from therapeutic active compounds in formula or the preservatives per se.
Methods: :
This cross sectional study included 302 eyes of 174 patients who had been taking the same topical anti-glaucoma drugs for at least 8 weeks. Study group was divided into subgroups by the type of active compounds and the presence of beta-blocker. The effect of various of prostaglandin formula(latanoprost vs travoprost) and the effect of various active compounds(carbonic anhydrase inhibitor vs prostaglandin) were compared on the ocular surface. The effect of the various combination formula depending on the presence of beta-blocker(trusopt vs cosopt; xalacom vs xalatan) was also compared. The cumulative effect of the dosage of the benzalkonium chloride was analyzed on the dry eye. Tear break-up time(BUT) and grading of corneal epithelial erosion(CEE) were compared between these subgroups.
Results: :
The CEE was found in 30.4% of eyes and moderate to severe erosion was found in 9.9%. Shorter BUT less than 10 seconds was revealed in 59.3% of eyes. There was no significant difference in BUT and CEE between latanoprost and travoprost, and between dorzolamide and travoprost. Xalacom® presented significantly severe CEE than Xalatan® and ,Cosopt® showed significantly shorter BUT and more severe CEE than Trusopt®. Cumulative dosage of benzalkonium chloride was directly proportional to CEE (p=0.002), and was inversely related to BUT(p=0.025).
Conclusions: :
Topical Beta-blocker in combination formula appeared to have an corneal toxic effects as an active compound per se as well as the benzalkonium chloride did.
Keywords: cornea: epithelium • drug toxicity/drug effects