The Impact of Glaucoma Medications on Corneal Wound Healing

Abstract

Purpose: To evaluate the impact of antiglaucoma drugs on the corneal healing process and corneal toxicity.

Materials and methods: Four eye drops to treat glaucoma--Xalatan (latanoprost 50 μg/mL; Pfizer), Monoprost (latanoprost 50 μg/mL; Théa Pharma), Taflotan Sine (tafluprost 15 μg/mL; Santen Pharmaceutical Co.), Travatan (travoprost 40 μg/mL; Alcon), and 0.02% benzalkonium chloride (BAC) solution and HyloComod (1 mg/mL sodium hyaluronate; Ursapharm) as positive and negative control were tested regarding corneal irritability and effect on corneal healing. Formulas were tested over 3 days and administered 6 times daily on rabbit corneas cultured on an artificial anterior chamber (the Ex Vivo Eye Irritation Test system). Initially, 4 corneal abrasions (2.5 to 5.7 mm2) were applied. All defects were monitored during drug application by fluorescein stains and photographs. Glucose/lactate concentrations were monitored for corneal metabolic activity evaluation.

Results: For Xalatan and BAC, the corneal erosion size increased from 14.65 to 66.57 mm2 and 14.80 to 87.26 mm2. Travatan and Taflotan Sine did not interfere with corneal healing. Monoprost delayed corneal healing. For Xalatan and BAC, histology showed severe alteration of the superficial cornea. An increase in anterior chamber lactate concentration indicates corneal toxicity for Xalatan, BAC, and Monoprost.

Conclusions: Corneal toxicity of Xalatan is most probably caused by BAC. Monoprost delays corneal healing, which is not well understood. The Monoprost effects could be caused by its additive, macrogolglycerolhydroxystearate 40. This excipient is a known skin irritant, and its concentration is relatively elevated in Monoprost, 50 mg/mL, compared with its active ingredient, latanoprost (0.05 mg/mL).