Effect of preservative-free and preserved prostaglandin analogues on the histology of cornea of adult male guinea pigs following repeated exposure

Background: Glaucoma is a group of eye diseases that can cause vision loss. Prostaglandin analogues (PGAs) are known to be first-line treatment for patients with glaucoma. Latanoprost is a good, efficient and well-tolerated PGA that is currently available as latanoprost with benzalkonium chloride (BAC) (Xalatan) and preservative-free (PF) prostaglandin analogue latanoprost (Monopost). Lately, using PF anti-glaucoma agents has been considered an essential procedure for enhancing glaucoma care. This study aimed to analyse the histological changes within the corneal tissue with the use of currently available preserved prostaglandins-derived eye drops and PF prostaglandin analogue.

Materials and methods: In this study, 40 male guinea pigs were divided into four equal groups. Control group, Latanoprost with 0.02% BAC-treated group, Recovery group and PF latanoprost-treated group. After 2 months, the corneal tissues of guinea pigs were prepared for light and electron microscopic studies; morphometric and statistical studies were performed.

Results: Our results indicated that guinea pigs treated with latanoprost with BAC exhibited ocular surface changes: there was epithelial thinning with desquamation, the stroma showed irregularly arranged collagen fibres and small keratocytes. Morphometrically, there was a marked decrease in the thickness of epithelium and number of keratocytes. Negative periodic acid Schiff (PAS) reaction was observed in some parts of the epithelial basement membrane. The epithelium gave a strong positive immunoreactivity for Bcl-2-associated X protein (BAX). Guinea pigs left to recover exhibited improvement, while treatment of animals with PF latanoprost resulted in nearly normal corneal structure.

Conclusions: In conclusion, PF prostaglandin anti-glaucoma medication seems to be better and have protective effect on cornea of male guinea pigs than prostaglandins with BAC preservative.