Histological and Immunohistochemical Study of the Effect of Travoprost with and without Benzalkonium Chloride on the Corneal Epithelium of Adult Male Albino Rat

Introduction: Chronic topical glaucoma therapy has been reported to cause deleterious changes to the ocular surface layers. Benzalkonium chloride (BAK) is the most commonly used ocular preservative, especially in antiglaucoma drugs. It is largely responsible for the ocular toxicities and inflammation associated with the chronic usee of many ophthalmic solutions. Aim of the Work: This work aimed to compare structural changes in corneal epithelium of rats after chronic exposure to travoprost 0.004% eye drops preserved without BAK, travoprost 0.004% eye drops preserved with BAK and BAK alone. Materials and Methods: Forty adult male albino rats were divided into five equal groups and treated topically once daily for eight weeks; group I (control group), group II received sofzia preservative system, group III received travoprost 0.004% eye drops preserved with sofzia (Travatan Z), group IV received BAK 0.015% and group V received travoprost 0.004% eye drops preserved with 0.015% BAK (Travatan). At the end of the experiment, corneal specimens were processed for histological study by light and electron microscopes as well as immunohistochemical study with monoclonal antibody to cytokeratin-3 (CK-3). Results: Corneal epithelium of animals treated with BAK alone and those treated with travoprost preserved with BAK showed desquamation of epithelial cells, significant decrease of epithelial thickness, focal disruption of Bowman’s membrane, loss of microvilli, cytoplasmic vacuolation, nuclear fragmentation and swollen mitochondria with widening of intercellular spaces. Immunohistochemical study revealed significant decrease in the expression of CK-3 in the cytoplasm of epithelial cells. However, no oblivious histological changes were recorded in corneal specimens in animals treated with travoprost preserved with sofzia with normal expression of CK-3 in the cytoplasm of epithelial cells. Conclusion: Once-daily dosing of travoprost preserved with BAK produced significant corneal epithelial changes. However, the use of glaucoma medications with alternative preservatives as sofzia can preserve corneal health.