Evaluation of corneal epithelial thickness by anterior segment optical coherence tomography in glaucoma patients receiving topical prostaglandin and dry eye treatment.

PURPOSE: To evaluate corneal epithelial thickness (CET) and tear break-up time (TBUT) in glaucoma patients receiving prostaglandin monotherapy and concurrent dry eye treatment, grouped according to the benzalkonium chloride (BAK) concentration levels of their eye drops, and to compare pre- and post-treatment measurements.

METHODS: Eighty-two glaucoma patients with dry eye development while receiving prostaglandin monotherapy were included in this study. Patients were divided into three groups based on BAK exposure: Group 1 used two BAK-containing drops, Group 2 used one BAK-containing and one BAK-free drop, and Group 3 used only BAK-free drops. CET was measured by anterior segment optical coherence tomography (AS-OCT) within a 6-mm corneal diameter divided into 17 sectors. Comprehensive ophthalmic examinations and TBUT measurements were performed at each visit.

RESULTS: No significant differences were found among the groups in terms of age, sex, follow-up time, or intraocular pressure (p > 0.05). In Group 1, significant epithelial thinning was observed in the central 2 mm, paracentral 2-5 mm superior and nasal sectors, and mid-peripheral 5-6 mm nasal and inferior sectors (p < 0.05). In Groups 2 and 3, minimal changes were not significant (p > 0.05). TBUT differed significantly between groups at both visits (p < 0.001) and showed a weak positive correlation with CET changes (r = 0.291, p < 0.05).

CONCLUSION: Significant corneal epithelial thinning was found only in patients using two BAK-containing drops. Despite receiving dry eye treatment, TBUT remained below normal in this group, possibly due to BAK's toxic effects on the tear film and epithelial cells. Monitoring CET by AS-OCT may help detect early signs of dry eye in clinical practice.