Comparative Evaluation of Preservative-Free and Preserved Antiglaucoma Eye Drops

Abstract

Background: Long-term topical therapy is central to glaucoma management, but repeated exposure to preservatives, particularly benzalkonium chloride (BAK), may contribute to ocular-surface symptoms and signs. Preservative-free (PF) formulations may improve tolerability while maintaining intraocular-pressure (IOP) control.

Objective: To compare longitudinal IOP and ocular-surface measures, recorded adverse events, and treatment discontinuation among patients receiving PF or BAK-preserved antiglaucoma eye drops.

Methods: This prospective comparative observational study included 130 patients in the dataset: 78 receiving BAK-preserved drops and 52 receiving PF drops. Outcomes were summarized at baseline and months 1, 3, 6, and 12. Measures included IOP, Ocular Surface Disease Index (OSDI), tear-film break-up time (TBUT), Schirmer test, Oxford staining grade, conjunctival hyperemia, adverse events, and discontinuation. The study summary provides descriptive data but no dispersion estimates or inferential test results.

Results: Mean IOP decreased from 23.4 to 16.0 mmHg in the BAK group and from 24.4 to 17.6 mmHg in the PF group by month 12. In the BAK group, OSDI increased from 17.1 to 26.4, TBUT declined from 8.9 to 6.0 seconds, Schirmer values declined from 13.6 to 11.1 mm, Oxford grade increased from 0.79 to 1.54, and hyperemia score increased from 0.87 to 1.70. In the PF group, OSDI decreased from 20.2 to 18.0, TBUT increased from 8.3 to 9.0 seconds, Schirmer values were 12.8 and 13.2 mm, Oxford grade changed from 0.92 to 0.78, and hyperemia score from 0.90 to 0.68. Recorded adverse-event counts were 85 and 22, respectively. Adverse-event-related discontinuation was recorded for 16/78 (20.5%) in the BAK group and 3/52 (5.8%) in the PF group.

Conclusion: PF treatment was associated with more favorable ocular-surface trends and fewer recorded adverse-event-related discontinuations. Both groups showed lower mean IOP, with no statistically significant between-group difference in IOP change. These observational findings do not establish causality; active ingredients, baseline ocular-surface differences, and incomplete follow-up should be considered.