Clinico-cytological analysis of conjunctiva and ocular surface symptoms of patients on topical anti-glaucoma medications attending Lagos University Teaching Hospital, Lagos, Nigeria: A case-control study

Background: The long-term use of topical anti-glaucoma medications is often associated with ocular surface toxicity that can affect the patient's drug compliance and quality of life. This study assessed the effect of these medications, using cytological changes of the conjunctiva and ocular surface symptoms. Materials and Methods: This was a clinic-based, case-control study that was conducted at the Lagos University Teaching Hospital that compared glaucoma patients on topical medications with age-sex-matched controls. The controls were non-glaucoma patients, who were not on any topical ocular medications at least 6 months prior to the study. The Ocular Surface Disease Index (OSDI) questionnaire was used to assess ocular surface symptoms. Schirmer's I test, tear film break-up time (TBUT) test and corneal fluorescein staining of the ocular surface were used for ocular surface disease (OSD) assessment and conjunctival impression cytology (CIC) for histological assessment and grading. Results: Six hundred and ninety-six eyes of 348 respondents, 174 cases and 174 controls, were assessed for OSD. The mean ages of the case and control groups were 56.3 +/- 12.9 years and 55.5 +/- 13.2 years, respectively, with no statistical difference (P = 0.589). All ocular parameters assessed were significantly abnormal in the case group compared to the control group. The use of topical anti-glaucoma medications was significantly associated with abnormal TBUT (P < 0.001), Schirmer's test (P < 0.001), ocular surface staining (P < 0.001), CIC (P < 0.001) and OSDI scores (P = 0.001). A significant association was seen between abnormal TBUT and the number of medications (P = 0.044, odds ratio [OR] =0.79, 95% confidence interval [CI]: 0.44-1.14), between abnormal ocular surface staining and duration of anti-glaucoma medications usage (P = 0.0104, OR = 1.2, 95% CI: 1.04-1.43) and between abnormal CIC and the duration of anti-glaucoma medications (P = 0.0007, OR = 0.7, 95% CI: 0.59-0.86). Conclusion: The study demonstrates that prolonged use of topical anti-glaucoma medications may be associated with damage to the ocular surface structures.