Understanding Ocular Surface Disease in Glaucoma: A Comparative Analysis of Symptoms and Objective Parameters.

Background Glaucoma is a progressive optic neuropathy that may result in irreversible visual impairment and can diminish quality of life. Lowering intraocular pressure (IOP) through topical eyedrops is usually the primary approach to managing glaucoma. However, long-term treatment poses a risk to ocular surface health, leading to ocular surface disease (OSD). Preservative-containing eyedrops are implicated in OSD development due to their detrimental effects on the tear film and goblet cell density. OSD symptoms may impact patient compliance due to local side effects. This study aims to assess OSD in glaucoma patients receiving topical treatment, quantify symptoms and objective ocular surface parameters, and compare them to a control group not using topical glaucoma medications. Methodology Patients diagnosed with primary open-angle glaucoma receiving topical treatment and a control group were included in this study. To assess OSD, patients completed the Ocular Surface Disease Index (OSDI) questionnaire to evaluate symptoms and underwent objective measurements of ocular surface parameters using a keratograph. These parameters included assessments of bulbar redness and non-invasive keratograph tear break-up time (NIKTBUT). Results A cohort of 92 patients was subjected to examination, comprising 66 individuals diagnosed with glaucoma and 26 controls. Within the glaucoma patient subset, the mean number of IOP-lowering drugs administered was 2.42 ± 0.18, with 22.7% exclusively utilizing preservative-free eye drops. Our investigations unveiled a substantial prevalence of OSD symptoms, manifesting not only within the glaucoma cohort but also among the control group, with 72.7% and 53.8%, respectively (p = 0.224), reporting moderate-to-severe symptoms (OSDI > 23). Remarkably, OSDI scores exhibited higher values among female participants (p = 0.039) and glaucoma patients using prostaglandins (p<0.001) and were negatively correlated to the number of IOP-lowering drugs used (-0.448; p < 0.001). Furthermore, employing keratograph assessment, we discerned heightened bulbar redness (1.86 ± 0.07) in the glaucoma group compared to the control group (1.58 ± 0.07; p = 0.008). Glaucoma subgroup analyses further unveiled higher bulbar redness among glaucoma patients employing carbonic anhydrase inhibitors (p = 0.035) and applying medication preservatives (p = 0.045) but lower among individuals using beta-blockers (p = 0.018). However, the NIKTBUT did not show significant variance between the two groups (glaucoma group: 10.19 ± 0.85 seconds; control group: 10.96 ± 1.37 seconds; p = 0.499). Conclusions Our study revealed a significant prevalence of OSD in our sample, with the OSDI questionnaire showing limited specificity. The notable increase in bulbar redness pointed to an elevated prevalence of OSD among glaucoma patients, emphasizing the considerable impact of preservatives on ocular surface damage. Recognizing the potential damage to the tear film and ocular surface is crucial for glaucoma experts, who must employ comprehensive therapeutic strategies to mitigate symptoms, advocating for the preferential use of preservative-free medications, when possible, for optimizing long-term treatment.