The Ocular Surface in Medically Controlled Glaucoma: An In Vivo Confocal Study

PURPOSE To study clinical and in vivo laser scanning confocal microscopy (LSCM) ocular surface findings in stable, medically controlled primary open-angle glaucoma (MCPOAG) patients. METHODS We recruited 100 consecutive patients with MCPOAG and 50 healthy controls. Patients had to have been treated with the same medical regimen without variation for the 18 months before enrollment and were excluded if there was a history of dry eye prior to glaucoma diagnosis. Each participant underwent ocular surface clinical and LSCM examination. RESULTS In MCPOAG patients, subbasal nerve length and tortuosity and dendritic cell density were increased compared to controls (P < 0.01), but there were no clinical abnormalities. Patients treated with preserved drugs (n = 80) had reduced tear film breakup time (P < 0.05, ANOVA), and those preserved with benzalkonium chloride (n = 72) had reduced Schirmer test values (P < 0.001). Patients (n = 50) treated with two or more drugs had increased lissamine green conjunctival staining (P < 0.001, LSD post hoc test). Patients (n = 29) treated with three or more eye drops daily had decreased Schirmer test values. Laser scanning confocal microscopy showed subbasal changes related to preservatives, type and number of drugs, and number of eye drops. CONCLUSIONS In stable MCPOAG patients without dry eye history, the ocular surface changes due to antiglaucoma medications are mostly subclinical. Active ingredients, preservatives, number of concomitant drugs, and number of eye drops instilled per day are all elements that can induce ocular surface changes. The clinical relevance of these changes remains to be determined.