In vivo confocal microscopy of conjunctiva in preservative-free timolol 0.1% gel formulation therapy for glaucoma

Purpose To evaluate the effects at 1year of preservative-free timolol gel and preserved timolol eye drops on conjunctiva and tear parameters. Methods Forty patients with primary open-angle glaucoma or ocular hypertension were randomized to the two treatment groups and compared with 20 healthy age-matched controls. Clinical tests (IOP, Schirmer I test, and lacrimal film break-up time BUT) and in vivo conjunctival confocal microscopy (IVCM) were performed in all patients at baseline and after 12months. IVCM (HRT II Rostock Cornea Module; Heidelberg Engineering GmbH, Heidelberg, Germany) was performed after topical anaesthesia in the four cardinal locations and at the corresponding limbus to analyse conjunctiva cells. The main IVCM outcomes were goblet cell density and epithelial regularity. Results IVCM and clinical parameters were similar in the three groups at baseline. After 12months, intra-epithelial goblet cell density was significantly lower in the preserved (48.25 +/- 7.70) than in the preservative-free beta-blocker group (86.83 +/- 22.17, p<0.001) and controls (88.9 +/- 18.33, p<0.001). The epithelial layer was significantly more regular in the preserved beta-blocker medication group than in the preservative-free beta-blocker group (p<0.001) and the control group (p<0.001). A significant reduction in both Schirmer I and BUT was found in the group of preserved timolol (respectively, 11.3 +/- 2.97 and 8.12 +/- 0.99) compared with preservative-free timolol (16.8 +/- 1.83 and 11.27 +/- 1.27, p<0.001) and controls (17.8 +/- 1.87 and 12.10 +/- 1.28, p<0.001). Conclusions Based on our IVCM data, preservative-free beta-blocker gel induces less changes at ocular surface than preserved beta-blockers, a fact that should be considered to obtain less adverse effects and maximal adherence to treatment in a chronic condition such as glaucoma.