Purpose: To analyse the epithelial features of the bulbar conjunctiva in hyperbaric and low-tension glaucoma (LTG) using in vivo confocal microscopy (IVCM). Methods: Thirty-six eyes of 36 patients [18 affected by primary open-angle glaucoma (POAG) and 18 with LTG] were studied; control group was constituted by 28 eyes of 28 healthy subjects. All eyes were examined using digital confocal laser-scanning microscopy (HRT II Rostock Cornea Module). The main IVCM outcome measurements were mean density (MMD: cysts/mm(2) ) and mean total area (MMA: μm(2) ) of the epithelial microcysts. Results: The mean intraocular pressure level (mmHg ± SD) was 15.1 ± 1.7, 16.3 ± 3.1 and 12.6 ± 1.8 in healthy, POAG and LTG eyes, respectively. Conjunctival microcysts were found in all patients and subjects: for healthy subjects, MMD = 10.9 ± 11.1 cysts/mm(2) and MMA = 1501.9 ± 1191.1 μm(2) ; for patients infected with POAG, MMD = 36.8 ± 28.6 cysts/mm(2) and MMA = 7904.8 ± 7050.5 μm(2) ; and for patients infected with LTG MMD = 45.6 ± 29.0 cysts/mm(2) and MMA =7946.9± 5227.5 μm(2) . MMD and MMA were not significantly different between patients infected with POAG and those with LTG, whereas they were significantly greater in patients (fourfold and fivefold, respectively) than healthy subjects. Conclusions: The present study demonstrated that conjunctival microcysts represent an in vivo feature in all eyes with medically controlled POAG and LTG. Therefore, conjunctiva deserves careful analysis, because its accurate microscopic definition could help clarify the pathophysiology of aqueous outflow in glaucoma.