Objective ocular surface tolerance in patients with glaucoma treated with topical preserved or unpreserved prostaglandin analogues.

Purpose: Preservatives in glaucoma medications have been associated with ocular toxicity. We compared ocular signs and symptoms in patients with open-angle glaucoma or ocular hypertension treated in monotherapy with preserved or preservative-free prostaglandin analogues.
Methods: Observational cross-sectional clinical study in real life. 82 patients treated for at least 6 months with prostaglandin analogue were assessed for intraocular pressure, ocular symptoms and ocular signs including conjunctival hyperaemia, tear break-up time and tear meniscus height measured using objective and non-invasive methods (OCULUS Keratograph 5M). Patients presenting with symptoms of ocular toxicity with preserved prostaglandin analogues were switched to preservative-free latanoprost, and a second assessment was processed 6 months after.
Results: At inclusion, 30 (36.6%) patients were treated with preservative-free latanoprost, 25 (30.5%) with preserved latanoprost, 16 (19.5%) with preserved travoprost and 11 (13.4%) with preserved bimatoprost. Patients treated with preservative-free latanoprost reported significantly less ocular symptoms upon instillation (mainly burning) and between instillations than patients treated with preserved prostaglandin analogues. The mean conjunctival hyperaemia (limbal + bulbar) was significantly lower with preservative-free latanoprost (2.08 ± 0.55) compared to preserved latanoprost (2.50 ± 0.7, p = 0.0085), preserved travoprost (2.67 ± 0.82, p = 0.0083) and preserved bimatoprost (2.68 ± 0.67, p = 0.0041). There were no relevant between-group differences in mean tear meniscus height and break-up time. Ocular symptoms and conjunctival hyperaemia improved when preserved prostaglandin analogues were switched to preservative-free latanoprost for 6 months while intraocular pressure reduction was maintained.
Conclusion: Overall, this study suggests a better subjective and objective ocular tolerance when patients were treated with preservative-free latanoprost than with other preserved prostaglandin analogues monotherapy. Switching to preservative-free latanoprost maintained intraocular pressure at the same level as preservative prostaglandin analogue, but improved ocular surface tolerance.