Introduction
The primary therapeutic approach to glaucoma involves the long-term use of intraocular pressure (IOP)-lowering eyedrops. However, the prevalent use of benzalkonium chloride (BAK) as a preservative in glaucoma eyedrops has been associated with ocular side effects, prompting a demand for alternatively preserved (AP) or preservative-free (PF) eyedrops. Studies comparing various preservatives have shown conflicting evidence concerning the safety of BAK-preserved (BP) eyedrops, some studies indicating no notable concerns and others reporting adverse effects. The current protocol concerns a network meta-analysis enabling systematic investigation of the IOP-lowering efficacy and safety profiles of BP, AP and PF eyedrops in patients with glaucoma for whom randomised controlled trials (RCTs) are available.
Methods and analysis
This study will evaluate the IOP-lowering effects of glaucoma eyedrops, comparing formulations with and without preservatives in patients with glaucoma. A systematic search for RCTs, regardless of language or publication date, will be conducted across three electronic databases (Cochrane search engine, Embase and MEDLINE) from 1 March 2024. Two reviewers will conduct a sequential screening of titles and abstracts, followed by full-text papers, to extract useful data. The two reviewers will also assess the internal validity of studies using the relevant and domain-based risk of bias assessment tool. Overall evidence quality will be assessed using the Confidence in Network Meta-Analysis approach and presented in summarised form with network diagrams. Forest plots will be generated for enhanced visualisation of the included glaucoma eyedrops’ effects, and pairwise effect sizes will be calculated based on available evidence in the network.
Ethics and dissemination
No ethics review or approval is required for this work, as it will synthesise evidence obtained from published studies. A paper presenting the findings will be submitted to a peer-reviewed journal for publication.
PROSPERO registration number
CRD42024498328