Safety and efficacy of pilocarpine, cevimeline, and diquafosol compared to artificial tears for the treatment of dry eye: protocol for a systematic review

Abstract
Background: Dry eye disease (DED) is a condition that compromises the ocular surface and affects millions of people around the world. In recent years, a scheme has been proposed for the treatment of DED, with the use of artificial tear being the mainstay of treatment. In this scheme, the use of secretagogues is suggested as part of the treatment for patients with moderate to severe affectation. With this systematic review, we aim to evaluate the effectiveness and safety of secretagogues for DED. Methods: Electronic databases will be searched; we will include randomized controlled trials that compare secretagogues and artificial tears. Study inclusion will not be restricted on the basis of language or publication status. We will use Google Translate to assess studies written in languages other than English and Spanish. Identification, evaluation, data extraction, and assessment of risk of bias will be conducted by two authors of the review, a third review author will resolve any disagreement. The outcomes will be the ocular surface disease index score, tear film break-up time, Schirmer test score, VRQoL Score, and tear film osmolarity. We will use the Cochrane Collaboration Risk of Bias 2 (RoB 2) tool for assessing the risk of bias of the included studies. Based on the heterogeneity of the included studies, we will combine the findings in a meta-analysis using a fixed effect model if heterogeneity ≤ 50% or a random effect model if heterogeneity > 50%. If we deem meta-analysis as inappropriate, we will document the reasons and report findings from the individual studies narratively. Discussion: Based on the evidence obtained, we will evaluate the effect of pilocarpine, cevimeline, and diquafosol and compare it to artificial tears on multiple outcome measures. This systematic review aims to determine the efficacy and safety of the secretagogues pilocarpine, cevimeline, and diquafosol to help clinicians in the decision-making process. Trial registration: PROSPERO CRD42020218407.