Different concentrations of hyaluronic acid eye drops for dry eye syndrome: a systematic review and Meta-analysis.

Aim: To compare high or low concentration of hyaluronic acid eye drops (HY) for dry eye syndromes (DES).

Methods: Randomized controlled trials (RCTs) comparing various concentrations of HY were searched in PubMed, Embase, Web of Science, Cochrane, SinoMed, CNKI, Wanfang Database, CQVIP, and Chinese journals databases between inception and July 2023. Pooled standardized mean differences (SMD) or weighted mean difference (WMD) with 95% confidence intervals (CI) from RCTs evaluating Schirmer's I test (SIT), corneal fluorescein staining score (CFS), tear breakup time (TBUT), DES score (DESS), and Ocular Surface Disease Index (OSDI) were calculated. Sensitivity analysis, Egger's test and Meta-regression analysis were performed for all indicators.

Results: We conducted a Meta-analysis of 10 RCTs that met the inclusion criteria, involving 1796 cases. High-concentrations group significantly improved the outcome of CFS according to random effects modelling (SMD, -3.37; 95%CI, -5.25 to -1.48; =0.0005). The rest of the results were not statistically significant, including indicators such as SIT, TBUT, DESS and OSDI.

Conclusion: For dry eyes with positive corneal staining, a high concentration of HY is recommended, whereas in other cases, a high concentration of HY does not offer a more pronounced advantage over a low concentration of HY in the treatment of dry eyes.