Efficacy of Hyaluronic Acid Eye Drops in the Treatment of Dry Eye Syndrome – Results of a Meta-Analysis
Dry eye syndrome affects 5–30% of individuals over the age of 50. The beneficial effect of hyaluronic acid on the symptoms of this condition has been well described in both preclinical and clinical studies, and it has been shown that its topical application increases the secretion of water and mucin on the surface of the eye. The meta-analysis presented below focused on the efficacy of eye drops containing hyaluronic acid in the treatment of dry eye syndrome.
Evaluated Studies and Population
A total of 17 randomized controlled trials published between 1998 and 2018 were included in the meta-analysis from the databases Pubmed, EMBASE, Cochrane, DBpia, KoreaMed, KMBASE, RISS, and KISS. A total of 1339 patients (mean age 50–60 years, predominantly female) with dry eye syndrome were treated with eye drops containing hyaluronic acid (HA; n = 627) or without it (n = 712). In 6 studies, eye drops with 0.1% HA were used, and in 11 studies, HA concentrations of 0.15–0.4% were used. In the second group, other lubricants were used instead of HA – carboxymethylcellulose in 6 studies, various emulsions, polyvinyl alcohol, or carbomer in 6 studies, and in the remaining 5 studies, the control preparation was saline solution.
Patients were monitored for a period of 14–90 days of using eye drops. The primary monitored parameters were standardized mean difference (SMD) of Schirmer test score, assessment of tear film stability (TBUT – tear break-up time), corneal staining with fluorescein (Oxford scale), and a questionnaire for subjective evaluation of eye irritation and impact on visual acuity (OSDI – ocular surface disease index).
Studies with patients who had undergone eye surgery (including cataracts) and those who previously used therapeutic eye drops (e.g., diagnosed with glaucoma) or contact lenses were excluded from the meta-analysis.
Findings
According to the Schirmer test, eye drops with HA significantly improved tear production compared to drops without HA (SMD 0.18; 95% confidence interval [CI] 0.03–0.33). Similar tear film stability was observed in both groups (TBUT; SMD -0.00; 95% CI -0.10 to 0.11). Subgroup analysis subsequently showed a significant improvement in TBUT score for drops with HA compared to drops containing only saline solution (SMD 0.28; 95% CI 0.03–0.52).
The corneal fluorescein staining score, indicating epithelial integrity, was comparable in the group of patients using eye drops containing HA and those with other lubricants (SMD -0.01; 95% CI -0.17 to 0.16). The OSDI score was numerically lower in the group of patients using eye drops with HA, but the difference was not statistically significant (SMD -0.14; 95% CI -0.30 to 0.02).
Conclusion
Hyaluronic acid eye drops in patients with dry eye syndrome significantly increase tear production compared to eye drops without HA. However, further clinical studies are needed to assess the efficacy based on patient age, severity of dry eye syndrome, treatment duration, and dosage.
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Source: Yang Y.-J., Lee W.-Y., Kim Y.-J., Hong Y.-P. A meta-analysis of the efficacy of hyaluronic acid eye drops for the treatment of dry eye syndrome. Int J Environ Res Public Health 2021; 18 (5): 2383, doi: 10.3390/ijerph18052383.
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