The use of medicinal plants in common ophthalmic disorders: A systematic review with meta-analysis

Abstract

Purpose: This study aimed to assess and compile the available research articles about medicinal plants used for ocular diseases.

Principal results: A total of 2949 articles were retrieved, 35 full-text articles were assessed for eligibility, and seven studies (4 observational and three experimental) with low to moderate quality were eligible and involved in the systematic review, with a total of 600 plants from 4 countries. Among the 600 plants, only 24 (4%) were used to assess the status. Both the fixed and random models of the studies showed that the included studies tended to predict the results for the observational studies (OR = 0.062, CI = 0.043-0.090 OR = 0.039, CI = 0.012-0.122) for different plants used for ocular diseases. High heterogeneity (estimated as I² = 87.078, Tau² = 1.161 and Q-value = 23.217 with a p-value of 0.000), while for experimental studies (I² = 94.928, Tau² = 23.211 and Q-value = 39.434 with a p-value of 0.000) and publication bias were reported.

Conclusion: Few articles representing approximately 600 plants of low to moderate quality reported using medicinal plants for ocular diseases. The meta-analysis confirmed the systematic review findings regarding the plants' traditional use with high heterogeneity and publication bias. A considerable gap was proven in the use of medicinal plants in ocular diseases requiring intensive research.

Keywords: Forest plot; Funnel plot; Medicinal plants; Meta-analysis; Ophthalmic; Prisma chart; Systematic review.

Graphical Abstract

Fig. 1

Prisma Flow chart results of inclusion/exclusion of the individual studies.

Fig. 2

The forest plot of 4 observational studies (A) represents their effect size on medicinal plants used for different eye disorders. For each study, the odds ratio and it's 95% CI was plotted with a blue square and horizontal line using both fixed and random-effect models, while OR = 1; no prediction, OR > or <1; prediction regardless the direction. whilst the 3 experimental studies (B) as plants use outcome. For each study, the standardized mean difference and its 95% CI of 4 repeated measures were plotted with circles anda horizontal line using both fixed- and random-effect models. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

The relative weights and residuals of the (A) Observational and (B) Experimental studies extracted from forest plots of the Medicinal plants used for different ocular disorders using both fixed and random-effect meta-analysis models.

Fig. 4

The funnel plot of 4 observational studies (A) and 3 Experimental studies (B), represents the publication bias of all studies. The graph plotted the standard error versus the log of either odds ratio or the Hedge's g, the diamonds shape illustrates the summary of the observed (blue) and imputed (red) hazard ratio of all studies. Each small blue circle indicates an individual study. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)