Ginkgo biloba extract as a retinal protective agent: a systematic review of preclinical experiments

Ginkgo biloba extract (EGb), a complementary and alternative medicinal option, has gained extensive application in addressing conditions like cerebrovascular and peripheral vascular disorders. We aim to assess the neuroprotective efficacy of EGb for retinal disorders and to clarify its potential mechanisms of action through a systematic review. We searched original literature about laboratory experiments from four databases which were released until April 2024. The methodological quality of included in vivo studies was assessed using the SYRCLE risk of bias tool. The results showed that out of the 398 studies initially collected, 26 articles met the requirements for full-text review. 20 of them presented in vivo data, 2 detailed both in vitro and in vivo evidence, and 4 were in vitro experiments. Results demonstrated the protective effects of EGb against several retinal disorders, including retinal ganglion cell injury, retinal degeneration, ischemia, vitreo- or pre-retinal proliferative disorder, uveitis, and diabetic retinopathy. Based on SYRCLE's evaluation of bias risk, the in vivo studies' quality scores varied from 4 to 7 points. The data indicated that EGb preserved visual function by maintaining retinal morphology and structure in preclinical models. Its action mechanism may be associated with suppressing apoptosis, attenuating oxidative stress, reducing inflammation, inhibiting angiogenesis, and suppressing proteolysis. These preclinical findings suggest that EGb may be a promising neuroprotective agent for retinal disorders. However, the methodological limitations of the included studies necessitate cautious interpretation; to demonstrate the effectiveness and safety of EGb, more extensive clinical randomized controlled trials are required.