Effects of Gingko biloba on Systemic and Retinal Blood Circulation

Abstract

Introduction: The use of alternative medicine has increased in recent years due to its minimal side effects and holistic approach to healthcare. Ginkgo biloba extract (GBE) is a natural antioxidant derived from leaves of the Maidenhair tree and is known to improve blood vessel health. However, its effect on the retinal circulation is not fully understood. The purpose of this study is to examine the effect of GBE oral supplements on the retinal circulation.

Methods: Blood pressure (Omron HEM-705CP), intraocular pressure (Canon T2 non-contact Tonometer), and blood flow velocities in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries (Color Doppler imaging, Sequoia) were obtained from participants aged 22 to 36 with good ocular and systemic health. Measurements were performed between 12-5pm to control for circadian rhythm effects at 3 study visits: 1 week before baseline at pre-supplement visit (T-1), at baseline (T0) and after 4 weeks of 240mg/day GBE supplementation at post-supplement visit (T4). Ocular perfusion pressure (OPP) was calculated as OPP = 2/3 * (Mean Arterial Pressure – IOP).

Results: Thirteen participants were recruited (5m, 8f; 25.54 ± 3.64 years). No significant changes in systemic blood pressure, OPP or retinal circulation were observed between pre-supplement visit (T-1) and baseline (T0) prior to GBE supplementation. However, the ophthalmic and short posterior ciliary arteries peak systolic velocities increased from baseline (T0) to post-treatment (T4) (ophthalmic artery baseline ave ± SD: 18.97 ± 6.67cm/s; post-treatment:24.33 ± 6.90cm/s; short posterior ciliary artery baseline: 10.56 ± 1.87cm/s; post-treatment: 11.58 ± 1.97cm/s; both p < 0.05). The increases in ophthalmic and short posterior ciliary arteries peak systolic velocities did not correlate with changes in systolic BP, diastolic BP, or OPP.

Discussion: Our preliminary data suggests that 240mg/day of Ginkgo biloba extract (GBE) may increase blood flow in two major retinal ocular arteries. Such increase appears independent from changes in systemic blood pressure or OPP.