Ginkgo Biloba and Ocular Blood Flow in Primary Open-angle Glaucoma
|ClinicalTrials.gov Identifier: NCT02376114|
Recruitment Status : Completed
First Posted : March 3, 2015
Last Update Posted : March 3, 2015
|Condition or disease||Intervention/treatment||Phase|
|Glaucoma, Open-Angle||Drug: Ginkgo biloba Drug: Placebo to Ginkgo biloba||Phase 2|
Glaucoma is one of the leading causes of blindness. Glaucoma progression sometimes occurs despite apparent control of intraocular pressure. Therefore, there may be other factors involved in glaucoma progression in some patients. Evidence is mounting that glaucoma patients are more likely to have abnormal ocular blood flow and vasospasm compared to those without glaucoma. Also, a study showed that those with progressive glaucoma had decreased blood flow compared to those with stable glaucoma or healthy controls. Endothelin-1, a potent vasoconstrictor, may be involved in these blood flow abnormalities. If the dysregulation of blood flow is causally related to the progression of glaucoma, then therapies aimed at improving the regulation of blood flow may help to prevent this progression.
Ginkgo may be part of an effective treatment strategy for glaucoma because it has been shown to improve peripheral and cerebral blood flow. Other properties of Ginkgo that may aid in the treatment of glaucoma include antioxidant properties, inhibition of platelet activating factor, relaxation of smooth muscle, and neuroprotective properties. Ginkgo may be particularly useful in relaxing vasospasm. Two controlled trials have examined the effect of Ginkgo on ocular blood flow in healthy subjects. One randomized crossover trial found that 2 days of Ginkgo increased the end diastolic velocity in the ophthalmic artery compared to placebo. However, another trial found that 1 dose of Ginkgo had no significant effects on ocular blood flow parameters. In people with normal tension glaucoma, Park et al found that 4 weeks of Ginkgo increased peripapillary retinal blood flow. Two randomized controlled trials have examined the impact of Ginkgo biloba on visual field in people with normal tension glaucoma with conflicting results. Clearly, there is a need for more research on this topic.
The goal of our study was to determine whether Ginkgo biloba would result in increased ocular blood flow, reduced vasospasm, and reduced endothelin-1 levels.
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||19 participants|
|Intervention Model:||Crossover Assignment|
|Masking:||Double (Participant, Outcomes Assessor)|
|Official Title:||The Effect of Ginkgo Biloba on Ocular Blood Flow in Primary Open-Angle Glaucoma Patients: A Double-Blind Randomized Crossover Trial|
|Study Start Date :||August 2011|
|Actual Primary Completion Date :||February 2014|
|Actual Study Completion Date :||February 2014|
Patients receive Ginkgo biloba and then placebo afterwards.
Drug: Ginkgo biloba
The Ginkgo biloba extract that was used contained 24% ginkgo flavone glycosides and 6% terpene lactones (Vitamin Research Products, Carson City, Nevada). Patients took 60 mg of Ginkgo or a placebo twice daily by mouth for two weeks. The placebo consisted of 40 mg of corn starch. Ginkgo and the placebo were encapsulated to ensure identical appearance.
Patients receive placebo and then Ginkgo biloba afterwards.
Drug: Placebo to Ginkgo biloba
- Change in optic nerve head blood flow in the rim region as measured with the Heidelberg Retinal Flowmeter [ Time Frame: 4 weeks and 10 weeks ]Change in optic nerve head blood flow in the rim region as measured with the Heidelberg Retinal Flowmeter
- Change in retinal blood flow as measured by the Canon Laser Blood Flowmeter [ Time Frame: 4 weeks and 10 weeks ]Change in retinal blood flow as measured by the Canon Laser Blood Flowmeter
- Change in ocular pulse amplitude as measured with the Pascal Dynamic Contour Tonometer [ Time Frame: 4 weeks and 10 weeks ]Change in ocular pulse amplitude as measured with the Pascal Dynamic Contour Tonometer
- Change in peripheral vasospasm as measured during the cold provocation test using the Transonic Laser Doppler Flowmeter [ Time Frame: 4 weeks and 10 weeks ]Change in peripheral vasospasm as measured during the cold provocation test as measured using the Transonic Laser Doppler Flowmeter
- Change in endothelin-1 levels as measured by an enzyme-linked immunosorbent assay kit [ Time Frame: 4 weeks and 10 weeks ]Change in endothelin-1 levels as measured by an enzyme-linked immunosorbent assay kit
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02376114
|Montreal, Quebec, Canada, H1T2M4|
|Principal Investigator:||Ellen Freeman, PhD||Maisonneuve-Rosemont Hospital|
|Principal Investigator:||Mark Lesk, MD||Maisonneuve-Rosemont Hospital|