Ginkgo Biloba and Ocular Blood Flow in Primary Open-angle Glaucoma
Condition: Glaucoma, Open-Angle
MeSH terms: Glaucoma; Glaucoma, Open-Angle
Study type: Interventional
Phase: Phase 2

Summary: 
      Glaucoma is one of the leading causes of blindness. Ginkgo biloba may be part of an effective
      treatment strategy for glaucoma because it has been shown to improve blood flow, it has
      antioxidant properties, it can relax smooth muscle, and it can protect neurons from damage.
      The goal of our study was to determine whether Ginkgo biloba would result in increased ocular
      blood flow which may protect against glaucoma damage.
    

Detailed description: 
      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.
    

Intervention name(s): Ginkgo biloba; Placebo to Ginkgo biloba
Intervention type(s): Drug; Drug
Intervention description(s): 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.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: ocular blood flow; ginkgo biloba; glaucoma; vasospasm