Does Ginkgo Biloba Help Treated Glaucoma Patients?

Summary

A new 2025 clinical study tested whether Ginkgo biloba extract (GBE) could improve blood flow in the eyes of people with treated early-to-moderate primary open-angle glaucoma. Unlike some earlier studies that suggested Ginkgo might improve ocular circulation, this study found no clinically meaningful improvement in blood-vessel density after four months of supplementation.

Researchers used optical coherence tomography angiography (OCT-A), a noninvasive imaging technique that can measure tiny blood vessels in the retina and around the optic nerve. After four months, the Ginkgo group showed no significant improvement in perfusion density in the macula, and peripapillary perfusion density actually decreased slightly. The authors emphasized that the decrease was small and could have been due to chance.

Key Takeaways

• Researchers studied whether Ginkgo biloba extract could improve blood-vessel density in the eyes of patients with treated early-to-moderate primary open-angle glaucoma.
• The study included 17 glaucoma patients who took 120 mg of Ginkgo biloba extract twice daily for four months, along with 17 matched glaucoma controls who did not receive Ginkgo.
• Researchers used optical coherence tomography angiography (OCT-A) to measure blood-vessel density in the macula and around the optic nerve.
• Ginkgo did not significantly improve perfusion density in the macula after four months.
• Peripapillary perfusion density decreased slightly in the Ginkgo group rather than increasing.
• The study found no significant difference between the Ginkgo and control groups at the four-month follow-up.
• No adverse events were reported, and participants in the Ginkgo group did not report missed doses or early discontinuation.
• The researchers concluded that more studies are needed before Ginkgo biloba supplementation can be recommended for glaucoma.

Why Is This Study Important?

Glaucoma is a progressive disease that damages the optic nerve and can cause permanent vision loss. Lowering intraocular pressure (IOP) remains the only modifiable risk factor known to cause retinal ganglion cell damage and visual field loss, and current glaucoma treatment is centered on lowering eye pressure.

At the same time, researchers continue to investigate whether changes in blood flow and vascular regulation also contribute to glaucoma. This question has been especially important because earlier studies of Ginkgo biloba reported potentially beneficial effects on ocular circulation and, in some patients with normal-tension glaucoma, on visual-field progression.

The Hodgson study is important because it tested this idea using OCT-A in a different group of patients: people with treated early-to-moderate primary open-angle glaucoma who had previously had elevated eye pressure.

What Is Ginkgo Biloba?

Ginkgo biloba is a tree species that has been used in traditional medicine for centuries. Modern research commonly uses a standardized Ginkgo biloba extract called EGb 761, which contains flavonoid glycosides and terpene lactones and has most of the toxic ginkgolic acid removed.

Ginkgo has attracted interest in glaucoma because of proposed effects on the vascular system and because laboratory and clinical studies have explored possible antioxidant and neuroprotective effects.

Researchers have investigated whether Ginkgo might:

• Support circulation in small blood vessels
• Influence vascular function
• Help protect nerve cells from oxidative stress
• Potentially support retinal ganglion-cell survival

However, these proposed effects do not mean that Ginkgo has been proven to prevent glaucoma progression or preserve vision. The 2025 Hodgson study was designed to test one specific question: whether Ginkgo supplementation changes measurable ocular perfusion.

Study Design

Type of Study

The investigators conducted a:

• Prospective interventional pilot study
• Four-month supplementation study
• Matched-control study

Importantly, the study was not randomized. Seventeen patients received Ginkgo, and each was matched with a control patient from an existing research database based on age, sex, and glaucoma severity.

Who Participated?

The study included:

• 17 patients with early-to-moderate primary open-angle glaucoma who received Ginkgo biloba extract
• 17 matched glaucoma control patients
• Adults with glaucoma that had already been treated with medication, selective laser trabeculoplasty (SLT), or both

The average age was about 67 years in both groups. The glaucoma group receiving Ginkgo had a mean visual-field mean deviation of 3.45 dB, compared with 4.21 dB in the control group.

How Much Ginkgo Did Participants Take?

Participants in the Ginkgo group were instructed to take 120 mg of Ginkgo biloba extract twice a day for four months, for a total of 240 mg per day. The supplement used in the study was a commercially available product approved in Canada.

How Did Researchers Measure Blood Flow?

Optical Coherence Tomography Angiography (OCT-A)

The primary measurements came from optical coherence tomography angiography, or OCT-A. OCT-A is a noninvasive imaging technology that can visualize and quantify blood flow in the tiny vessels of the retina.

Researchers obtained scans centered on the macula and the optic nerve. They then calculated perfusion density, which represents the proportion of an image occupied by areas showing blood flow.

What Did Researchers Measure?

The study focused on two main areas:

• Macular perfusion density — blood-vessel density in the central retina
• Peripapillary perfusion density — blood-vessel density in the retinal region surrounding the optic nerve

Researchers also examined retinal nerve fiber layer (RNFL) thickness as a measure related to glaucoma progression.

Results

No Improvement in Macular Perfusion

After four months of Ginkgo supplementation, macular perfusion density did not improve significantly. The average value changed from 0.32 at baseline to 0.30 at follow-up, with a p value of 0.17.

For comparison, the control group changed from 0.29 to 0.30, also without a statistically significant difference.

Peripapillary Perfusion Decreased Slightly

The more unexpected finding involved the area surrounding the optic nerve. Peripapillary perfusion density in the Ginkgo group decreased from 0.44 to 0.42, a statistically significant change with a p value of 0.02.

However, the authors did not interpret this as evidence that Ginkgo harms the optic nerve. The decrease was small, the control group showed a small change in the same direction, and OCT-A measurements can vary between visits. The researchers therefore said the finding could have been due to chance.

Ginkgo Did Not Outperform the Control Group

When researchers directly compared the Ginkgo and control groups, there was no significant difference in perfusion density at the four-month follow-up in either the macula or the peripapillary region.

This is an important distinction. A change within one group can sometimes appear statistically significant without demonstrating that the treatment itself produced a meaningful benefit. In this study, the between-group comparisons did not show a clear advantage for Ginkgo.

No Significant Change in Retinal Nerve Fiber Layer Thickness

The researchers also looked at OCT measurements of retinal nerve fiber layer thickness. There was no significant change over the study period in either the Ginkgo group or the control group, and the change did not differ significantly between groups.

Why Didn't Ginkgo Improve Blood Flow?

The study cannot tell us exactly why Ginkgo failed to increase measured ocular perfusion. The authors offered several possible explanations, including the possibility that Ginkgo simply does not improve perfusion density in this patient population or that OCT-A may not be sensitive enough to detect the effect of Ginkgo.

The type of glaucoma may also matter. Earlier studies that reported positive findings often involved healthy young adults or patients with normal-tension glaucoma. The Hodgson study instead enrolled older patients with primary open-angle glaucoma who had previously experienced elevated eye pressure and were already receiving treatment.

The authors noted that vascular factors may be more relevant in some patients with lower eye pressure, although the overall role of vascular dysregulation in glaucoma remains controversial.

Why These Findings Matter

The 2025 study adds an important counterpoint to earlier research suggesting that Ginkgo biloba may improve ocular circulation. It shows that promising findings from one patient population or one measurement technique do not necessarily translate to another group of glaucoma patients.

The study also highlights the difference between a biological hypothesis and a proven treatment. Ginkgo may have vascular or neuroprotective properties, but this study did not demonstrate that supplementation improves ocular perfusion or slows glaucoma progression.

Earlier research has reported potentially favorable results. For example, studies cited by Hodgson and colleagues reported less visual-field progression in patients with normal-tension glaucoma and improvements in visual-field mean deviation in another normal-tension glaucoma population. The 2025 findings suggest that those results should not automatically be generalized to patients with treated primary open-angle glaucoma.

Study Limitations

Small Sample Size

Only 17 patients received Ginkgo. A study this small may not be able to detect modest treatment effects reliably, and the findings need confirmation in larger clinical trials.

The Study Was Not Randomized

The Ginkgo group was compared with matched controls from an existing research database rather than patients being randomly assigned to treatment. This limits the strength of conclusions about cause and effect.

Different Glaucoma Medications

Participants were using different glaucoma treatments, including prostaglandin analogues, beta blockers, and carbonic anhydrase inhibitors. Some medications can affect vascular function and could potentially influence the measured effect of Ginkgo.

Short Follow-Up

The study followed participants for four months. Although the authors considered four months an appropriate period for observing possible blood-flow changes, this is still too short to determine whether Ginkgo affects long-term glaucoma progression or vision loss.

Blood-Vessel Density Is Not the Same as Vision

Most importantly, the study measured perfusion density rather than directly demonstrating preservation or improvement of vision. Even if a treatment changes a blood-flow measurement, that does not necessarily mean it will slow optic-nerve damage or prevent visual-field loss.

The Bottom Line

A 2025 pilot study by Hodgson and colleagues found that four months of Ginkgo biloba extract supplementation did not significantly improve blood-vessel density in the macula or around the optic nerve in patients with treated early-to-moderate primary open-angle glaucoma.

The study actually found a small decrease in peripapillary perfusion density in the Ginkgo group, but the authors cautioned that this difference was small and could have resulted from chance or measurement variability. There was also no significant advantage for Ginkgo when the treatment group was compared directly with matched controls.

These results do not prove that Ginkgo biloba has no neuroprotective effects. Instead, they show that this particular four-month regimen did not produce a measurable improvement in OCT-A perfusion density in this patient population. Larger and better-controlled studies are needed before Ginkgo supplementation can be recommended as a treatment for glaucoma.

Study Reference

Hodgson K, Palakkamanil MM, Zhang A, Dyachok OM, Smith CA, Nicolela MT, Chauhan BC, Shuba LM. Effect of ginkgo biloba extract on macula and peripapillary perfusion examined using optical coherence tomography angiography. Canadian Journal of Ophthalmology. 2025;60(4):e566-e571. doi:10.1016/j.jcjo.2025.01.015.