Glaucoma is one of the leading causes of blindness worldwide. Various randomized controlled clinical trials have shown that lowering intraocular pressure (IOP) does reduce the progression of primary open-angle glaucoma.
However, there is a lot of interest in nonpharmacological options that include lifestyle adjustment and alternative and complementary therapy (ACT). At least 5% of the glaucoma population uses ACT. Various lifestyle activities like exercise and alcohol can reduce IOP by 1 to 2 mm Hg but would have a small effect on glaucoma.
The psychological stress can increase IOP. Hypothetically and few studies do show neuroprotective effect (or effect on ocular blood flow) of alcohol, Gingko Biloba, bilberry, but the current evidence is weak for its routine use.
We must also remember the side effects of ‘medications’ (e.g., marijuana, alcohol) before promoting them as a remedy for glaucoma. In the current armamentarium of glaucoma management, ACT cannot substitute the conventional treatment available to lower IOP.
Most patients with glaucoma respond to some degree to medical, laser, or surgical therapies designed to lower intraocular pressure (IOP). However, some patients do not respond to those treatments or prefer additional routes to lower IOP or protect their optic nerves.
Although the only proven therapies are those that lower IOP and include medications, lasers, and surgeries, patients frequently inquire about other options.
Among these are marijuana, Ginkgo Biloba, memantine, acupuncture, meditation, blood pressure modification, and certain supplements as possible therapeutic candidates, explained Shan C. Lin, MD, co-director of research at the Glaucoma Center of San Francisco, California. MARIJUANA, which is legal for use in California, does lower IOP, but the duration of the effect is very short— about 3 hours—which would require the patient to use the drug almost continuously.
Potential downsides include concomitant lowering of the ocular perfusion pressure (by lowering the blood pressure) and addiction. The American Academy of Ophthalmology does not recommend marijuana as a primary treatment for glaucoma, Lin noted.
“There are better treatments to lower eye pressure, and it is not something that I recommend to my patients,” Lin continued. GINKGO was described by Lin as a “relatively interesting agent” for treating glaucoma and other diseases.
It is an herbal supplement obtained from the leaves of the Ginkgo Biloba tree and has been used in Chinese medicine for 5000 years. The compounds in the herb include flavonoids, lactones, and cyanidins, all antioxidants.
“While it has not been completely established exactly how these molecules work, they may be helpful in the treatment of Alzheimer’s disease, stroke, and possibly glaucoma,” he said. In addition to
antioxidant activity, ginkgo also preserves the mitochondria, inhibits apoptosis, and possibly increases blood flow.
In a study supporting the use of ginkgo, patients with glaucoma who had a significantly affected pretreatment mean deviation were treated with ginkgo for 4 weeks.
Investigators observed improved visual fields with a substantial decrease in the amount of mean deviation. The results of a retrospective study of ginkgo for normal-tension glaucoma found that the herb may stop the progression of the disease.
However, as many other studies do not support the herb’s positive effects, the jury is still out on the matter. A significant downside is the risk of bleeding in elderly patients, according to Lin.
MEMANTINE seemed to be a promising option at one point and was studied in a large clinical trial for 5 years. However, neither of the doses that were given was superior to the placebo in preventing progression.
According to Lin, memantine works to prevent apoptosis by blocking the calcium channels in the retinal ganglion cells. “Calcium influx into the retinal ganglion cells starts the apoptotic cascade; memantine starts early in the cascade to prevent cell damage and death,” Lin explained.
Memantine is approved in the United States and Europe to treat dementia, but it can cause some neurologic side effects. It is the hope of ophthalmologists that memantine would be the first neuroprotective drug that never came to fruition, but Lin remains optimistic that such a drug will be developed in the not-too-distant future.
ACUPUNCTURE has been attempted to treat glaucoma, but specialists have seen no overall effects regarding lowering of IOP, visual fields, or nerve scans in a recent University of California, Los Angeles study.
There have been slight increases in the IOP after the acupuncture sessions. The blood pressure was lower in the non–eye-related treatment group; however, lower blood pressure for patients with glaucoma may be harmful to their optic nerve perfusion.
MEDITATION in patients with glaucoma who were randomized to this activity was found to lower IOP by about 4 mm Hg compared with a control group in a study by an Indian group.
Although positive effects were seen in IOP and specific chemical mediators in the body, a drawback is that patients are reluctant to undertake meditation, Lin noted. PERFUSION PRESSURE, in other words, the difference between blood pressure and IOP, is also a factor for consideration when treating glaucoma.
Interestingly, Lin pointed out, lower blood pressure is detrimental for patients with glaucoma. “This is the new paradigm,” he said and cited the results of the Barbados Eye Study, in which lower blood pressure was associated with lower ocular perfusion pressure, as well as the Early Manifest Glaucoma Trial (NCT00000132), which found that glaucoma progression was associated with lower ocular perfusion pressure.
Lin said he asks his patients about the status of their blood pressure and often coordinates his treatment with primary care doctors if there is pathologically low blood pressure. Another impactful finding is that taking blood pressure medications at night, as many patients do, results in lower stroke and heart disease risk, but that is less than beneficial for the perfusion pressure as blood pressure is typically lower at night already.
Patients with physiologically low blood pressure may be advised to increase their salt intake, although this is controversial. Other available supplements that patients can consider to possibly counteract progressive glaucoma are blackcurrant, Mirtogenol (a combination of bilberry and pine bark extracts), palmitoylethanolamide, and omega 3 fatty acids.
Small studies have shown that they may lower IOP, increase ocular blood flow, or be neuroprotective. Generally, the go-to treatments for glaucoma remain drops, laser, and surgeries. “However, for patients whose glaucoma is progressing, these other agents, such as supplements and meditation, may have potential value,” Lin concluded.