Does CBD Work for Glaucoma?
- There have been conflicting reports on whether CBD might help treat glaucoma.
- A study conducted by researchers from Indiana University found that CBD interferes with the lowering of eye pressure, which is key to the effective treatment of glaucoma (1).
- Another study discovered that a dosage of 40 mg of CBD on glaucoma patients resulted in increased eye pressure, posing higher risk factors for the test subjects (2).
- The American Academy of Ophthalmology also discouraged the use of CBD products and other cannabis-related treatments for glaucoma (3).
- Until further research is done on CBD’s effects on glaucoma, its use as a treatment option is not recommended. Those with glaucoma are advised to consult with their ophthalmologists for alternative treatments.
CBD and Glaucoma
Glaucoma is an eye condition that damages optical nerves and could eventually result in blindness. However, no treatment has been discovered to cure patients of the condition completely.
Treatments like eye drops, oral medications, and surgeries can only delay the progression of glaucoma. Hence, some people have resorted to alternative medications; for instance, cannabis products like cannabidiol (CBD).
While CBD may help alleviate the symptoms of various ailments ranging from psychiatric conditions to heart diseases, the research on CBD and glaucoma, thus far, has conflicting reports.
There have been studies on the therapeutic effects of cannabinoids on glaucoma. Cannabinoids are substances that help regulate functions like mood, appetite, memory, pain reception, and immune system activities. They bind with receptors in the endocannabinoid system (ECS) to fulfill these functions.
These cannabinoids can come from the body, be produced in laboratories, or derived from the Cannabis Sativa plant.
CBD and tetrahydrocannabinol (THC) are the most notable phytocannabinoids that come from marijuana plants.
Some studies outline the therapeutic benefits of cannabinoids like CBD on glaucoma.
A study published in the journal The British Journal of Ophthalmology states that cannabinoids may help in the treatment of glaucoma (4). These cannabinoids seem to reduce intraocular pressure (IOP) and have neuroprotective effects.
Another study in 2016 reveals that manipulating the ECS may have therapeutic effects on eye health unrelated to glaucoma. The study says these manipulations might give retinal protection and help restore normal vision (5).
A study has also found that cannabinoids can reduce inflammation of the cornea and attenuate the cornea’s increased sensitivity to pain (6).
Full-Spectrum CBD Oil for Glaucoma
Patients who want to use CBD oil to treat their ailments have three types of CBD oils to choose from: full-spectrum, broad-spectrum, and CBD isolate.
Full-spectrum CBD oil uses all the components of a cannabis plant, namely trace amounts of THC, terpenes, fatty acids, flavonoids, and essential oils. This type of CBD oil is believed to be the most effective because it produces an entourage effect.
The entourage effect occurs because all the cannabis plant’s active ingredients synergize to produce maximum therapeutic benefits.
Researchers have found that THC is the active ingredient in Cannabis Sativa that helps relieve glaucoma symptoms. Because full-spectrum CBD only contains trace amounts of THC, it is not recommended for glaucoma treatment.
Glaucoma treatment involves lowering the eye pressure or the IOP. Studies show that CBD may worsen intraocular pressure.
A 2018 study published in the journal Investigative Ophthalmology and Visual Science featured researchers from Indiana University who administered two of the primary components of medical cannabis to mice (7). These were the psychoactive THC and CBD.
Alex Straiker and his co-authors have found that a single topical application of THC significantly lowered the test subjects’ IOP for eight hours. Meanwhile, the use of CBD with THC interferes with THC from lowering ocular pressure.
Another study done in 2006 and published in the Journal of Glaucoma found that upon administration of THC sublingually (under the tongue) to glaucoma patients, lower IOP was observed (8). Meanwhile, 20 mg of CBD did not lower eye pressure in the test subjects.
When 40 mg of CBD was administered to these patients, however, IOP increased significantly.
From the studies cited above, it can be concluded that full-spectrum CBD oil’s trace amounts of THC cannot help in the treatment of glaucoma.
Similarly, broad-spectrum CBD oil and CBD isolates are ineffective glaucoma treatments because these CBD oil types do not contain THC.
Broad-spectrum CBD oil contains all the ingredients of full-spectrum oils except for THC. CBD isolates, meanwhile, are made from pure CBD because they only contain isolated cannabidiol.
Despite these studies, ophthalmologists still do not recommend the use of THC. This ingredient causes psychoactive effects and may produce a high in its users. Drug tests can also detect THC levels in the body. It is also highly addictive.
Data from the American Academy of Ophthalmology (AAO) state that glaucoma treatment involves controlling eye pressure 24 hours a day (9).
AAO also says that reducing IOP requires 3 to 5 mm Hg. To maintain that reduction, a patient should ingest approximately 18 to 20 mg of THC six to eight times a day—a substantial amount of the psychoactive substance to consume.
The organization of ophthalmologists cautions against THC’s effects on mental clarity, mood, and the ability to engage in everyday activities. AAO also emphasized that marijuana use every three to four hours is not cost-effective.
What is Glaucoma?
AAO describes glaucoma as an eye disease that targets the eye’s optic nerve. It is characterized by a buildup of fluid in the front part of the eye, increasing eye pressure that can severely damage the optic nerve (10).
Glaucoma has many types, but the most common include primary open-angle glaucoma and angle-closure glaucoma.
Open-angle glaucoma occurs more commonly. Initially, it is not painful and does not affect vision.
The effects of this type of glaucoma are gradual, mainly characterized by the inability of the eyes to drain fluid properly. As the eye pressure increases, nerve damage also begins.
In some people, the risks of getting glaucoma are high. Their optic nerves are more sensitive to normal eye pressure.
So that the early signs of glaucoma are detected, it is encouraged that patients regularly consult with an eye doctor.
The other type of glaucoma, angle-closure, can lead to vision loss immediately when left untreated. This type of glaucoma is characterized by the iris being too close to an eye’s drainage angle.
In angle-closure glaucoma, the iris can block the drainage angle completely. Eye pressure also rises and may result in an acute angle-closure glaucoma attack.
Symptoms include (11):
- Severe headache
- Eye pain
- Nausea and vomiting
- Blurred vision
- Halos around lights (rainbow-colored rings)
- Eye redness
Similar to open-angle glaucoma, angle-closure glaucoma is difficult to detect early on. Usually, patients discover it only when they already have an attack.
Later symptoms of glaucoma include loss of peripheral vision (side vision) and blindness.
While the types of glaucomas mentioned earlier have unknown causes, secondary glaucoma, meanwhile, has identifiable causes (12).
Some secondary glaucoma causes include injury to the eye, incomplete development of the eye’s drainage canals before birth, among others.
How CBD Oil Works to Alleviate Symptoms of Glaucoma
CBD may still help in treating the symptoms of this eye condition despite its side effects on patients with glaucoma.
CBD for Migraines
A study in 2018 outlines the potential therapeutic effects of CBD in treating migraines because of its analgesic and anti-inflammatory properties (13).
CBD for Nausea
Reports published in the British Journal of Pharmacology have shown that CBD’s antiemetic properties can help alleviate symptoms of nausea and vomiting (14).
Clinical trials have revealed that the use of cannabis-related products like CBD may worsen glaucoma. While THC use temporarily relieves some glaucoma symptoms, ophthalmologists highly advise against the use of medical marijuana in treating the condition.
THC’s addictive properties could pose more risks than therapeutic benefits. Its effect in the body is also temporary and unsustainable in treating eye conditions like glaucoma.
Despite these, CBD still has promise for treating some symptoms that stem from glaucoma, such as nausea and migraines.
Until further research on CBD’s effect on glaucoma is made, it is best to consult an ophthalmologist for other treatment options.
- Miller, Sally et al. “Δ9-Tetrahydrocannabinol and Cannabidiol Differentially Regulate Intraocular Pressure.” Investigative ophthalmology & visual science vol. 59,15 (2018): 5904-5911. doi:10.1167/iovs.18-24838
- Tomida, Ileana et al. “Effect of sublingual application of cannabinoids on intraocular pressure: a pilot study.” Journal of glaucoma vol. 15,5 (2006): 349-53. doi:10.1097/01.ijg.0000212260.04488.60
- Turbert, David, and Dan Gudgel. “Does Marijuana Help Treat Glaucoma or Other Eye Conditions?” American Academy of Ophthalmology, 26 June 2019, www.aao.org/eye-health/tips-prevention/medical-marijuana-glaucoma-treament?gclid=EAIaIQobChMImp-l9dzX6QIVRJ3VCh3o3gsHEAMYASAAEgJwWPD_BwE.
- Tomida, I et al. “Cannabinoids and glaucoma.” The British journal of ophthalmology vol. 88,5 (2004): 708-13. doi:10.1136/bjo.2003.032250
- Bouskila, Joseph, et al. “Cannabinoid Receptors CB1 and CB2 Modulate the Electroretinographic Waves in Vervet Monkeys.” Neural Plasticity, Hindawi, 16 Mar. 2016, www.hindawi.com/journals/np/2016/1253245/.
- Thapa, Dinesh et al. “The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation.” Cannabis and cannabinoid research vol. 3,1 11-20. 1 Feb. 2018, doi:10.1089/can.2017.0041
- Miller, S. 2018. op. cit.
- Tomida, I. 2006. op. cit.
- Tubert, D. 2019 June 26. op. cit.
- Boyd, Kierstan. “What Is Glaucoma?” Edited by William Barry Lee, American Academy of Ophthalmology, 6 Jan. 2020, www.aao.org/eye-health/diseases/what-is-glaucoma.
- “Glaucoma.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 14 Nov. 2018, www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839.
- “Secondary Glaucoma.” Glaucoma Research Foundation, www.glaucoma.org/glaucoma/secondary-glaucoma.php.
- Leimuranta, Pinja et al. “Emerging Role of (Endo)Cannabinoids in Migraine.” Frontiers in pharmacology vol. 9 420. 24 Apr. 2018, doi:10.3389/fphar.2018.00420
- Parker, Linda A et al. “Regulation of nausea and vomiting by cannabinoids.” British journal of pharmacology vol. 163,7 (2011): 1411-22. doi:10.1111/j.1476-5381.2010.01176.x