Glaucoma is a disease that damages the optic nerve, causing pain, pressure, and sometimes partial or total blindness. And in many states, glaucoma is a qualifying condition for medical marijuana.
Glaucoma refers to the buildup of fluid in the eye resulting in increased intraocular pressure (IOP). As the nerve deteriorates over time, blind spots develop in the visual field, impairing vision or causing complete blindness.
There are two types of glaucoma: open-angle glaucoma and angle-closure glaucoma. Open-angle glaucoma is caused by chronic pressure inside the eye. For many sufferers, the effect of open-angle glaucoma is so gradual that they may not notice a change in vision until the condition is at an advanced stage. Over time, this pressure damages the optic nerve in the back of the eye, leading to permanent vision loss.
Angle-closure glaucoma is more severe and less common. In angle-closure glaucoma, fluid builds up close to the iris which can lead to blindness very quickly, especially as you age. Glaucoma is one of the leading causes of blindness for people over the age of 60. Symptoms can include severe headaches, eye pain, nausea and vomiting, and blurred or distorted vision.
Glaucoma is treated by lowering Intraocular Pressure (IOP). Depending on your situation, your doctor may prescribe eye drops, oral medications, laser treatment, surgery, or a combination of these.
Once a glaucoma patient’s vision loss begins, it can’t be recovered. This is why it’s important to have regular eye exams that include measurements of your eye pressure. If glaucoma is recognized early, vision loss can be slowed or prevented. Once diagnosed, most patients need glaucoma treatment for the rest of their life.
In 1974, a 26-year-old man with advanced glaucoma named Robert Randall observed that the halos around lights he experienced because of his high IOP disappeared after he smoked marijuana. He fought and won a landmark court case after federal criminal charges for growing marijuana were dropped because he was able to persuade the judge that his marijuana use was a medical necessity. Since then, 29 states and Washington D.C. have passed laws that allow patients with glaucoma to use medical marijuana.
Medical marijuana is not a cure for glaucoma. There is no cure for the condition, and even with treatment, patients who are diagnosed with glaucoma may eventually go blind. People who cannot or choose not to take typical glaucoma medications may consider medical marijuana to lower their eye pressure.
While there’s no evidence of a direct correlation between THC and treating glaucoma patients, researchers know that endocannabinoid receptors are prevalent in eye structures. A 2018 Glaucoma Today article notes that while studies are scant, the cannabinoid THC has been shown to at least temporarily lower IOP in 60-65% of patients, both with and without glaucoma.
CBG (cannabigerol) is one particular minor cannabinoid that has piqued researchers’ interests with respect to possible treatment as a glaucoma medicine. CBG is a powerful vasodilator and has neuroprotective effects thought to fight inflammation, pain, nausea, and slow the proliferation of cancer cells. Research has shown it also significantly reduces intraocular eye pressure caused by glaucoma. Strains high in CBG would also be beneficial for treating conditions such as inflammatory bowel disease, Crohn’s disease, and cancer. While not present in large quantities in most strains, many products in dispensaries now include CBG.
Leafly notes that two cannabinoid agonists—WIN55212-2 and anandamide—and several cannabinoids, including CBD and CBG, may be good candidates to develop as therapeutic agents for glaucoma, particularly because even when administered topically (directly to the eye), they are well tolerated.
Author: Gabrielle Dion Visca
Gabrielle has been writing and editing professionally for the medical and wellness industries for more than 20 years. She’s held positions with The Journal of Pediatrics, Livestrong, The Cincinnati Enquirer, and Patient Pop. She currently writes articles about medical marijuana for Duber Medical, and is the founder of the Ohio cannabis journalism non-profit, MedicateOH.