Cannabinoids and Glaucoma: Exploring the Science Behind Marijuana’s Effectiveness

In Florida, glaucoma is listed as a condition eligible for medical marijuana treatment. 

Cannabinoids and other compounds found in marijuana have been studied for their potential effects on glaucoma, a group of painful eye conditions that can lead to blindness. The primary reason most glaucoma patients seek medical marijuana treatment is because of lower intraocular pressure (IOP). IOP is extremely painful. 

Thankfully, studies have shown that cannabinoids can effectively reduce IOP in both healthy individuals and those with glaucoma. This effect is primarily due to the action of THC, the main psychoactive component of cannabis. THC appears to lower IOP by increasing the outflow of aqueous humor, the fluid in the eye, or by decreasing its production.

The article “Cannabis Use for Glaucoma and Associated Pain” delves into how glaucoma, characterized by the deterioration of the optic nerve due to loss of retinal ganglion cells, stands as a major cause of irreversible blindness worldwide. A key modifiable risk factor for glaucoma is IOP. Cannabis, with components like THC and CBD, has been utilized in various treatments, including the reduction of IOP. It also explains the role of cannabinoid (CB) receptors, which interact with THC and CBD. CB1 receptors are mainly found in the central nervous system, while CB2 receptors are linked to the immune and peripheral nervous system.

Besides lowering IOP, cannabinoids may also offer neuroprotective effects. Research suggests that they could protect nerve cells in the retina and optic nerve from damage. This is significant because glaucoma can lead to the death of these cells, resulting in vision loss.

The traditional way of using marijuana—smoking—may not be the most effective or safest method for treating glaucoma. Smoking can lead to fluctuations in IOP and other health risks. Alternative methods like eye drops or systemic administration are being explored, but effective delivery of cannabinoids to the eye remains a challenge.

The use of cannabinoids for glaucoma is not without limitations. The effect on IOP is temporary, requiring frequent dosing. It easily becomes a ritual to relieve pain. Additionally, the psychoactive effects of THC can impact daily activities and mental health. 

Most current medical guidelines suggest that cannabinoids should not replace standard glaucoma treatments such as prescription eye drops and surgery. These conventional treatments are more effective in maintaining a stable IOP and preventing vision loss.

Research into cannabinoids and glaucoma is ongoing. Scientists are exploring ways to maximize the benefits while minimizing side effects, including the development of synthetic cannabinoids and targeted delivery systems.

The American Academy of Ophthalmology’s article “Marijuana and Glaucoma: A Shifting Landscape” emphasizes the moderate reduction in IOP observed in several studies following medical marijuana legalization in many U.S. states. Despite increasing patient inquiries, the lack of substantial scientific support for the benefits of smoking, ingesting, or topically applying cannabis for glaucoma treatment is noted. The Academy, among other eye societies, recommends against using marijuana for glaucoma due to the short-lived nature of its IOP-lowering effects and other concerns. Studies on cannabinoid-containing eye drops have also shown limited efficacy.
It’s important for patients with glaucoma to consult with Dr. Sende about the best treatment strategy for their condition. While cannabinoids offer a potential alternative or supplementary treatment, they are not currently viewed as a replacement for traditional glaucoma therapies.