Cannabis is an effective treatment for glaucoma, though short lived. And the up and down changes to eye pressure can actually make things worse.
In the 1970s, eye-opening studies revealed that cannabis was an effective treatment for glaucoma. But in the decades since, medical scientists have been re-thinking cannabis-based therapy for eye diseases. Have they debunked one of the first and best-known uses for medical cannabis?
The Journal of the American Medical Association published a landmark paper in September of 1971 that touted the “impressive” benefits of what it called “marihuana” on intraocular pressure—the biggest symptom of glaucoma.
A Youth Protest Against Reefer Madness
The issue itself was supposed to be an announcement. In addition to the glaucoma study, the issue publicized a survey of American and Canadian medical students’ views on cannabis, showing that they had a much more liberal stances on its use. It also included a strongly worded letter to the editor that took the medical community to task for its alarmist view of cannabis use amongst adolescents.
The journal’s intent was clear: The AMA was embracing a forward-looking stance on cannabis. The young guard was clearly divested of any “Reefer Madness” attitudes. Moreover, respectable physicians were finding real medical value in the plant. A sea change was underway.
A Sea of Change?
The National Eye Institute joined the AMA in its celebration of a new treatment for the blindness-causing disease. Years before Jimmy Carter won the White House on a platform that promised to consideration decriminalization, the counter culture moment had come to American medicine.
But the promised sea change never happened. And the groundswell fomenting around the glaucoma research petered out as most ophthalmologists refused to seriously consider treating their patients with cannabis.
And they were probably right.
Cannabis Can Alleviate Pressure in the Eye
Pressure in the eye usually causes glaucoma. This slowly strangles and kills the optic nerve. First, the peripheral vision goes; then the patient’s sight range narrows further, leading to tunnel vision and, finally, total blindness. It’s chronic and there is no known cure.
Cannabis treated this problem by alleviating the pressure inside the eye, allowing the optic nerve a respite from constant strain. The problem is that it only provides temporary relief to a persistent condition. In order for cannabis to effectively treat glaucoma, patients would need to dose themselves up to eight times a day. And, because people develop a cannabis tolerance, treatment progression would require higher doses.
Smoking cannabis was just not the right answer—but that doesn’t mean it’s not useful.
While we know that cannabis reduces pressure in the eye, the exact means by which that occurs remains a mystery. And, as every good medical drama fan knows, any physiological mystery is an opportunity.
Continuing Decades’ Old Research
New research is focused on discovering how the active ingredients within cannabis are able to affect the eye and slow the progression of glaucoma, if only briefly. Instead of affecting the central nervous system, today’s research points to the CB1 and CB2 receptors in the endocannabinoid system as the probable action agents in the fight against blindness.
If the prevailing theory is correct, it opens the door for a synthetic cannabinoid-based therapy. Scientists could, in theory, engineer an artificial cannabinoid that also targets the CB1 and 2 receptors, but has a longer-lasting effect and whose effectiveness doesn’t decrease over time.
Before that happens, however, there is still reason to believe that good, old-fashioned cannabis use has an important place in glaucoma treatment.
Symptom Alleviation, and Future Treatments
Although glaucoma’s initial stages are pain-free, negative feelings can mount as the optic nerve starts to wither. Those side effects include nausea and anxiety—conditions that cannabis treats very well. Combined with temporary relief from optic nerve pressure, cannabis provides a great medicine for advanced glaucoma patients.
Future directions for cannabis-based treatment can play out in two ways. The first focuses on finding the specific compounds within cannabis that most effectively relieve intraocular pressure. Cannabigerol (CBG), for example, is a cannabinoid that does not have psychotropic effects, but has been shown to be effective against degenerative diseases like Huntington’s.
Because glaucoma is also a degenerative disease affecting the eyes and brain, it’s possible that some of the same benefits could be found in glaucoma by pursuing CBG therapy.
The second avenue for future treatment is the synthetic cannabinoid route, which has also shown real promise. The compound dexanabinol, also known as HU-211, has also been shown to have neuroprotective abilities and has been shown to be safe in clinical trials.
So while the future of glaucoma is still in the shadows, cannabis-based treatment remains a bright spot.
