Blind Faith? Considerations About Medical Marijuana & Glaucoma

Ophthalmology concept. Male patient under eye vision examination

Generally speaking we tout the potential of marijuana, advocating its medical advantages left, right, and center. We praise its benefits for pain reduction, epilepsy, nausea, autism, MS, anorexia, and countless other conditions — the list is positively exhaustive. And yet, we would not advocate for marijuana unequivocally. One case where we do not outright recommend marijuana’s medicinal properties is with glaucoma.

Glaucoma is a condition where increased pressure within the eyeball causes damage to the optic nerve, risking and often causing blindness, especially among the elderly. Several advocates of medicinal marijuana cite small-study or anecdotal evidence that cannabis can lower intraocular pressure (IOP) in people with glaucoma. However, these products are less effective than safer prescription drugs.

Side Effects

In order to produce a clinically-relevant pressure reduction on IOP, frequent inhalation is required because the effect only lasts a few hours. This means one would need to smoke a joint every 3 hours. The number of significant side effects generated by long-term oral use of marijuana or long-term inhalation of marijuana smoke can make it a poor choice in the treatment of glaucoma, a chronic disease requiring proven and effective treatment.

The only marijuana currently approved at the US-federal level for medical use is Marinol, a synthetic form of tetra hydrocannabinol (THC) — the most active component of marijuana and the one which produces the “high.” Marinol was developed as an antiemetic (an agent that reduces nausea used in chemotherapy treatments), which can be taken orally in capsule form.

But it turns out that the effects of Marinol in general, and on glaucoma in particular, are not impressive compared to the real thing. Yet in terms of glaucoma, no studies have shown that marijuana or any of its approximately 400 chemical components can safely and effectively lower intraocular pressure better than the variety of drugs currently on the market. In addition, according to the Glaucoma Research Foundation, while marijuana might lower intraocular pressure, it also lowers blood pressure, which in turn could provide less blood to the optic nerve.

IOC pressure notwithstanding, the issue of pain still remains. That is to say, while medical marijuana might not help with curing glaucoma, it can provide a great sense of pain-relief comfort to glaucoma sufferers. Part of the reason for legalizing marijuana is to allow adults to make the best choices. Glaucoma, it seems, is a prime example of such a dilemma, best discussed with your medical marijuana supportive care provider.

Originally published at on May 12, 2016.