Southwest, FL | Marijuana Treats Glaucoma | Cataract & Refractive Institute of Florida

Description of marijuana and its use for treating glaucoma. Marijuana lowers the intraocular pressure by 25% but is very short acting. It would require smoking marijuana every 3 to 4 hours in order to lower the eye pressure.


Dr. Croley: Hello. I'm Dr. Croley, and welcome to Case of the Day. Typically we talk about an interesting case, but today we're going to shift focus a little bit. I had a person come in who has glaucoma, who asked me about using marijuana as a treatment for glaucoma. Since there's been some new laws in different states that have passed, I thought it might be appropriate to go over what marijuana has to do with glaucoma, and can it treat glaucoma. I thought I'd be a little smart come up with all kinds of terms and names for joint, reefer, different things of the list of names of different slang words for marijuana. I Googled it, and instead of having maybe 15 or 20, which I thought, ended up being several hundred words as far as a slang for marijuana goes. So decided not to go to that route.

Dr. Croley: But anyway, so first thing. Marijuana is a plant, obviously, that the stems and flowers are crushed up and then taken, either by eating a brownie, with the old brownies, or by smoking. There's over 400 different chemicals actually in the marijuana plant. Most of them are cannabinoids, and the active ingredient, the major active ingredient, the psychoactive part, is THC. So that's the major component that is felt to have its action as far as the the benefits for some people that it has for nausea and different things associated when people have cancer and cancer treatment. But there's been actually a lot of research done in glaucoma and marijuana in the past. So we'll go over a little bit about that.

Dr. Croley: So what is glaucoma? In simple terms glaucoma means that the pressure inside your eye is higher than what your eye can tolerate and typically, usually, is higher than normal. The normal pressure's 10 to 21 millimeters of mercury. The fluid is produced by a gland behind your pupil. It goes in front of your lens, through the pupil, and fills up the front of your eye and drain through a meshwork here, like cheesecloth, into Schlemm's Canal and then into your blood system. So there's a constant production and a constant flow of fluid out of your eye. We're not sure exactly the mechanism of how marijuana lowers the eye pressure, but it's felt that the studies were done that the outflow, that is the flow out of your eye, was increased with the use of marijuana. We think that's the most likely mechanism of how it works.

Dr. Croley: They tried actually making an eye drop out of THC and instilling that, and it really didn't lower the eye pressure very much surprisingly. So then they also tried with ingesting marijuana, and that lowered the eye pressure but not significantly. It turns out that actually smoking marijuana was the best route of lowering the eye pressure. And in fact, in the studies, it lowered the eye pressure by 25%, so it did have a significant reduction in the eye pressure. The problem is that its length of action was three or four hours and then the pressure would go back up. So that has been a major problem with trying to use marijuana to treat glaucoma because of its short action.

Dr. Croley: So the other thing, as far as using marijuana to treat glaucoma, this is a chronic life-term longterm disease, so you're going to have to be doing this, you treating it for the rest of your life. Someone who may have cancer who may be terminal, then the other side effects aren't as important, but when someone who's going to be treating glaucoma for a long time, marijuana does increase your heart rate, it lowers the blood pressure, both diastolic and systolic. There was a study recently out of New Zealand that it may contribute to strokes. It may have an effect on your immune system. There's evidence of maybe increasing cancer risk, and in women who are pregnant, it has caused some pregnancy problems. And then you have the psychotropic effects as well.

Dr. Croley: Marijuana does not turn out to be a great choice as far as treating glaucoma because it looks like it has to be smoked to be useful for glaucoma. And then you would have to be smoking this every three or four hours around the clock. So you'd have to get up in the middle of the night and smoke your marijuana in order to keep your eye pressure low, and no one's going to do that. And you would be actually basically stoned all the time, so you couldn't function in life. You might treat your glaucoma, but you would have trouble functioning as much as you would have to smoke to keep your eye pressure down.

Dr. Croley: So it turns out that marijuana does lower eye pressure by 25%, but it's not a longterm answer to treating glaucoma. If they come out with something that does work, far as an eyedrop or something else, where you would still be able to function, you wouldn't get the big psychotropic effect, then maybe someday there would be some way it can be used. Maybe there's some other chemical in the plant that's smoked, combined with the THC, that causes this pressure-lowering effect, but really nobody knows.

Dr. Croley: So if you have any questions about this or any other subject, please feel free to contact us through the website. If not, may God bless you with healthy eyes and great vision.