“I’ve been told that medical marijuana treats glaucoma. Is this true?”

Our question this morning on 103.3 US Country comes from an anonymous listener, but it is one that I sometimes get asked by patients.

In summary, the answer is NO. And I’ll explain why.
 

What is glaucoma?

There are different types of glaucoma but they all result with damage to the optic nerve. This nerve connects your eye to your brain so that your vision can be processed. Glaucoma causes a progressive loss of nerve cells. If left untreated, glaucoma results in peripheral vision loss and eventual total blindness. If the signal cannot travel from your eyes to your brain via the optic nerve, then you cannot see.
 

How does eye pressure affect glaucoma?

The most common type of glaucoma is called primary open angle glaucoma. Historically, it was once simply thought that high intraocular pressure (IOP) caused this type of glaucoma. As the research has continued, we now know that there is much more to it than just that. We know that there is a dynamic relationship between IOP and cerebrospinal fluid (CSF). We also know that glaucoma is affected by the amount of oxygen that reaches the optic nerve.

At this point in time, our only method of treatment for glaucoma is to lower IOP. Someday in the future, we may have other treatments available that can address the other contributing factors.
 

How does marijuana affect eye pressure?

It is true that marijuana will lower IOP. This is why the thought process exists that marijuana must be able to treat glaucoma. The problem is that marijuana only lowers IOP for a short period of about 3 to 4 hours. Also, it will do so unevenly with the effect tapering off as the levels decrease in your body.

With glaucoma treatment, it is critical to maintain steady and consistent IOP-lowering over a 24-hour period. Marijuana is simply unable to do that. When you have peaks and dips in IOP, it can actually cause glaucoma to worsen. Marijuana certainly causes peaks and dips in IOP, due to it’s short duration action that is uneven. Also, since the delivery method for medical marijuana varies greatly, that is another factor that makes the IOP-lowering effect extremely unpredictable.

In addition, marijuana will lower your blood pressure. In some individuals, this would be desirable. However, this effect also causes oxygen perfusion pressure to be lower, causing less oxygen to reach the optic nerve. We do know that oxygen flow plays a role in glaucoma, and that a lack of oxygen will cause worsening of glaucoma. Thus, this is another aspect where marijuana could cause glaucoma to worsen.
 

Is there a place for medical marijuana in glaucoma treatment?

At this point in time, NO. We need more research on glaucoma and more research on medical marijuana to better understand the relationships.

The content on this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.