Missouri recently passed a law to legalize the sale of marijuana for recreational purposes. It’s been legal in Illinois since 2020 and medical marijuana has been legal in both states for several years now. While there is still much about how marijuana affects the eyes and body we do not know, there are some things we know that everyone should be aware of before partaking. We see the effects of cannabis because we have cannabinoid receptors all over our body, including the eye. The human body naturally produces cannabinoids.
Can I Use Marijuana to Manage My Glaucoma?
A question I get all the time is: can I use marijuana to manage my glaucoma? And the short answer is no. While consuming marijuana will lower eye pressure, it only does so temporarily. The effect wears off after a couple of hours. You would have to be constantly using it, and because it impairs our ability to function safely, constantly using it is not recommended. An eyedrop once or twice a day is sufficient to safely and effectively lower the pressure to manage glaucoma in most cases and is the preferred method.
How Marijuana Affects the Body
One way marijuana affects the entire body is by temporarily lowering blood pressure. This will cause blood vessels to dilate to increase blood flow to the organ. The way this presents in the eye is with redness. The blood vessels on the white part of the eye, or the sclera, will dilate and cause a pinkish-red hue. Smoke in the environment can also irritate the ocular surface and cause discomfort, dryness, and further worsening of redness.
Interesting Studies About Marijuana and the Eyes
A few studies have been released recently with interesting findings- some positive, some negative. The important thing to consider in both studies is that the sample size is either small or not human, so may not be entirely accurate, but opens the gateway to further much-needed research. More investigation needs to be done to accurately determine marijuana’s effects on the eyes, both short and long-term.
The first study was performed in tadpoles (fun fact: their retinas have similar properties to ours) and determined that marijuana may improve night vision. Researchers applied a synthetic cannabinoid to the retinas of tadpoles and found that certain cells within the retina responded with increased sensitivity to light and even reduced the time it took for the cell to respond to dim light. This study was performed due to the numerous anecdotal reports from fishermen that using marijuana improves night vision. It’s possible that regular users can see more detail sooner in dark environments compared to non-users.
Another study, this one with humans, observed how using cannabis affects the retinal ganglion cells. Retinal ganglion cells are specialized and very important cells that essentially take all the visual information collected from the retina and relay it to the brain for processing. You can think of them like messengers. This study compared regular marijuana users with non-users. The results showed that the response time of the ganglion cells in marijuana users was significantly reduced or that they took longer on average than a cell from non-user to respond. This may or may not significantly affect the vision of a regular user, but there’s no way to know for certain until more studies are done.
Sales of recreational marijuana in Missouri earned more than $5 million in revenue on the first day alone. Hopefully, the widespread use in the coming years provides us with some much-needed clarity in the form of further research.