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Does Smoking Weed Affect our Vision?

Updated: Dec 4, 2021

With the recent legalization of marijuana use in Canada, cannabis use has soared in popularity. However, there isn’t really any clear answer about the effects of marijuana use on one’s vision, but two new studies seek to close the knowledge gap.

A study from McGill University in Montreal, Canada, which was conducted on tadpoles, suggests that there may be a linkage between marijuana usage and increased night vision. This was based on an observation of Jamaican fishermen who used marijuana regularly, as they had excellent night vision. The researchers applied a synthetic cannabinoid (an organic chemical that interacts with drug receptors in the brain) to the eye tissue of tadpoles. They found that these cannabinoids made retinal cells more sensitive to light, thus improving the speed at which the eye responds to stimulus, thus resulting in increased night vision.

Another study suggests the opposite—that marijuana negatively impacts vision. This study suggests that marijuana slows retina processing in humans who use marijuana. When comparing the retina in marijuana users vs non-marijuana users, researchers found that there was a delayed response in the retinal ganglion cells of users. These cells are responsible for transmitting electrical impulses from your eyes to your brain (aka your visual processing).

It’s important to note that neither of these studies addresses the long-term impacts of marijuana use, and that in both cases, the benefits/harms were quite minor. Therefore, there isn’t a real way to tell whether marijuana may benefit vision in the short term but harm it in the long term, or vice versa.

Currently, there are many rumours floating around about marijuana as a treatment for glaucoma, but the American Academy of Ophthalmology states that they do not recommend marijuana to treat glaucoma. We must abstain from making “blanket statements” about marijuana’s effect on the eyes until long-term studies are conducted, but for now, these two studies reveal some fascinating potentials.


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