In a new study from the University of Granada, researchers found that smoking cannabis strongly alters key visual functions, such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity.
Yet more than 90% of users believe that using cannabis has no effect on their vision, or only a slight effect.
In the study, the team examined the effects of smoking cannabis on vision compared to the effect that the users themselves perceive the drug to have on their vision.
They tested visual functions in 31 cannabis users, both when they had not consumed any substance in advance and also when they were under the effect of the drug.
The researchers also studied the participants’ perception of the visual effects of having consumed this drug.
The results showed that, following consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity significantly worsened.
Despite this, not all people reported a worsening of their vision after smoking cannabis. Indeed, 30% reported that their vision had not suffered at all, while 65% responded that it had worsened only slightly.
The researchers note that the visual parameter that could be most strongly linked to users’ perception of the visual effect is contrast sensitivity.
The study found a negative effect on all of the visual parameters evaluated, with the effect of cannabis on some of the parameters being analyzed for the first time in this research.
These results, together with the lack of awareness that the participants presented about the visual impairment caused by smoking cannabis, indicate the need to carry out awareness-raising campaigns, as this visual deterioration can pose a danger when performing everyday tasks.
If you care about marijuana, please read studies about what you should know about marijuana and your health and findings of marijuana use linked to higher risk of high blood pressure, stroke, heart disease.
For more information about cannabis and wellness, please see recent studies about how marijuana could harm your heart and blood pressure health and results about vaping vs. smoking cannabis: Which is safer?
The study is published in Scientific Reports. One author of the study is Carolina Ortiz Herrera.
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