Smoking cannabis is linked to alteration of key visual functions including visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity.
- Smoking cannabis/marijuana impairs visual processing
- Marijuana is the most commonly used illegal drug in the United States, according to CDC
- Awareness campaigns are needed, as the visual deterioration can pose a danger when performing everyday tasks
This study, led by Carolina Ortiz Herrera and Rosario González Anera, has been published in the journal Scientific Reports. Its main author, Sonia Ortiz Peregrina, explains that cannabis use is on the rise despite being an illegal drug. According to the national Survey on Alcohol, Drugs and Other Addictions in Spain 2019-2020, cannabis use nationally has increased since 2011, with 37% of Spanish adults having used this drug at some time. Approximately 10% consumed it in the last year.
In this study, which had the approval of the Human Research Ethics Committee of the UGR (ref. 921/CCEIH/2019), an exhaustive visual trial was conducted on 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 subjects 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.
Source-Eurekalert