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.
In this study, which had the approval of the Human Research Ethics Committee of the UGR , 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 results showed that, following consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision , the ability to focus, and glare sensitivity significantly worsened.
The study found a negative effect on all of the visual parameters evaluated, with the effect of cannabis on some of the parameters being analysed for the first time in this research.