Smoking Cannabis Can Impair Vision That Users Are Not Aware Of

According to a University of Granada study, a cannabis user may experience an adverse effect that affects vision without perceiving that it's manifesting. The research discovered that several vision changes developed after smoking cannabis. 

Cannabis is one of the most abused drugs in the world. Based on the European Monitoring Centre for Drugs and Drug Addiction in 2019, around 15% of young Europeans between 15 and 34 years old smoked cannabis. Spain is one of the many countries with the highest occurrence of cannabis use. The frequency of consumption has inflated in the past few years. 

The goal of this research was to investigate the effects of smoking cannabis on vision and to connect these to those recognized by the user. The visual function evaluation was conducted in a baseline session, including after smoking cannabis. 

The new study from the university's Department of Optics looked into the changes in the vision due to using cannabis, including a user's perception. There are 31 participants who used cannabis products and were evaluated while being sober. They were also assessed while under the influence. 

The data shows that cannabis use affected all measured parameters, which showed negative effects. Users encountered "notably impaired" focusing ability. It also includes light glare sensitivity, visual acuity, contrast sensitivity, night vision disturbance, pupil size, and 3D vision. In spite of the changes, 30% of the participants claimed they didn't recognize any changes in their vision. 

Researchers found that smoking cannabis has substantial side effects on all reviewed visual parameters. Additionally, the participants are divided into two groups, whether if they noticed their vision to have exacerbated after smoking cannabis.

Almost all of the remaining participants noted that they experienced only "moderately" worsened visual perception compared to when not intoxicated. Researchers suggest that the adversary impact on vision can present a danger during different everyday activities. When collaborated in the user's absence of cognizance of the expanse of changes, educational drives on the issue are crucial.