Related Experiment Video
Updated: Nov 21, 2025
07:30
Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
7.1K
Effects of cannabis on visual function and self-perceived visual quality.
Sonia Ortiz-Peregrina1, Carolina Ortiz2, Miriam Casares-López1
1Department of Optics, Laboratory of Vision Sciences and Applications, University of Granada, Edificio Mecenas, Av. Fuentenueva s/n, 18071, Granada, Spain.
Scientific Reports
|January 19, 2021
Summary
Smoking cannabis significantly impairs vision, affecting acuity, contrast sensitivity, and night vision. Impaired contrast sensitivity is linked to users
Area of Science:
- Ophthalmology
- Neuroscience
- Pharmacology
Background:
- Cannabis is a widely abused substance globally.
- Understanding its ocular effects is crucial for public health.
Purpose of the Study:
- To investigate the impact of smoking cannabis on various visual functions.
- To correlate objective visual changes with users' subjective perceptions.
Main Methods:
- Assessed visual acuity, contrast sensitivity, stereoacuity, accommodation, straylight, and pupil size in 31 cannabis users.
- Compared pre- and post-smoking visual function.
- Used logistic regression to link visual tests to self-perceived effects.
Main Results:
- Smoking cannabis adversely affected all measured visual parameters (p < 0.05).
- Two-thirds of users reported worsened vision after smoking.
- Reduced contrast sensitivity at 18 cpd was the sole predictor of self-perceived visual decline (OR: 1.135, p = 0.040).
Conclusions:
- Cannabis use negatively impacts visual system function.
- Impaired contrast sensitivity may explain users' subjective perception of visual impairment after cannabis use.
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