Research study · Translational Vision Science & Technology · 2025
Influence of Cannabidiol Use on Visual Function and Optical Quality: A Randomized Controlled Trial
Verified on PubMed Oxford CEBM Level 1B: Randomized Controlled Trial
A 2025 randomized controlled trial in Translational Vision Science & Technology tested cannabidiol. It made no difference to eyesight in this small study. This study suggests that a single session of cannabidiol vapor at the amounts tested does not noticeably blur or weaken vision in healthy young adults.
In plain language
Study overview
Thirty young adults who sometimes use cannabidiol, a non-intoxicating part of the cannabis plant, took part in this study. Each person breathed in vapor on three separate days: one with no cannabidiol, one with a low amount, and one with a higher amount, without knowing which was which. Researchers then checked many aspects of their eyesight.
Findings
It made no difference to eyesight in this small study. Sharpness, the ability to see fine detail, depth perception, night vision, and the clarity of the eye's optics all stayed the same whether people had the low amount, the higher amount, or the empty vapor.
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The deeper readScientific analysis
Purpose: To study the influence of different concentrations of vaporized cannabidiol (CBD; 0%, 15%, and 30%) on visual function and optical quality. Methods: A randomized, crossover, double-blind, placebo-controlled, experimental study was conducted. A total of 30 participants with a mean age of 26.0 ± 6.3 years completed the study. Placebo (0 mg of CBD), 15% (16 mg of CBD), and 30% (32 mg of CBD) concentrations of CBD were employed. Visual function was evaluated through various tests, including pupil size, static and dynamic visual acuity, contrast sensitivity, dot motion detection, visual disturbance index (VDI), and stereoacuity. Optical quality was assessed by log(s), modulation transfer function (MTF) cutoff, objective scattering index (OSI), and Strehl ratio. Self-perceived visual effects were also recorded. Results: There was no significant impairment of static and dynamic visual acuity. Contrast sensitivity was unaffected by CBD use. Mean dot motion detection showed no differences among the three concentrations. In optical quality, none of the parameters worsened under CBD use. No changes were observed for the VDI. In addition, no deterioration was observed for stereoacuity at distance or near. No changes in pupil size were found after CBD consumption. Conclusions: This non-psychotropic CBD did not appear to adversely affect vision and seems to be a safe substance in the short term at the concentrations assessed. Translational Relevance: The use of this cannabinoid would not be dangerous for tasks that rely heavily on vision. This study could be useful and helpful for evidence-based decision-making for public health policy on its use.
The paper
Citation
Martino F, Ortiz-Peregrina S, Casares-López M, Granados-Delgado P, Castro-Torres JJ, Anera RG Influence of Cannabidiol Use on Visual Function and Optical Quality: A Randomized Controlled Trial. Translational Vision Science & Technology (2025). PubMed 41071032 · DOI
Limitations the authors noted
Small, homogeneous sample of 30 young occasional users limits generalizability. Single-session short-term design; long-term effects not assessed. Higher CBD doses not studied. Only 63% of placebo and 37–43% of active sessions correctly identified (imperfect blinding). Attrition of 13 of 43 enrolled participants; per-protocol analysis only. No formal test for period or carryover effects. Some secondary outcomes not prespecified in trial registration.
In practice
Why this matters
This study suggests that a single session of cannabidiol vapor at the amounts tested does not noticeably blur or weaken vision in healthy young adults. It does not show that cannabidiol is safe for vision over time, at higher amounts, in other forms, or in older people or those with eye conditions, and the small group and single-session design leave those questions open.
Frequently asked questions
Clinical Questions & Answers
What were the primary clinical findings in this clinical evaluation of CBD?
It made no difference to eyesight in this small study. Sharpness, the ability to see fine detail, depth perception, night vision, and the clarity of the eye's optics all stayed the same whether people had the low amount, the higher amount, or the empty vapor.
What study limitations or clinical safeguards should patients keep in mind?
Small, homogeneous sample of 30 young occasional users limits generalizability. Single-session short-term design; long-term effects not assessed. Higher CBD doses not studied.
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Reviewed by Dr. Caplan on October 24, 2026.
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