Effect of Cannabidiol (CBD) on Vision and Driving

Effect of Cannabidiol (CBD) Consumption on Visual Function and Driving Performance

The use of cannabis with ∆9-tetrahydrocannabinol (THC) content has been shown to have negative effects on vision and driving. The use of other cannabinoids, such as cannabidiol (CBD), which is not attributed with a psychoactive effect, is increasing significantly. This project aims to investigate whether consuming CBD can negatively affect visual function by assessing a wide range of visual parameters and whether these changes may pose a risk for everyday activities such as driving.

Study Overview

• Status: Active, not recruiting
• Conditions: Cannabis Use
• Intervention / Treatment: Other: Placebo (CBD 0%); Other: CBD 15%; Other: CBD 30%

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• Spain
  • Granada, Spain, 18071
    • University of Granada

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Being an occasional cannabis and/or cannabidiol user
• Have a current driving licence
• Have at least one year's driving experience
• Drive at least once a week
• Monocular visual acuity of at least 6/6 (Snellen) with habitual correction for driving
• Absence of binocular disorders

Exclusion criteria:

• Certain past or present medical conditions
• Current cannabis or alcohol use disorder
• Use of other drugs
• Pregnancy or lactation
• Simulator sickness.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo (CBD 0%); Participants are required to vaporize a placebo at 0% CBD concentration	Other: Placebo (CBD 0%); Participants are required to vaporize placebo at 0% CBD concentration
Experimental: CBD 15%; Participants are required to vaporize CBD at a concentration of 15%.	Other: CBD 15%; Participants are required to vaporize CBD at a concentration of 15%.
Experimental: CBD 30%; Participants are required to vaporize CBD at a concentration of 30%.	Other: CBD 30%; Participants are required to vaporize CBD at a concentration of 30%.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Overall Driving Performance Score (ODPS) after cannabidiol vaporization	To obtain the ODPS, Z-scores were calculated from individual parameters such as the standard deviation of the lateral lane position or the distance travelled into the opposite lane. The z-score is defined as a measure of how many standard deviations an individual value is below or above the group mean. The average Z-score of the individual driving variables is called the ODPS.	Participants are assessed 20 minutes after vaporization
Change in motion detection sensitivity after cannabidiol vaporization	The subject has to indicate the direction of movement of a pattern of moving dots. The percentage of correct answers is obtained for different degrees of coherence.	Participants are assessed 20 minutes after vaporization
Change in contrast sensitivity after cannabidiol vaporization	Contrast thresholds are obtained for different spatial frequencies	Participants are assessed 20 minutes after vaporization
Change in visual acuity after cannabidiol vaporization	Visual acuity is assessed with a commercial test for distance vision.	Participants are assessed 20 minutes after vaporization
Change in fixations after cannabidiol vaporization	The number of fixations made on different stimuli of interest in a task environment is counted using an eye tracker system.	Participants are assessed 20 minutes after vaporization

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Driving simulator: standard deviation of the lateral lane position (SDLP)		Participants are assessed 20 minutes after vaporization
Distance travelled outside the lane	The SDLP assesses the lane weaving that the subject performs in the lane and indicates whether the vehicle's position is consistent.	Participants are assessed 20 minutes after vaporization
Mean speed	Average speed is obtained and analyzed in relation to the speed limits for different sections.	Participants are assessed 20 minutes after vaporization
Angular velocity of the steering wheel	The angular velocity of the steering wheel is a metric that indicates the subject's ability to maintain the vehicle's position.	Participants are assessed 20 minutes after vaporization

Collaborators and Investigators

• Sponsor: Universidad de Granada

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2023
• Primary Completion (Actual): September 30, 2023
• Study Completion (Estimated): December 31, 2025

Study Registration Dates

• First Submitted: February 29, 2024
• First Submitted That Met QC Criteria: March 13, 2024
• First Posted (Actual): March 21, 2024

Study Record Updates

• Last Update Posted (Actual): March 22, 2024
• Last Update Submitted That Met QC Criteria: March 20, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: cannabis; vision; cannabidiol; driving performance
• Additional Relevant MeSH Terms: Mental Disorders; Chemically-Induced Disorders; Substance-Related Disorders; Marijuana Abuse
• Other Study ID Numbers: C-EXP-194-UGR23

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No