Self-reported Visual Function After Non-medical Cannabis Use: A Cross-sectional Survey

Background: Despite strict legal restrictions, cannabis use is increasing in Sudan, yet its effects on visual function remain poorly understood. This study aims to estimate the prevalence of self-reported visual changes and examine their relationship with patterns of non-medical cannabis use. Methods: The study was conducted in Sudan, an understudied context for cannabisrelated visual effects. A descriptive cross-sectional survey was carried out among 60 cannabis users in Khartoum using a non-probability sampling method. Most participants were male (86.7%). Structured interviews collected demographic data, cannabis use history, and self-reported visual symptoms, including light sensitivity, visual field changes, and distance and near vision problems. Results: Participants were mainly young adults aged 18–31 years, with 83.4% reporting cannabis initiation before age 20. Visual disturbances were common: 90% reported photophobia, 66.7% experienced constricted visual fields, 46.7% reported blurred distance vision, and 33.3% reported near-vision difficulties. Hallucinations were reported by 50% of participants. Notably, 60% experienced potentially life-threatening events related to visual impairment within 3 hours of their most recent cannabis use, most often road collisions or near-miss incidents, with a median onset time of 1.9 hours. This association remained significant after controlling for alcohol co-use (Fisher’s exact P = 0.041). No significant associations were observed between visual symptoms and demographic or usage characteristics. Conclusion: Early initiation, prolonged cannabis use, and polydrug consumption appear to increase the risk of visual disturbances. High prevalence of life-threatening incidents highlights the need for early intervention, public education, and integrated substance-use assessments to reduce visual and safety risks.