One in Six Eye Clinic Patients Used Cannabis Recently, and Nearly Half With Glaucoma Wanted to Try It

Recent marijuana use (past month): 15.7%. Regular users: 8.2%. Daily users: 4.5%. Among glaucoma patients, 44.2% were interested in using marijuana. Patients who used marijuana less than 24 hours before their exam were significantly more likely to know it lowers IOP (p = 0.02). Beliefs about marijuana effectiveness, IOP lowering, and fewer side effects predicted interest in use.

Survey of 134 patients at four University of Minnesota eye clinics during two collection periods (October 2022-January 2023, July-August 2024). Questions covered cannabis use patterns, knowledge of effects on IOP, and attitudes toward marijuana for glaucoma.

Cannabis temporarily lowers intraocular pressure, which can mask true readings during eye exams. With 15.7% of patients using recently and many not volunteering this information, ophthalmologists may be making diagnostic and treatment decisions based on falsely low IOP measurements.

The temporary IOP-lowering effect of cannabis creates a diagnostic blind spot. If patients use cannabis before eye exams, their IOP may appear normal when it is actually elevated, potentially leading to missed or delayed glaucoma diagnoses or false reassurance about treatment effectiveness.

Small convenience sample from one university's clinics limits generalizability. Self-reported cannabis use may be underreported. The survey did not verify IOP measurements against cannabis use timing. Interest in marijuana for glaucoma does not equal actual use.