Yes, mostly in temporary ways. Cannabis can briefly impair night vision, depth perception, and contrast sensitivity, and it often causes red or dry eyes. It also lowers eye pressure for a few hours, but the American Academy of Ophthalmology does not recommend it as a glaucoma treatment. Long-term effects on vision are not well studied.
Short-Term Effects on How You See
Cannabis is the most used drug worldwide, with an estimated 219 million users, according to the authors of a recent review, so these questions affect many people.
The most useful overview is a 2024 narrative review in Clinical Ophthalmology. It reports that cannabinoids may transiently impair night vision, depth perception, binocular and monocular contrast sensitivity, and dynamic visual acuity, according to the review abstract.
Those are skills you rely on for everyday tasks such as driving after dark. Our article on driving performance and vision looks at which visual skills matter most.
Red Eyes, Dry Eyes, and Eyelids
The same review lists dry eyes, red eyes, eyelid tremor, and drooping eyelids among the adverse ocular effects reported with cannabis. It also lists reduced corneal endothelial cell density and neuro-retinal dysfunction.
An ophthalmologist interviewed by The Ophthalmologist described cannabis as associated with a slight decrease in pupil size that is not clinically significant, and noted that law enforcement has observed reduced convergence ability. The interviewee said the literature on cannabis and vision is scant, per The Ophthalmologist. If your eyes feel dry, our guide to hydration and your eyes offers simple habits to try.
Cannabis and Glaucoma: Not a Treatment
This is the most debated question. The American Academy of Ophthalmology acknowledges that some studies found smoked marijuana, or its active ingredient taken in other forms, lowers eye pressure, yet it does not recommend marijuana as a treatment for glaucoma. An ophthalmologist quoted by the Academy said eyedrops that lower eye pressure are far more useful, per the AAO news piece.
The Academy also cites a National Academy of Sciences report concluding that studies suggesting benefits showed only short-term effects on eye pressure, lasting hours, which limits cannabinoids’ potential in treating glaucoma. Glaucoma requires pressure control around the clock. The Clinical Ophthalmology review agrees that there is insufficient evidence to support its use for glaucoma. Our guide to glaucoma versus cataracts versus AMD explains why steady treatment matters.
What About CBD?
CBD is not simply a milder version of THC when it comes to eye pressure. A 2018 study in Investigative Ophthalmology and Visual Science, cited in reporting by The Ophthalmologist, found that THC and CBD differentially regulate intraocular pressure. An eye clinic summarizing that research notes that some findings suggest CBD may raise eye pressure.
That is a reason for caution if you have glaucoma or are at risk, and a reason to mention any CBD products to your eye doctor.
Night Vision: Helpful or Harmful?
The picture here is mixed. The AAO describes a laboratory study in tadpoles suggesting that cannabinoids may enhance night vision, as well as an observation that Jamaican fishermen who used marijuana had excellent night vision. It also describes a human study indicating that regular cannabis use may delay the processing of visual information in the retina.
The ophthalmologist quoted in that piece said marijuana might help some aspects of vision in the short term but might be harmful if used chronically, and that longer-term studies are needed. The Clinical Ophthalmology review, by contrast, lists transient night vision impairment, so the findings do not line up neatly.
Possible Medical Uses Under Study
Researchers are exploring cannabinoids for other eye conditions. The Clinical Ophthalmology review says they are not currently considered a first-line option for any ocular condition. Possible uses include a second-line agent for treatment-refractory blepharospasm, for dry eye disease because of anti-inflammatory properties in the cornea, and for suppressing pendular nystagmus in multiple sclerosis. All of these need further research.
What to Do
Be open with your eye doctor about cannabis use, including edibles, vapes, and CBD products, since it can affect how they interpret your symptoms. Do not substitute cannabis for prescribed glaucoma treatment. If you notice lasting changes in vision, see an eye care professional.
Regular checkups matter for everyone. Our guide to eye exams as you age explains what to schedule.
