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No studies to date have looked at marijuana in AMD. Marijuana is a hallucinogenic drug, which is harmful to a number of parts of the body including neurons. The retina and optic nerve are made of neurons and thus its use can be harmful for vision in general by causing damage to neurons in the brain and optic nerve.
Smoking reduces blood supply by (1) vasospasm induced by nicotine, (2) atherosclotic narrowing of vessels, and (3) thrombotic occlusions. Vasospasm induced by smoking causes enlargement of the normal blind spot and reduced threshold of differential brightness. Visual perception is additionally depressed by the levels of carboxyhemoglobin commonly found in the blood of smokers, a hypoxic effect superimposed on the reduced blood supply. In addition, partial or complete blindness due to retinal artery thrombosis is at least twice as frequent in smokers as in nonsmokers. Current smokers of 20 or more cigarettes a day had a twofold to threefold increased risk of developing AMD with vision loss compared with those who had never smoked. Women smoking 25 or more cigarettes a day had 2.4 times the risk of developing AMD. Women with a history of smoking had a twofold increased risk of AMD, with little drop in risk even in those who had stopped smoking more than 15 years before (JAMA 1996;276:1141-6).
Answered by: W. Barry Lee, MD
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