Some research suggests canabis reduces eye pressure because of glaucoma
The idea that marijuana can be helpful in treating glaucoma dates to the 1970s. Studies conducted then showed that smoking marijuana lowered the IOP of people with glaucoma. As a result of this research, additional studies were conducted examining whether marijuana or its active ingredient, a compound known as THC, could be used to keep IOP lowered. This research was supported by the National Eye Institute, a division of the federal National Institutes of Health.
The research found that when marijuana is smoked or when a form of its active ingredient is taken as a pill or by injection, it does lower IOP. However, it only lowers IOP for a short period of time—about three or four hours.