THC in marijuana relieves intraocular pressure, thereby reducing damage to the optic nerve, and reduces blood flow to the optic nerve which can have negative effects. THC also relieves symptoms like eye pain, headaches, nausea and vomiting.
Glaucoma is an umbrella term for a group of progressive eye conditions characterized by damage to the optic nerve. Increased intraocular pressure (IOP), or pressure inside the eye which damages the optic nerve, is typical of the two most common forms. The optic nerve is vital in order to send visual information to the brain, and that route is interrupted when it is damaged.
Symptoms of glaucoma include headaches, eye pain, nausea and blurred vision while patients slowly lose their field of vision over time.
Only about half of the people suffering from glaucoma even know that they have it but it is the second leading cause of blindness in the world. The Glaucoma Research Foundation estimates that 60 million people suffer from glaucoma in the world – 2.7 million of them in the U.S. alone.
Medical marijuana has long been known to lower the intra-ocular pressure that causes glaucoma, but it also helps by treating related symptoms like pain and nausea.