Glaucoma is a condition of the eye that is associated with increased pressure within the eye which causes damage to the optic nerve. Increasing evidence suggests glaucoma is connected to neurodegenerative disease. This leads to: loss of vision, appearance of rainbow colours, circles around bright lights, eye pain, headaches, nausea and vomiting.
Various studies have shown that cannabis does indeed decrease the pressure within the eye that causes damage to the nerve.
Specifically, the active ingredient THC and its anti-inflammatory properties lead to the drop in intra-ocular pressure (IOP), however, for only a short amount of time when smoked or administered directly into the eye. In some patients, it has slowed and even stopped the loss of vision. It helps with alleviating pain and nausea associated with headaches from pressure within the eyes.
In the early stages of glaucoma, some studies have shown mixed results. This could be due to the difficulty of gauging consistent dosage when symptoms are weak and/or transient. However, with later stages of glaucoma, cannabis has been shown to be quite effective at reducing IOP and alleviating the accompanying symptoms.
The most direct method of intake is through topical eye drops of 2.8% THC drops. This method directly lowers the IOP which is the leading cause of nerve damage in the eye; however, these drops are difficult to source. Other options include smoking or vaping which are fast-acting but also short-term. Cannabis should be administered about 4 times per day to ensure that that IOP stays low.