DESCRIPTION (Applicant's Description): Under conditions of glaucoma, the cells of the retina begin to die, leading to progressive vision loss. This cell death may be due to a pressure-induced, excessive release of the neurotransmitter glutamate. While glutamate is a neurotransmitter normally used by retinal neurons, when it is present at high levels for a prolonged period of time, it is toxic to the cells, causing their death. The objectives of this study are to 1) Localize the source of excess glutamate, 2) Determine whether the amount of glutamate measured will lead to retinal cell death, and 3) Evaluate cannabinoids as possible drugs to prevent the retinal cell death.