Glaucoma is characterized by damage to the optic nerve and is considered the second leading cause of blindness in the world. Although several mechanisms of optic nerve damage have not been fully elucidated, the increase in the intraocular pressure (IOP) has been shown to be the main pillar of glaucoma pathology. As a consequence, the most effective treatment approaches of glaucoma entail the use of modalities that lower the IOP, including the use of medications, laser and surgical operations. Despite the great efficacy of the pharmacological treatment, formerly as systemic medications and recently in the form of eye drops, lowering IOP might not be attained in some individuals and some adverse effects would possibly hinder the use of such medications. Given the reported decrease of IOP by marijuana smoking, it has been postulated that its components may represent a therapeutic alternative. The present article demonstrates the possible therapeutic efficacy of marijuana for the treatment of glaucoma.
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Smoked marijuana and glaucoma
It has been widely accepted that marijuana smoking causes a significant lower of IOP in the healthy individuals and glaucoma patients. However, marijuana smoking has been associated with several disadvantages, such as short duration of action (only 3 to 4 hours) which raises the need to smoke marijuana more frequently per day, the accompanying mood-changing effects, and the harmful components in marijuana cigarettes that would damage the lungs, particularly with the prolonged use. In addition, there are multiple chemical substances in marijuana cigarettes that lead to deleterious effects on the brain.
Systemic administration of marijuana components in glaucoma patients
Delivering the active constituents of marijuana to the body in the oral or sublingual forms may help avoid the shortcomings of marijuana smoke. Nonetheless, in a study using tetrahydrocannabinol (THC) in the form of pills for the treatment of glaucoma, the patients experienced some psychotic side effects. Furthermore, hypotension is another serious adverse effect of THC, since lowering blood pressure may exacerbate optic nerve damage by decreasing its blood supply. Therefore, along with the short-time effects of marijuana components, it is imperative to study the performance of marijuana active ingredients over long-periods.
The potential local “eye” impact of marijuana components
Despite the use of THC and other substances of marijuana has been investigated in patients with glaucoma, it was not possible to successfully formulate those substance in the form of commercially-available eye drops to be introduced to the eye. This is because such compounds have low solubility in waters and could not be delivered in effective concentrations to the eye. However, the recent discoveries of specific receptors to marijuana components in the eye provided a considerable need to treat glaucoma through lowering IOP and/or protection of the optic nerve.
Marijuana smoking is not applicable for the treatment of glaucoma since it is associated with multiple adverse effects. Given that the main components of marijuana have the potential to lower IOP, it is important to develop eyedrop formulations based on studying their efficacy and long-term observation of side effects.