In the past centuries, hemp extract was used to treat various eye diseases.
Among them is Glaucoma that is characterized by abnormal high intraocular pressure (IOP) that can be advanced to blindness if not well diagnosed and treated.This makes glaucoma an irreversible blinding eye disease that generates progressive retinal ganglion cells (Cairns, Baldridge, & Kelly, 2016). In their research, they suggest the endocannabinoid system has pulled in a considerable amount of attention as a possible way of treating glaucoma, commonly because of the observed IOP; hence the reducing effects seen after administration of the exogenous cannabinoids (Cairns, Baldridge, & Kelly, 2016).
In this case, the presence of the ECS including CB receptors, endocannabinoids like anandamide (AEA) and 2-arachidonoyl-glycerol (2-AG) in the anterior, posterior lobe of the eye and retina signals the CBS receptors. In effect, cannabinoids in the eye will reduce tear production, and regulate the IOP by decreasing it (Cairns, Baldridge, & Kelly, 2016).
Separately, the presence of the CB1 receptors that are expressed in the primary cells of the neural retina. In this case, the hypotensive effect of the cannabinoid on IOP is primarily affected by the presence of CB1 receptor. On the other hand, following the distribution of the endocannabinoids in the retina and considering the functions of the cannabinoids in modulating IOP in neuropsychology, it is quite clear to suggest that cannabis can be used in treating glaucoma.
Additionally, according to the research conducted by Cairns, Baldridge, & Kelly (2016), Δ9-THC and WIN 55,212-2 activate CB1 and CB1, CB1 can lower the IOP attenuated in βAR knockout mice. This can be concluded that CB1 can stamp down the release of the norepinephrine that reduces the IOP. However, CB2 has little effect in regulating and controlling glaucoma in the sense that they are much sparser in activating IOP.
Looking at the long-term treatment of glaucoma, Cairns, Baldridge, & Kelly (2016) argue that cannabinoids can be used in treating glaucoma and that in chronic, topical application 0.5 percent WIN 55,212-2, was identified in the study to be effective in reducing IOP within few weeks. Conversely, it is evident that CB1has positive characteristics to allosteric modulators that have the capacity of stimulating endocannabinoid-mediated CB1 showing that they lack behavioral side effects and suggest possible use in future treatment of glaucoma.
Other than glaucoma, Mike Membrino and his team have indicated that ECS has been used to regulate other eye disorders. For instance, Cannabinoids are argued to guard against retinal neurotoxicity and have powerful anti-inflammatory agents that protect against degenerative eye diseases. Additionally, CB1 receptor agonist stimulates monoamine oxidase on the bovine retina that stamps down the dopamine release. Phytocannabinoids like THC and CBD have shown the potential to reduce the IOP and protect the retinal blood barrier in diabetic, correspondingly. In conclusion, heightening evidence now suggest that the modulation and correlation of ECS may show potential for management and diagnosis of eye diseases and glaucoma.
Cairns, E. A., Baldridge, W. H., & Kelly, M. E. M. (2016). The Endocannabinoid System as a Therapeutic Target in Glaucoma. Neural Plasticity, 2016, 9364091. http://doi.org/10.1155/2016/9364091