The human eye is a small but incredibly complex organ that controls vision. The human eye interacts with the endocannabinoid system in a variety of ways, and clinical endocannabinoid deficiency (CECD) can affect several common ocular diseases, including glaucoma, uveitis, macular degeneration and diabetic retinopathy.

​

Diseases of the ophthalmological system are directly affected by the endocannabinoid system. The eye is particularly vulnerable to diseases linked to oxidative stress such as glaucoma, uveitis, macular degeneration and diabetic retinopathy. Studies have unmasked the effects of cannabinoid (CB) receptors expressed in the eye and are currently exploring how to utilize phytocannabinoids like CBD and THC to treat ocular disorders. 

​

Healthcare professionals incorporating Cannabis into their medical practice, whether prescribing medical marijuana or CBD derived from hemp, are reassured by the many potential theoretical mechanistic pathways by which Cannabis has shown possibilities for benefit in basic science research as a potentially effective adjunctive treatment option. These include analgesic, antiemetic, antispasmodic, anti-inflammatory, antibacterial, relaxant, and anxiolytic properties. 

​

• Glaucoma refers to an array of ocular disorders that are associated with a pressure imbalance with associated loss of retinal ganglion cells, nerve damage and visual loss that may potentially lead to blindness. This condition is either categorized as open angle, which involves a slow onset and progression of this disease, or closed angle, which involves a painful and rapid progression of the disease. The definition of open or closed angle is related to the width of the angle between the iris and the cornea, through which fluid flows as part of the trabecular network. In an excitingly promising correlation, research suggests CBD acts as a non-psychoactive antioxidant that reduces the production of reactive oxidative species (ROS); and also acts as a neuroprotective against glutamate induced retinal injury, preventing the formation of lipid-peroxides, nitrite & nitrate compounds and nitrotyrosine, which forms the physiological basis for the development of glaucoma.  In addition, research suggests that delta-9-THC decreases the intraocular pressure and reduces retinal ganglion cell death caused by glaucoma.

​

•  Uveitis refers to a group of inflammatory ocular diseases which produce edema or swelling caused by excessive fluid and tissue destruction leading to vision loss and blindness. Uveitis primarily affects the uvula, which is the middle layer of the wall of the eye, comprised of the choroid, cilliary body and the iris. Other components of the eye are common targets of uveitis as well, including the lens, retina, optic nerve and vitreous humor (the clear, gel-like substance that fills the space between the lens and the retina of the eye. According to research, all four types of uveitis may benefit from the anti-inflammatory effects of CBD after their occurrence. CBD is also being studied for its potential to block oxidative stress and the damaging effects of endotoxins. Delta-9-THC may also be helpful in the management of uveitis as it has the potential to reduce inflammation in the retina, vitreous humor and optic nerve. 

​

• There are two forms of age related macular degeneration that are associated with vision loss in individuals over the age of 60. The dry form causes distortion of vision through the deposits of drusen or yellow matter in the macula. The wet form, which is categorized by the growth of abnormal, fragile blood vessels underneath the macula. Researchers are studying how THC and CBD could provide effective neuroprotective and anti-inflammatory properties in ocular disorders. 

​

• Diabetic retinopathy is associated with the deterioration of the blood retinal barrier, a physiological barrier in the eye that regulates the flow of substances into and out of the retina; and the death of retinal ganglion cells culminate in vision loss. CBD research is underway to test its effectiveness in reducing oxidative and nitrative stress in diabetic retinitis based on the cannabinoid potential to reduce inflammation and provide neuronal protection. Additionally, on going research indicates that delta-9-THC may have the potential to regulate the immune system's response to diabetic retinopathy, which could reduce the severity of the disease.

​​​

​