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The retina in the back of the eye is responsible for sensing light and sending images to the brain. When it becomes damaged, vision is adversely affected. Studies have shown cannabis has neuroprotective and antioxidant properties to encourage retinal health.
Overview of Retinal Damage
Retinal damage is one of most common ailments of the eyes. The most common causes of retina damage are those related to old age, light damage, or trauma. Each cause may require a different method of treatment, so identifying the cause is especially important. In rare instances, a problem may develop without an obvious trigger, requiring further examination from the specialist.
One of the ways in which retina damage may occur is through a vitamin deficiency. Vitamins A and E are thought to be especially important to that area of the eyes. Making sure there is adequate consumption of those vitamins, either through natural foods or vitamin supplements can help promote eye health. Though the exact reason why these vitamins are so important remains somewhat unclear, it appears as though they are responsible for strengthening some of the pieces that make up the retina.
Light can also damage the retina. Light damage occurs when there is a prolonged exposure directly to intense light. This is why scientists encourage individuals to not look directly at the sun, even during an eclipse.
Another form of light damage can occur with lasers. Laser retina damage is not very common, but it can be a danger. Often, laser pointers, and even grocery checkout scanners, will come with warnings about avoiding looking directly at the laser. Retina burn, as this type of damage is often called, can be painful, especially when it first occurs.
Another form of retina damage may occur when there is direct trauma to the eye. This will likely be from an object hitting or penetrating the eye. When this takes place, the pain is often severe, and will often require immediate medical attention. Even in cases where vision may not be initially affected, it is wise to get the eye checked by an ophthalmologist or other specialist. If there is damage that is not readily apparent, the doctor may discover it upon examination.
Retina damage may also take place as a result of the aging process. Vitamin supplements may help prevent some of this from taking place. Making sure to put as little strain as possible on your eyes is also a good idea. For those who feel they may be having retina problems due to old age, there are a few treatments that can provide some relief. But, it is unlikely any treatment will be able to completely find a cure for geriatric damage.
Degeneration and damage to the retina can also occur as a side effect to diabetes. Diabetic retinopathy causes damage to blood vessels of the light-sensitive tissue of the retina and can develop in anyone with type I or type II diabetes. It can cause temporary or permanent vision problems and is responsible for a large percentage of adult-onset blindness.
Findings: Effects of Cannabis on Retinal Damage
Two major cannabinoids found in cannabis, cannabidiol (CBD) and tetrahydrocannabinol (THC), have demonstrated they offer neuroprotective effects that encourage eye health and prevent vision loss. Research has shown that both cannabinoids function as antioxidants and neuroprotective agents, which allow them increase cell survival within the eyes (Chen, et al., 2005) (Hampson, Grimaldi, Axelrod & Wink, 1998) (Nucci, et al., 2008). One study found that both CBD and THC limit the formation of peroxynitrate, which is responsible for retinal neuron death (El-Remessy, et al., 2003). Another concluded that the neuroprotective effects provided by cannabinoids may help slow the vision loss in the case of degenerative disorders like retinitis pigmentosa (Lax, Esquiva, Altavilla & Cuenca, 2014). Most recently, research has shown cannabinoids to make the cells in the retina more sensitive to light, thus improving low-light vision and once again suggesting that cannabis could be beneficial in the treatment regimens of patients with degenerative eye diseases (Miraucourt, et al., 2016) (Russo, et al., 2004).
Research has also shown that the body’s endocannabinoid system plays a role in the regulation of vasoactivity in the eyes. Numerous studies have demonstrated that CBD and THC are effective at decreasing intraocular pressure, making it beneficial in the efforts toward treating glaucoma (Pinar-Sueiro, Rodriguez-Puertas & Vecino, 2011) (Tormida, et al., 2006) (Liu & Dacus, 1987). An animal study showed that CBD inhibited vasoconstriction of the retina (MacIntyre, et al., 2014). The vasorelaxing effects of CBD and THC reduces pressure in the eyes and therefore the risk of damage (Nucci, et al., 2008).
States That Have Approved Medical Marijuana for Retinal Damage
No states have approved medical marijuana for the treatment of retinal damage. However, in Washington D.C., any condition can be approved for medical marijuana as long as a DC-licensed physician recommends the treatment. In addition, various states will consider allowing medical marijuana to be used for the treatment of retinal damage with the recommendation from a physician. These states include: California (any debilitating illness where the medical use of marijuana has been recommended by a physician), Connecticut (other medical conditions may be approved by the Department of Consumer Protection), Massachusetts (other conditions as determined in writing by a qualifying patient’s physician), Nevada (other conditions subject to approval), Oregon (other conditions subject to approval), Rhode Island (other conditions subject to approval), and Washington (any “terminal or debilitating condition”).
Recent Studies on Cannabis’ Effect on Retinal Damage
Chen, J., Lee, C.-T., Errico, S., Deng, X., Cadet, J. L., & Freed, W. J. (2005). Protective effects of Δ9-tetrahydrocannabinol against N-methyl-D-aspartate-induced AF5 cell death. Brain Research. Molecular Brain Research, 134(2), 215–225. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1824211/.
El-Remessy, A. B., Khalil, I. E., Matragoon, S., Abou-Mohamed, G., Tsai, N.-J., Roon, P., Caldwell, R.B., Caldwell, R.W., Green, K., and Liou, G. I. (2003). Neuroprotective Effect of(−)Δ9-Tetrahydrocannabinol and Cannabidiol in N-Methyl-d-Aspartate-Induced Retinal Neurotoxicity : Involvement of Peroxynitrite. The American Journal of Pathology, 163(5), 1997–2008. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892413/.
Hampson, A. J., Grimaldi, M., Axelrod, J., & Wink, D. (1998). Cannabidiol and (−)Δ9-tetrahydrocannabinol are neuroprotective antioxidants. Proceedings of the National Academy of Sciences of the United States of America, 95(14), 8268–8273. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC20965/.
Lax, P., Esquiva, G., Altavilla, C., and Cuenca, N. (2014, March). Neuroprotective effects of the cannabinoid agonist HU210 on retinal degeneration. Experimental Eye Research, 120, 175-185. Retrieved from http://www.sciencedirect.com/science/article/pii/S0014483514000347.
Liu, J.H., Dacus, A.C. (1987, February). Central nervous system and peripheral mechanisms in ocular hypotensive effect of cannabinoids. Archives of Ophthalmology, 105(2), 245-8. Retrieved from http://jamanetwork.com/journals/jamaophthalmology/article-abstract/636521.
MacIntyre, J., Dong, A., Straiker, A., Zhu, J., Howlett, S.E., Bagher, A., Denovan-Wright, E., Yu, D.Y., and Kelly M.E. (2014, July). Cannabinoid and lipid-mediated vasorelaxation in retinal microvasculature. European Journal of Pharmacology, 735, 105-14. Retrieved from http://www.sciencedirect.com/science/article/pii/S001429991400274X.
Miraucourt, L. S., Tsui, J., Gobert, D., Desjardins, J.-F., Schohl, A., Sild, M., Spratt, P., Castonguay, A., De Koninck, Y., Marsh-Armstrong, N., Wiseman, P.W., and Ruthazer, E. S. (2016). Endocannabinoid signaling enhances visual responses through modulation of intracellular chloride levels in retinal ganglion cells. eLife, 5, e15932. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4987138/.
Nucci, C., Bari, M., Spano, A., Corasaniti, M., Bagetta, G., Maccarrone, M., and Morrone, L.A. (2008). Potential roles of (endo)cannabinoids in the treatment of glaucoma: from intraocular pressure control to neuroprotection. Progress in Brain Research, 173, 451-64. Retrieved from http://www.sciencedirect.com/science/article/pii/S007961230801131X.
Pinar-Sueiro, S., Rodriguez-Puertas, R., and Vecino, E. (2011, January). Cannabinoid applications in glaucoma. Archivos de la Sociedad Espanola de Oftalmologia, 86(1), 16-23. Retrieved from http://www.elsevier.es/ficheros/publicaciones/03656691/addon/S036566911000290X/S300/en/296v86n01a90001302pdf001_2.pdf.
Russo, E.B., Merzouki, A., Mesa, J.M., Frey, K.A., and Bach, P.J. (2004, July). Cannabis improves night vision: a case study of dark adaptometry and scotopic sensitivity in kif smokers of the Rif mountains of northern Morocco. Journal of Ethnopharmacology, 93(1), 99-104. Retrieved from http://www.sciencedirect.com/science/article/pii/S0378874104001503.
Tomida, I., Azuara-Blanco, A., House, H., Flint, M., Pertwell, R.G., and Robson, P.J. (2006, October). Effect of sublingual application of cannabinoids on intraocular pressure: a pilot study. Journal of Glaucoma, 15(5), 3. Retrieved from http://www.ajo.com/article/S0002-9394(07)00148-1/fulltext.