Neuroprotective Role of Cannabinoids in Retinal Disease

Cannabinoids, compounds that interact with the endocannabinoid system, have shown promising neuroprotective effects in various neurodegenerative diseases, including those affecting the retina. This review evaluates evidence for the presence and action of cannabinoids in the retina, their function in protecting against oxidative stress and modulating neuroinflammation, and the outcomes observed in animal models of retinal diseases such as glaucoma and age-related macular degeneration (AMD), the most common causes of vision loss. Cannabinoids have proven effective in reducing the neurodegeneration seen in these eye diseases, acting via the CB1 and CB2 cannabinoid receptors. The cannabinoid neuroprotective effect is often of a similar magnitude to the other proven therapy of medical dosage of vitamins, though it confers a greater risk due to neurotoxicity with high THC:CBD ratios, making the vitamin therapy of greater efficacy when time is available. Given the increased ratio of THC:CBD in commercial cannabis strains, rising from 10:1 at the beginning of this century to 100:1 now, the risk of neurotoxicity has increased, reducing the neuroprotective benefit. The proven safety and efficacy of vitamin therapy may be a more viable neuroprotective method than cannabinoid use for chronic conditions, with cannabinoids proving their utility in more acute conditions. This review evaluates both the method of action of cannabinoids and the receptor pathway utilized and compares the suggested therapeutic applicability of cannabinoids with proven vitamin therapy.