The Endocannabinoid System: Role in Ocular Physiology and Therapeutic Potential in Eye Diseases: A Narrative Review.

The endocannabinoid system (ECS) is a multicomponent signaling network that controls several physiological processes, including neurological, immune, cardiovascular, digestive, and ocular functions. The components of ECS (i.e., receptors, ligands, metabolizing enzymes, and carriers) are expressed in eye structures and neurological areas involved in the visual process. Experimental evidence supports ECS involvement in ocular pathophysiology. Preclinical and clinical studies indicate that cannabinoids (CBs) lower intraocular pressure and exert vasoactive, anti-inflammatory, and protective effects in the retina and ocular surface. However, CBs elicit modest and transient effects while inducing tolerance, dependence, and adverse effects, which prevent their use in ophthalmic clinics. This review summarizes experimental and clinical data on the role of ECS in ocular pathophysiology. It also reports research on the therapeutic potential of CBs in common eye disorders. Lastly, it highlights promising alternative strategies for modulating ECS and improving ocular drug delivery to improve therapeutic efficiency in ophthalmic clinics.