(Cannabidiol (CBD) and Diabetic Retinopathy) "Drugs that enhance extracellular adenosine signaling have been of clinical interest in treatment of inflammation after myocardial or cerebral ischemia.25,26 CBD as an anti-inflammatory drug is an attractive alternative to smoking marijuana because of its lack of psychoactive effects.27 CBD is known to be nontoxic in humans,28 which has previously been a problem for other nucleoside inhibitor drugs.29,30"

Source

Liou, Gregory I.; Auchampach, John A.; Hillard, Cecilia J.; Zhu, Gu; Yousufzai, Bilal; Salman, Mian; Khan, Sohail; and Khalifa, Yousuf, "Mediation of Cannabidiol Anti-inflammation in the Retina by Equilibrative Nucleoside Transporter and A2A Adenosine Receptor," Investigative Ophthalmology & Visual Science (Rockville, MD: Association for Research in Vision and Ophthalmology, December 2008), Vol. 49, No. 12, p. 5531.
http://www.iovs.org/cgi/repri…