An international team of researchers from the United States and Italy evaluated the relationship between plasma THC levels and IOP in a group of healthy adults after self-administration of cannabis cigarettes containing either six percent or 13 percent THC.
Consistent with previous research, inhaling marijuana led to a temporary decrease in IOP. The decrease in IOP was most significant after 60 minutes of smoking but remained below the subjects’ normal baseline for up to four hours. Plasma THC concentrations of 20 ng/mL, but not above this level, were closely associated with a decrease in IOP.
The authors report that “the results of this study suggest that in healthy adults, inhaled THC significantly reduces IOP, and that this effect is related to THC plasma levels.” “IOP decrease occurred soon after inhalation and was reduced by up to 16 percent. …Furthermore, increasing plasma levels up to a concentration of 20 ng/mL was closely associated with an increase in hypotension. Plasma THC levels were not >20 ng/mL associated with a further decrease in IOP.”
Scientists long ago Documented Inhaling THC reduces intraocular pressure. According to what was recently published Scan dataOver a third of glaucoma patients have discussed their medical use of cannabis with their oncologists. (Glaucoma is usually caused by abnormally high pressure inside the eye.) However, the American Glaucoma Association has not endorsed the use of cannabis as a treatment for glaucoma. By contrast, nearly all state medical access laws define glaucoma as a qualifying medical condition.
The full text of the study, “Relationship between plasma tetrahydrocannabinol levels and intraocular pressure in healthy adults” appears in Frontiers in Medicine.