Δ9-Tetrahydrocannabinol and Cannabidiol Differentially Regulate Intraocular Pressure.
Level 5 - mechanism / opinion, no new human data
Preclinical animal model and mechanistic research with no human data.
PubMed 30550613 · doi:10.1167/iovs.18-24838
What was done
Researchers evaluated the effects of topically applied Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on intraocular pressure (IOP) in living mice using tonometry, mRNA expression measurements of cannabinoid receptors, and lipidomic analysis.
What was found
A single topical dose of THC reduced IOP by approximately 28% for 8 hours in male mice via combined CB1 and GPR18 receptor activation. The response was sex-dependent, with stronger effects and higher CB1 and GPR18 mRNA levels in males. CBD exhibited two opposing effects on ocular pressure, antagonized tonic signaling, and prevented THC from lowering IOP.
Why it matters
This study defines the specific receptor pathways (CB1 and GPR18) through which THC lowers IOP and shows that CBD counteracts this therapeutic effect, providing important pharmacological insights for cannabinoid-based ocular therapeutics.
Limits
Conducted entirely in an animal model with no human subjects. The abstract does not report the sample size (n), baseline IOP values, variance measurements, or effects beyond a single topical dose.
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