Use of cannabis does lower the pressure in the anterior chamber of the eye caused by the condition known as glaucoma. The main cannabinoid responsible for this is THC and its derivatives. At this time, there are not any topical (eye drop applications of THC) as the appropriate dosing and safety of this application has not been worked out.
Products such as a concentrated elixirs, extracts, tinctures, or edibles 2-4 times per day may result in lowered pressures; but the product needs to be used consistently and current pharmaceutical options for glaucoma treatment are quite effective.
Inhaled cannabinoids are only active for about 2-3 hours where sublingual and ingested deliveries have longer active effects and would be a better choice for management of eye pressures.
Glaucoma patients should still see there ophthalmologist several times per year to have pressures measured and should be aware of the symptoms of acute glaucoma attacks. Cannabis may not be adequate as single therapy for some glaucoma patients.