A homemade cannabis tea, stirred into a small cup of rum, gave Jamaican fisherman unbelievable night sight, creating the first known link between marijuana and glaucoma.
The phenomenon was first observed 27 years ago by Pharmacology Professor Manley West and ophthalmologist Dr. Albert Lockhart, who later developed a cannabis-based eye drop called Canasol.
Professor West was amazed after experiencing a somewhat harrowing evening-water-crossing in an open boat with no lighting or compass to guide the way through coral reefs in shallow water.
In a letter to the publication Nature, he wrote that at day break “it was impossible to believe that anyone could navigate a boat … in such treacherous surroundings.”
Prior to embarking on the journey, the Jamaican fishermen had consumed an alcoholic extraction of mainly the green stems and leaves of the cannabis plant.
“I was then convinced that the men who had taken the rum extract of cannabis had far better vision that I had, and that a subjective effect was not possible.”
Professor West had also observed that villagers used an eye wash made up of “ganja” in water, which they said made them see better.
Dr. Lockhart noted that his Rastafarian patients who used ganja had
a low incidence of glaucoma.
Several years of (mostly unfunded) work was undertaken in a West Indies laboratory, where they discovered that lowering inter-ocular pressure is related to cannabis use.
Dr. Lockhart later discovered that the optic nerve, which causes us to see, was protected by Cansol, and that the eye drops could help prevent blindness.
Later research showed that a specific dose of THC (as Marinol®) improved the night vision of Moroccan men who had been smoking kif for many years.