Marijuana can cause different effects on the body, but few have ever imagined that one of them has to do with an increase in visual acuity. A recent study suggests that the controversial plant increases light sensitivity of nerve cells in the retina, improving night vision.
The authors of this study, published in https://elifesciences.org/content/5/e15932 have observed this phenomenon in tadpoles. However, this is not the first time scientists encounter this curious effect of cannabis. About 25 years ago, a pharmacologist at the University of the West Indies (Jamaica) found that a fisherman who consumed the local plant had a visual faculties unusual.
After meeting other similar cases, a group of American and Spanish researchers dug into the phenomenon in 2002. They provided placebo to some of the participants in a trial and cannabis to others, to look after the night vision of the latter had improved, according the results published in here.
The researchers knew that there are more receptors CB1 (which joins one of the psychoactive ingredient of cannabis) in the eye to the brain, so that the key had to be in the retina. However, until now no one knew much more about the underlying biological mechanism.
For this reason, scientists at the Montreal Neurological Institute (Canada) applied to synthetic cannabinoids eye tissue of amphibians and checked by microelectrodes how increased the response of cells of the optic nerve to light. Then they observed that the little animals looked better in the dark by moving away from potential predators.
Cannabinoids reduced concentration of chloride ions into the nerve cells of the retina, making them more excitable and sensitive to light. They not yet know whether the effect is the same in humans or its duration or intensity, but new research corroborating the results could be applied to the treatment of degenerative eye diseases.
