It has long been known that use of cannabis positively affects eye function. Some of the first modern medical activists for reform included those with glaucoma – a condition that causes damage to the optic nerve. Evidence also now seems to suggest that cannabis also may positively affect the night vision of those who use it – with implications that cannabinoids may improve overall visual acuity.
One of the earliest studies on the same came out of the University of the West Indies. A pharmacologist noted that fishermen who either smoked cannabis or drank rum infused with leaves of the plant had “an uncanny ability to see in the dark”. Researchers in Morocco using a scotopic sensitivity tester – a machine that tests for the development of glaucoma, also found that both synthetic and natural THC seemed to improve the night vision of their test subjects.
A recent study found evidence that cannabis can help increase nighttime eyesight by upping our light sensitivity. That’s right, you may be able to improve your night vision with cannabis! How awesome is that?
It has been common knowledge since the discovery of the endocannabinoid system, that marijuana works by stimulating both CB1 and CB2 receptors found throughout the body. CB1 receptors are primarily found in the brain and nervous system.
However, what is interesting about this latest study is that it seems to fundamentally refute earlier hypotheses about why cannabis acts the way it does to improve vision overall – not just at night or in low light situations. Investigators in the West Indies hypothesized that cannabis, since its use dilated the pupils, it also allowed more light to fall on the retina. Researchers also theorized, that stimulation of the CB1 receptor, which is found deeper in the head, than the visual cortex, might be responsible for such improvements. This new study seems to quantify this second theory. By applying cannabinoids to the eye tissue of African toads, researchers found, that cannabis appears to stimulate the actions of retinal ganglion cells – making them more sensitive to light by inhibiting a protein called NKCC1 via the CB1 receptor.
NKCC1 is a transporter protein that moves sodium, potassium and chloride ions in and out of cells and in doing so, determines the electrical properties of nerve cells.
What these latest studies seem to indicate, is that cannabinoids make such cells more “excitable” and therefore more sensitive to light.
Researchers at McGill University in Montreal applied a synthetic cannabinoid to the eye tissue of the African toad. They found that the toad was more receptive to light and was able to respond to it faster. To take it a step further, they tested this theory on tadpoles. By using dark dots, which tadpoles naturally avoid, they were able to determine that those given the synthetic cannabinoid were better able to perceive the differences in these dots in the dark and were able to avoid the dots better than their tadpole counterparts who were not given the cannabinoid.
This provides some corresponding scientific truth to the anecdotal reports that cannabis does increase our eyes light sensitivity. Not only that, cannabis has been found to have neuroprotective-effect on retinal cells, meaning it can help protect our eyesight. This is especially helpful for individuals who are experiencing a decline in sight due to age.
CANNABIS DECELERATES VISION LOSS
It has been known for quite some time, that use of cannabis can significantly slow down the progression of eye conditions leading to blindness and has overall neuroprotective effects. Researchers at the University of Spain conducted tests on rats with retinitis pigmentosa (a degenerative eye disease). After 90 days, the rats who were treated with cannabinoids had better results in vision tests and actually acquired 40% more photoreceptors than the rats that had not been treated with the drug. This is in line with other research that also confirms that cannabis actually causes cell growth in the brain – a process called neurogenesis.
CANNABIS IMPROVES VISUAL PROCESSING
Researchers at the University of Waterloo in Ontario also found evidence, that babies exposed to cannabis in the womb also seem to have better vision – specifically in their ability to track moving objects. Research showed, that exposure to marijuana in the womb improved global motion perception – a processing function within the brain’s dorsal visual pathway. The children who were studied were all born to mothers who had used nicotine, other drugs like methylamphetamine or alcohol during pregnancy. In direct contrast, fetuses exposed to alcohol showed a negative effect, while nicotine and methamphetamine seemed to have no effect. Despite this of course, scientists in this study were quick to warn, that marijuana does not have an overall positive effect on prenatal development.
CANNABIS SEEMS TO IMPROVE OVERALL VISION
What the research clearly does indicate, no matter how inconclusive at this point, is that cannabis seems to improve vision in several different ways by stimulating the CB1 receptor. This effect has been noticed by both those with eye diseases and those without. As a result, the promise of cannabis for treating a large range of eye diseases seems highly promising.
THC acts within the brain to enhance the natural stimulation of vision in low light situations created by a naturally occurring endocannabinoid within the body called anandamide – the so-called “bliss molecule” also responsible for creating the “runner’s high”.
So, next time you’re going out into the dark, try hitting a bowl, take an edible treat or spark up a joint. Not only will you get a little taste of what it’s like to have superpowers, you’ll be doing your retinal cells a service.
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