In the days before marijuana became mainstream, many lived in fear of our usage being detected.
What if you ran into someone you knew? How could you act normal and hide your consumption from parents, cops, significant others, landlords, or nosy neighbors?
While you might have been able to stifle the giggles or dust off the Cheeto crumbs, your red, bloodshot eyes were a dead giveaway.
Today, red eyes are still a problem and science hasn’t found any newer methods to prevent them.
“Not that I’m aware of,” wrote Dr. Rory T. Allar, MD, in an email. Allar is an ophthalmologist with fellowship training in glaucoma at Spokane Eye Clinic.
Whether you smoke, eat, vape, or dab cannabis, it’s generally going to make your eyes red to some degree. Red eye is actually caused by processes happening inside your body vs. anything external, so even if you use items that claim to reduce these visible effects, they are only temporary.
“While over-the-counter eye drops that ‘get the red out’ work for a while to make the eyes look less red, chronic use of drops actually will cause the eye to be more red and irritated long term,” Allar said. “Therefore, I do not recommend these drops.”
What about organic treatments? Some claim that food containing large amounts of caffeine, chocolate or salt can minimize bloodshot eyes.
“Basically, old wives’ tales,” Allar said.
What is it about pot that causes your eyes to look like you have pulled multiple all-nighters?
The answer is tetrahydrocannabinol, or THC, the main active ingredient in cannabis and the compound that makes your body feel relaxed, including the eyes and blood vessels in them.
“Cannabis dilates the small blood vessels on the surface of the eye,” said Allar. “It relaxes them and causes them to be bigger, which causes the eye to look red.”
This dilation is particularly noticeable against the whites of the eye. Some medical professionals believe that marijuana use lowers blood pressure in general, which leads to the expansion of the vessels in the eyes. Over time, there is concern that this could cause eventual health issues, but Allar says he hasn’t encountered this.
“I can’t really speak directly about blood pressure issues, but it seems plausible that there would be a drop in blood pressure if dilation of blood vessels occurs,” he said. “As for red eye, it doesn’t cause long term problems to eye health.”
There has also been speculation that weed is a good treatment for glaucoma, an optical health condition caused by pressure in the eye that can lead to decreased eyesight. The thinking is that when blood vessels are dilated from pot, blood flow improves, relieving that pressure.
“First, a drop in blood pressure, by any means, would not help with the treatment of glaucoma, so the direct answer to your question is no. Cannabis has been shown to lower eye pressure (different from blood pressure), but the effect does not last long, which is why cannabis is not a recommended treatment for glaucoma.”
Along with other effects on your body from marijuana use, red eye is temporary. Red eyes generally only last a couple hours, then fades away. The more pot you ingest though, the longer your blood vessels remain expanded and the longer your eyes look red.
If red eye remains for an extended time after consumption, or becomes an issue even when you’re not using, something more could be going on.
“Many different eye diseases can cause the eye to look red,” said Allar. “If someone is concerned about their eyes being red they should talk with their eye care provider.”
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