Smoking marijuana impairs vision by altering key visual functions, research shows

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Smoking marijuana DOES harm vision by altering key functions such as ability to focus and sensitivity to glare, study reveals

  • A study of cannabis users shows that smoking damages eyesight
  • It can change important functions such as three-dimensional vision and focus ability
  • Participants taking the drug also had an increased sensitivity to glare

About 90 percent of cannabis users say the drug doesn’t harm their vision, but a new study found it does the exact opposite.

A team from the University of Granada has found that smoking marijuana alters key visual functions that the person may perceive as visually impaired and a potential threat while driving.

Visual studies conducted with 31 cannabis users showed that after consumption of the drug, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus and the sensitivity to glare significantly deteriorated.

The findings contradict studies suggesting that marijuana use can treat eye diseases such as glaucoma.

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About 90 percent of cannabis users say the drug doesn't harm their vision, but a new study found it does the exact opposite.  Seen on the left is an image of a person who is not intoxicated and on the right after smoking cannabis

About 90 percent of cannabis users say the drug doesn’t harm their vision, but a new study found it does the exact opposite. Seen on the left is an image of a person who is not intoxicated and on the right after smoking cannabis

While the recent study was conducted with a small group of participants in Spain, there are others who previously came to a similar conclusion.

The last work used 20 men and 11 women, ages 19 to 43 – all cannabis users.

The group took part in visual tests when they hadn’t used the drug and after smoking, which allowed researchers to see if vision has changed while under the influence.

The results showed that, after consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus and glare sensitivity were significantly deteriorated.

Visual trials conducted with 31 cannabis users before (baseline) and after (cannabis) smoking marijuana

Visual trials conducted with 31 cannabis users before (baseline) and after (cannabis) smoking marijuana

Despite this, not all subjects reported a deterioration in their vision after smoking cannabis.

Indeed, 30 percent said their vision had not suffered at all, while 65 percent said it had only slightly deteriorated.

The authors note that the visual parameter that can be most strongly linked to users’ perception of the visual effect is contrast sensitivity.

The study found a negative effect on all evaluated visual parameters, with the effect of cannabis on some of the parameters being analyzed for the first time in this study.

These results, together with the lack of awareness presented by the participants about the visual impairment caused by smoking cannabis, indicate the need to conduct awareness campaigns, as this visual deterioration can pose a hazard when performing everyday tasks.

The results showed that, after consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus and glare sensitivity were significantly deteriorated.

The results showed that, after consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus and glare sensitivity were significantly deteriorated.

Along with impaired vision, a 2018 study found that smoking cannabis or taking medications based on the drug can damage the brain and damage memory

Along with impaired vision, a 2018 study found that smoking cannabis or taking medications based on the drug can damage the brain and damage memory

In addition to impaired vision, a 2018 study found that smoking cannabis or taking medications based on the drug can damage the brain and memory.

Tests in mice showed that those exposed to cannabinoids – compounds found in the marijuana plant – for long periods of time suffered ‘significant’ memory impairment.

Brain scans confirmed the finding and showed that cannabis can prevent vital memory-regulating parts of the organ from communicating with each other.

Experts fear that recreational users as well as those who rely on it to combat their health problems are at risk for memory problems.

CANNABIS: THE FACTS

Cannabis is an illegal Class B drug in the UK, which means that possession can result in a five-year prison sentence and those who supply the drug can face up to 14 years in prison.

However, the drug is widely used for recreational purposes and can make users feel relaxed and happy.

But smoking can also lead to feelings of panic, fear or paranoia.

Scientific studies have shown that the drug can relieve depression, anxiety and stress, but heavy use can worsen depression in the long term by decreasing the brain’s ability to release bad memories.

According to research, it can also contribute to mental health problems in people who already have them, or increase users’ risk of psychosis or schizophrenia.

Marijuana can be prescribed for medical use in more than half of the US states, where it is used to combat anxiety, aggression, and trouble sleeping. Researchers are also looking at whether it can help people with autism, eczema or psoriasis.

Cannabis oil containing the psychoactive chemical THC, which is illegal in the UK, is said to have anti-cancer properties, and a 52-year-old woman from Coventry says she recovered from terminal colon and stomach cancer by taking the drug.

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