Approximately 90 percent of cannabis users say the drug does not impair their vision, but a new study found it does the complete opposite.
A team at the University of Granada determined smoking marijuana alters key visual functions that could deem the person visual impaired and a potential threat when driving.
Visual trials conducted with 31 cannabis users showed, following consumption of the drug, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity significantly worsened.
The findings contradict studies that suggest marijuana use can treat eye diseases like glaucoma.
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Approximately 90 percent of cannabis users say the drug does not impair their vision, but a new study found it does the complete opposite. Left is an image seen as from a person not under the influence and right is after smoking cannabis
Although the recent study was conducted with a small group of participants in Spain, there are others that previously came to a similar conclusion.
For the latest work, 20 males and 11 females ranging from ages 19 to 43 were used – all of which were cannabis users.
The group participated in visual tests when they had not consumed the drug and after smoking it, allowing researchers to see if vision is altered when under the influence.
The results showed that, following consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity significantly worsened.
Visual trials conducted with 31 cannabis users before (baseline) and after (cannabis) smoking marijuana
Despite this, not all subjects reported a worsening of their vision after smoking cannabis.
Indeed, 30 percent reported that their vision had not suffered at all, while 65 percent responded that it had worsened only slightly.
The authors note that the visual parameter that could be most strongly linked to users’ perception of the visual effect is contrast sensitivity.
The study found a negative effect on all of the visual parameters evaluated, with the effect of cannabis on some of the parameters being analyzed for the first time in this research.
These results, together with the lack of awareness that the participants presented about the visual impairment caused by smoking cannabis, indicate the need to carry out awareness-raising campaigns, as this visual deterioration can pose a danger when performing everyday tasks.
The results showed that, following consumption, visual aspects such as visual acuity, contrast sensitivity, three-dimensional vision (stereopsis), the ability to focus, and glare sensitivity significantly worsened
Along with impairing vision, a 2018 study found smoking cannabis or taking medication based on the drug can harm the brain and damage memory
Along with impairing vision, a 2018 study found smoking cannabis or taking medication based on the drug can harm the brain and damage memory.
Trials on mice showed those exposed long-term to cannabinoids – compounds found in the marijuana plant – suffered ‘significant’ memory impairments.
Brain scans confirmed the finding, and showed cannabis can stop vital memory-controlling regions of the organ communicating with each other.
Experts fear both recreational users and those who rely on it to combat their health conditions may be at risk of memory problems.
CANNABIS: THE FACTS
Cannabis is an illegal Class B drug in the UK, meaning possession could result in a five year prison sentence and those who supply the drug face up to 14 years in jail.
However, the drug is widely used for recreational purposes and can make users feel relaxed and happy.
But smoking it can also lead to feelings of panic, anxiety or paranoia.
Scientific studies have shown the drug can alleviate depression, anxiety and stress, but heavy use may worsen depression in the long term by reducing the brain’s ability to let go of bad memories.
It can also contribute to mental health problems among people who already have them, or increase users’ risk of psychosis or schizophrenia, according to research.
Marijuana can be prescribed for medical uses in more than half of US states, where it is used to combat anxiety, aggression and sleeping problems. Researchers are also looking into whether it could help people with autism,eczema or psoriasis.
Cannabis oil containing the psychoactive chemical THC, which is illegal in the UK, is claimed to have cancer-fighting properties, and one 52 year-old woman from Coventry says she recovered from terminal bowel and stomach cancer by taking the drug.
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