CBD’s Side Effects On The Eyes: Are They Anything To Worry About?
CBD

CBD’s Side Effects On The Eyes: Are They Anything To Worry About?

One of the first uses of medical cannabis was to treat glaucoma. That turned out to be a misguided idea.

Decades-old research showed that the THC in marijuana could lower interocular pressure (IOP), and high IOP is one of the issues that leads to or worsens glaucoma. Later research, however, discovered that smoking weed did indeed reduce IOP — but only for a few hours. After that, it returned to its previous level.

The American Academy of Ophthalmology now says that effectively treating glaucoma with cannabis would require extremely high doses of THC, used almost continually. That’s not realistic, even for dedicated stoners.

That brings us to CBD products that are now legal to buy and use. Do they help users with glaucoma or other eye diseases?

Maybe some diseases, but not glaucoma.

A 2022 research review concluded that CBD might provide some benefits for those suffering from many types of eye problems because it appears to work as an antioxidant, anti-inflammatory, and neuroprotective agent.

Preliminary research has shown that those properties might help in treating diabetic retinopathy, corneal pain and inflammation, macular degeneration, infections that cause issues like conjunctivitis, and inflammation that causes problems like blepharitis.

That’s the good news. The bad news is that CBD doesn’t even help glaucoma patients in the short-term way that THC does. Unlike THC, CBD has been shown by various studies to either have no impact on IOP — or increase it even further. In other words, CBD might make glaucoma (and its associated pain and vision issues) worse, not better.

This doesn’t mean that CBD will increase users’ chances of developing the disease, though.

Research indicates that CBD doesn’t cause glaucoma and that users with healthy eyes are at no risk. And while CBD may help patients with other vision-related problems; it’s too early for experts or medical experts to know for sure.

The best approach is to seek advice from an ophthalmologist, primary care doctor, or another healthcare professional. They’re best able to evaluate patients’ health, medical conditions, and the medications they take, and recommend the appropriate course of action.

Let’s dig deeper into the details.

CBD and Its Effects

The first step in this longer discussion is to understand what CBD is and what it does in the body.

CBD and THC

Cannabis and hemp are members of the same plant family, and they each contain more than 100 plant compounds known as cannabinoids. The two most important and best-known are psychoactive THC (tetrahydrocannabinol) and non-intoxicating CBD (cannabidiol).

Users consume THC by using marijuana or other cannabis products; the cannabis plant is loaded with THC and contains very little cannabidiol. The CBD products now legal for sale and use are sourced from hemp, which has high CBD levels and very little THC content.

The two cannabinoids are quite similar in their chemical structures but act differently in the body. That’s why THC gets users high but CBD doesn’t, and it’s why their apparent medical benefits are somewhat different.

Cannabinoids deliver their effects by interacting with an important network of receptors and chemical messengers in the body, the endocannabinoid system (ECS). The ECS oversees an enormous number of crucial functions ranging from thinking and memory to pain, inflammation, and immunity.

The ECS’s messengers are neurotransmitters called endocannabinoids. If the name sounds familiar, it should. Endocannabinoids are almost exactly like cannabinoids, but produced in the body. That similarity allows THC and CBD to interact with ECS receptors the same way that endocannabinoids do — and to send their own control messages (or alter existing ones).

That’s how CBD and THC deliver their effects, but there’s one important difference.

THC binds to one set of receptors (the CB1 receptors) located mostly in the brain and nervous system, allowing it to provide mind-altering effects and affect brain function. CBD interacts with CB2 receptors found throughout the rest of the body, so it has an outsized effect on immunity and inflammation while providing its other apparent benefits.

What are those benefits?

Apparent Effects of CBD

The words “apparent,” “reported,” and “potential” provide cover in descriptions of cannabidiol’s potential medical use. Evidence of the benefits CBD might provide stems from research that’s only preliminary, so regulatory authorities haven’t approved cannabidiol for the prescription treatment of any condition or disease, except for a few rare types of childhood epilepsy.

However, the list of CBD’s apparent benefits keeps growing and becoming more impressive every year. They include:

  • Potentially easing chronic pain triggered by anti-immune and inflammatory diseases like arthritis, gut issues like IBD and IBS, gout, fibromyalgia, asthma, and many more.
  • Apparently helping sufferers with stress, depression, anxiety, and more serious mental health conditions.
  • Potentially relieving insomnia and helping ease other sleep disorders.
  • Apparently slowing the progression of Alzheimer’s, Parkinson’s, and other neurodegenerative degenerative diseases.
  • Potentially reducing heart health risks like high blood pressure and high cholesterol levels.
  • Apparently easing acne and other skin diseases.
  • Potentially reducing or relieving epileptic seizures.
  • Possibly helping the body fight some types of cancer.

That is only a partial list, but many of CBD’s apparent benefits stem from the cannabinoid’s anti-inflammatory, anti-microbial, antioxidant, and immunity-boosting properties that study after study has shown. Most come into play when looking at how cannabidiol might affect users’ vision-related problems.

CBD’s Effects on the Eyes

A lengthy 2022 review of research on cannabidiol’s ocular effects, published in the journal Cellular Physiology and Biochemistry, concluded that CBD might provide substantial benefits for those suffering from eye diseases and vision issues.

The report focused on animal and human studies that compared treatment with cannabidiol to treatment with a placebo, and found that most vision-related issues responded well to CBD. Corneal inflammation, retinal issues caused by bacterial inflammation, and diabetic retinopathy were among the conditions that responded positively.

The authors conceded that some problems limit CBD’s usefulness in treating eye diseases and inflammation. One is that the cannabidiol’s effects generally wear off in just a few hours; another is that the common oral administration method is inefficient and topical application to the eye is difficult. In most studies, less than 5% of the CBD reached the problem sites.

The review concludes that cannabidiol is a promising approach for treating serious eye diseases and conditions, but that more research is needed — particularly on the best ways to effectively deliver CBD to the eyes.

Other research has also supported the potential use of cannabidiol for ocular conditions and explained why CBD might be a good treatment choice.

  • A 2023 research review found that CBD’s apparent immunity-boosting and neuroprotective properties potentially make cannabidiol a valuable weapon in the treatment of diabetic retinopathy, a common complication for long-time diabetics.
  • Studies have found that CBD appears to be a powerful antioxidant. The retinal problems caused by age-related macular degeneration, possibly linked in part to cellular damage caused by free radicals in the body, might be slowed by cannabidiol’s antioxidant effects.
  • CBD is also believed to help relieve pain, and a 2018 study found that the cannabinoid might benefit those with corneal pain and inflammation caused by infections, injuries, dry eyes, surgery, and other issues.
  • Some eye diseases caused by bacteria, including conjunctivitis and blepharitis, could respond well to CBD’s antibacterial and anti-inflammatory properties.

One research conclusion might be surprising to readers who were around in the late 20th century, though. CBD is apparently unable to help glaucoma patients.

Medical marijuana was once touted as an effective treatment for glaucoma, but it turned out that THC didn’t provide the medical benefits that weed proponents believed.

The THC in medical cannabis does briefly relieve the high interocular pressure that leads to the development of glaucoma and may eventually cause vision loss or blindness in patients. The effects are short-acting, however, and IOP returns to previous levels a short time later.

Glaucoma patients would have to consume 18-20 milligrams of THC, six to eight times a day, to provide the desired benefit. Even if that were possible, it’s certainly not ideal. And the results were even less encouraging when CBD was tested as a possible treatment for glaucoma.

Research has found that cannabidiol use doesn’t temporarily lower interocular pressure the way THC does. In some studies, IOP actually increased after administration of CBD, meaning patients were at even more risk of greater pain, greater vision loss, and possible blindness. Cannabidiol is not recommended for those dealing with glaucoma.

All of the evidence is reassuring, however, for those who have normal eyesight. CBD use does not cause or contribute to the development of glaucoma, and it does not cause any other vision-related side effects.

To put it simply, unless you have glaucoma, available research shows that using CBD should not hurt your eyes and may help treat several other types of eye diseases.

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