Can cannabis help with glaucoma?
Glaucoma is a common eye condition that often causes optical nerve damage and when left untreated can lead to blindness. In the US, about three million Americans live with glaucoma; globally, the figure is close to 60 million. Glaucoma is recognized as one of the leading causes of irreversible blindness.
Since 1980, surgical procedures and treatments have improved significantly, cutting the risk of developing blindness nearly in half. Nonetheless, while treatment has improved, the number of effective topical drugs remains limited.
Almost universally recognized in medical marijuana states as a qualifying condition, increasing numbers of people have turned to cannabis to help their condition. But is marijuana actually good for glaucoma?
Given the improvement of existing glaucoma treatments, do the benefits of medical cannabis outweigh the potential side effects or risks? Likewise, given the vital role the body’s endocannabinoid system (ECS) plays in disease, what promise does the future hold for developing cannabinoid-derived medications to help with glaucoma?
What causes glaucoma?
Evidence increasingly suggests glaucoma—now widely considered to be a neurodegenerative condition—has a connection to other neurodegenerative diseases like Alzheimer’s disease. Glaucoma appears to be a significant predictor of Alzheimer’s. A precise cause of glaucoma, however, remains a mystery and continues to elude the scientific community.
Current glaucoma treatment options
Because intraocular pressure (IOP) influences the onset and progression of glaucoma, ophthalmologists prescribe treatments that target intraocular pressure. In fact, the only way to prevent vision loss or eventual blindness is to lower IOP levels.
Depending on the severity and progression, ophthalmologists may treat glaucoma with medications such as prescription eye drops, or, if necessary, surgery.
Can marijuana be used for glaucoma treatment?
Going back to the 1970s, studies have shown that cannabinoids can alleviate glaucoma-related symptoms because they lower intraocular pressure (IOP) and have neuroprotective actions. For example, this 1971 study found that ingestion of cannabis lowers IOP by 25-30%.
Despite the findings from early research, few ophthalmologists support the use of medical marijuana for patients with early to mid-stage glaucoma. The main issue ophthalmologists have is that potential adverse effects —particularly when smoking weed—might outweigh short-term benefits. For example, smoking can lead to unstable intraocular pressure, thereby increasing the risk of permanent vision loss.
Further, because its therapeutic effects on glaucoma are short-term, patients would have to consume cannabis frequently—once every three to four hours.
Doctors claim that because glaucoma needs to be treated 24 hours a day, patients would need to consume cannabis six to eight times over the course of a day to achieve consistently lowered IOP levels. Such frequency is hard to maintain and could increase the risk of developing a cannabis use disorder.
However, when it comes to late-stage glaucoma, ophthalmologists are more inclined to embrace cannabis to help with the condition. In later stages of glaucoma, it’s less about directly targeting glaucoma and more about alleviating the accompanying symptoms.
According to ophthalmologist Andrew Bainnson, MD, “We’ve known for some time that medical marijuana is very effective for treating nausea and pain, but not so much for glaucoma. There are some patients with end-stage pain and nausea who may benefit [from medical marijuana], but not from the glaucoma point of view.”
Can cannabis-based treatments play a greater role in the future?
The body’s endocannabinoid system (ECS), is one of our most important physiological systems. Nearly every aspect of our health—including inflammation, immune response, neuroprotection, and pain modulation—are all dependent on the ECS. Given the vital role of the ECS, particularly in neuroprotection and inflammation, cannabinoid-based medications could be immensely useful in treating and preventing glaucoma.
Cannabinoid receptors are prominent in ocular tissues responsible for regulating intraocular pressure. Cannabinoid-derived medications could be developed to serve two roles: lower IOP and protect retinal cells.
Evidence suggests two cannabinoid agonists—WIN55212-2 and anandamide—and several cannabinoids, including CBD and CBG, may be good candidates to develop as therapeutic agents, particularly because even when administered topically (directly to the eye), they are well tolerated.
Challenges with treating glaucoma with cannabis
However, challenges persist: Oral preparations are not good because bioavailability is poor and absorption unpredictable. Inhalation isn’t ideal because effects don’t last long enough.
That leaves topical preparations. But cannabis eye drops—while superior to oral and inhalation administration—do a poor job penetrating intraocular tissues.
The future of medical marijuana and glaucoma
While cannabis, as it is administered today, may not be an ideal treatment for glaucoma, the development of cannabinoid-derived medications represent a promising future direction. And, whether or not cannabis is an ideal glaucoma treatment, there are some people who swear by it as a godsend for their condition, while others consume it as an adjunct to therapy, but not as their primary treatment.
If you or someone you know has successfully used cannabis to treat glaucoma, share your experience with us in the comments section.
This post was originally published on September 22, 2016. It was most recently updated on March 13, 2020.
Glaucoma is a serious eye condition affecting over 3 million Americans. Learn more about marijuana being used as a potential treatment option.
CBD Oil for Glaucoma: How Does It Work?
According to the Glaucoma Research Foundation, an estimated three million Americans suffer from the eye condition and half of them are unaware of their issue. It is the leading cause of blindness in the United States and 10% of people with the condition experience vision loss – even when they get the proper treatment.
In the U.S. alone, glaucoma accounts for up to 12% of all cases of blindness.
It is especially prevalent amongst African-Americans, who are up to eight times more likely to become blind from glaucoma than Caucasians. Despite all of the above, a 2002 Prevent Blindness America Survey uncovered a shocking fact: 30% of people had never heard of glaucoma!
Moreover, 50% of those surveyed had heard of the condition but were unsure of what it was. Let’s try to shed some light on this condition and see whether or not CBD oil for glaucoma may be a long-term treatment option.
What Is Glaucoma?
Also known as the ‘silent thief of sight’, glaucoma is an eye disease that results in elevations in fluid pressure in the eye. If you fail to treat it in time, it can cause loss of vision and even permanent blindness.
In primary glaucoma, the cause is largely unknown. In secondary glaucoma, however, the condition has a known cause, such as diabetes, inflammation, cataract, or a tumor.
Risk factors of glaucoma include:
- Old age
- Illnesses or conditions such as hypothyroidism
- Eye surgery
- Eye injuries
- Ethnic background (African-Americans, Hispanics, and East Asians are at greater risk than Caucasians)
Also, did you know that there are several types of glaucoma?
This type of glaucoma affects up to 95% of people with the condition. Initially, there are no symptoms and it occurs because the drainage canals of the eyes get clogged over time, leading to increased pressure buildup. The intraocular pressure – or IOP, as it’s called – increases because the right amount of fluid cannot properly drain out of the eye.
If you have open-angle glaucoma, the drainage canal entrances are working properly, but there will be a clog deep inside the canals. The condition develops slowly and you may not experience any loss of vision for years. If you can catch it early, medication can help treat the condition.
Also called narrow-angle or acute glaucoma, this condition is relatively rare and involves intraocular pressure that rises rapidly and without warning. The drainage canals become blocked because the iris is not as wide as it is in a healthy eye. The iris’ outer edge bunches up over the canals when the pupil enlarges too fast or too much (such as when you suddenly enter a dark room from a bright outside area).
Symptoms of angle-closure glaucoma include eye pain, nausea, headaches, and blurred vision. You are more likely to notice angle-closure glaucoma than its open-angle equivalent, and in most cases treatment involves surgery to remove some of the outer edges of the iris.
Other Types of Glaucoma
The two glaucoma types we have mentioned above comprise the vast majority of cases. There are however some rare forms of the condition, which include:
- Normal-Tension Glaucoma
- Secondary Glaucoma
- Pseudoexfoliative Glaucoma
- Pigmentary Glaucoma
- Congenital Glaucoma
- Traumatic Glaucoma
- Irido Corneal Endothelial Syndrome (ICE)
- Neovascular Glaucoma
What Are the Most Common Glaucoma Treatments?
Several forms of glaucoma treatment involve surgery in an attempt to fix the issue. When it comes to open-angle glaucoma, eye drops are the most commonly prescribed option.
There are various types of medicated eye drops that are specifically formulated to treat glaucoma, including:
- Cholinergic agents
- Carbonic anhydrase inhibitors
- Prostaglandin Analogues
These medications tend to work in different ways. For example, beta-blockers like Timolol work by decreasing the production of fluid that leads to increased IOP. Prostaglandin analogs, such as Xalatan and Travatan, increase the outflow of fluid from the eye, though these medications come with an array of side effects. For instance, those taking beta-blockers may experience the following:
- Reduced pulse rate
- Low blood pressure
- Shortness of breath
- A decrease in the amount of blood pumped out by the heart
- Decrease in libido
CBD for Glaucoma: Can It Work?
Please note that at the time of writing, there is no permanent cure for glaucoma. Nor have there been any large-scale clinical trials reporting on the specific effects of CBD for glaucoma.
However, a large number of studies have shown cannabis as a whole – even those strains high in THC – to be a viable and highly effective treatment. A 1971 study by Hepler and Frank, for example, discovered that cannabis lowered intraocular pressure (IOP) by up to 30%.
The problem with using cannabis, though, is that you have to consume it every few hours because the effects don’t last very long.
In other words, you have to be high for most of the day. While this might seem like a pleasant way to live for some, it is not practical for most people. Also, while cannabis has a low addiction rate, using it six or more times a day would greatly increase the risk of developing a dependence on the plant.
This is where CBD comes in. Cannabidiol is one of marijuana’s non-intoxicating cannabinoids, and some research has suggested that it is just as useful as THC and other psychoactive compounds for the treatment of glaucoma.
The endocannabinoid system (ECS) was only discovered in 1992, but research since then has uncovered some pretty exciting things. In fact, the ECS has been called ‘the future of medicine’ by some experts.
Glaucoma and the Endocannabinoid System
The ECS is one of the human body’s most important physiological systems. It has an impact on almost every aspect of health, including pain modulation, immune response, and inflammation. Regarding glaucoma, cannabinoid receptors are involved in the ocular tissues which regulate IOP.
Researchers are hoping to create medications from cannabinoids such as CBD that can target these ocular tissues in an effort to reduce IOP and eventually protect retinal cells from the permanent damage that leads to blindness.
Incredibly, there has been evidence for over four decades that CBD could help treat glaucoma. The study, published in the International Journal of Pharmacology and Biopharmacology in 1979, analyzed the effects of CBD on 16 patients with open-angle glaucoma.
After taking CBD, the patients experienced a reduction in blood pressure and an increase in heart rate. Ultimately, this resulted in a decrease in IOP behind the eyes – the direct cause of glaucoma. Moreover, it was observed that the effects of CBD lasted longer in patients with hypertension.
The issue now with existing cannabis-based glaucoma treatment is bioavailability.
Although topical application via eyedrops works best, it still means that only 5% of an administered dose reaches the target.
This is why some people have resorted to vaping CBD (a potent means of administration for glaucoma) or taking it as an oil to ensure that more of the active compound is actually put to use.
It is important to note, though, not to use too much CBD oil as a 2006 study by Tomida et al. found that CBD doses of above 40 mg can actually increase IOP in the eye. In the majority of instances, glaucoma sufferers have found that doses between 10-20 mg have been effective. (Though please note that this is NOT a recommended dosage or valid medical treatment option).
Final Thoughts on CBD for Glaucoma
When administered correctly, CBD could potentially lower IOP and protect the eye’s retinal cells.
Moreover, the vaso-relaxant properties of CBD could increase ocular blood flow and its anti-inflammatory properties have the potential to provide relief not just for glaucoma, but also for other inflammatory eye conditions as well.
One of the biggest problems with existing glaucoma medications (such as those listed above) is the litany of side effects. In most instances, this is far less of an issue when using cannabis. While the THC in marijuana results in a psychoactive ‘high’, CBD is non-intoxicating. Therefore, you can use it regularly, safe in the knowledge that it won’t impact your judgment and side effects are minimal.
According to the Glaucoma Research Foundation, an estimated 3 million Americans have the eye condition . If you are one of them explore CBD.