Last Updated on 21 June 2024
Can marijuana cure glaucoma? That is the most frequent question asked by patients harmed by this disease. Glaucoma, in fact, is an eye condition that affects 55 million people all over the world, according to the World Health Organization.
In this article, I explored the pros and cons of marijuana to treat glaucoma. Keep reading to discover more.
Glaucoma: What is It?
Glaucoma is a disease which affects the eyes and is the main cause of permanent vision loss. It occurs when intraocular pressure (IOP) increases and progressively damages the optic nerve, namely the organ which transmits the signals of vision to the brain, returning them to the retina.
Intraocular pressure depends on the aqueous humor, transparent fluid you find in the ocular globe. If this fluid increases abruptly, you can experience angle-closure glaucoma. If it increases slowly, instead, you’ll have open-closure glaucoma. The latter is the most widespread one.
The causes of the disease can be genetic, but also linked to other particular conditions, such as diabetes, previous eye disorders, such as high myopia and cataracts, aging and traumas.
In reality, these triggers give rise to different types of glaucoma. In every case, the disease narrows the vision, up to definitely destroying it.
In this sense, we can consider glaucoma as a progressive and degenerative disease that needs to be stopped before causing the awful and tragic blindness.
More treatments and solutions have been put into place to cure glaucoma, from eye drops to surgery, until experiments with stem cells used to rebuild human eyes, but none of them has turned to be a permanent cure, so far.
That is the main reason which pushes us to wonder if marijuana or cannabis may be helpful to treat glaucoma and prevent cecity. Let’s explore the matter further.
Properties of Marijuana
Marijuana, also called cannabis, is a genus of plants producing compounds named cannabinoids. The main families of cannabis are the genus sativa, indica and ruderalis. However, the most common is cannabis sativa.
The active compounds are extracted from the leaves, which, in turn, contain a fiber called hemp.
Cannabis contains over 400 chemicals, but only the ones formed by carbon, hydrogen and oxygen, known as cannabinoids, have relevant effects on human health.
Among them, only two are particularly interesting. These are THC and CBD (cannabidiol). Both of them have psychoactive effects. While THC is a psychotic agent which can give addiction, CBD has milder psychoactive effects which may be helpful to reduce anxiety.
Besides these well-known properties, cannabis has other therapeutic effects which are helpful to treat many medical conditions, such as pain, inflammation, multiple sclerosis, epilepsy, schizophrenia, cardiovascular diseases, cancer, Parkinson and Alzheimer diseases, obesity and glaucoma.
The healthy properties of cannabis are related to the fact that cannabinoids have neuroprotective effects on many tissues and organs, especially the ones depending on nerves and nervous system.
As regards glaucoma, its bad consequences involve just the optic nerve damage. In this case, marijuana may be extremely beneficial to slow and even stop the vision loss.
Healthy Properties of Marijuana: the History
The beneficial properties of marijuana have been known since 1971.
At the time, a 26-year-old man, Robert Randall, affected by severe and neglected glaucoma, noticed that the eye disorders he experienced because of his high IOP (Intraocular pressure), disappeared after smoking cannabis. And so, he started growing it, at home, in Washington, but his plants were discovered during a raid of the police in the nearby apartment.
When he found himself in front of the Court, he affirmed that his severe glaucoma was relieved by the cannabis smoke. Afterwards, he underwent a series of glaucoma tests that confirmed his statement, and so it was, that, in 1976, Robert Randall became the first patient who used cannabis legally for medical reasons. A judge, in his sentence, wrote that “cannabis was one of the most active and safe therapeutic substances known by humans”.
Effectiveness of Marijuana and Cannabinoids for Glaucoma
Marijuana and cannabinoids help relieve glaucoma for two reasons:
- They lower intraocular pressure (IOP): this effect is obtained through the interaction among cannabinoids and the eye receptors present in the retina and the other anterior structures of the eye. This interaction facilitates the lowering of IOP through the regulation and the drainage of aqueous humor in the eyes.
- They work, as said, with a neuroprotectant effect: several studies proved that cannabinoids protect retinal ganglion cells (RGC) from many types of damage.
There are three mechanisms involved in the neuroprotectant function of cannabinoids: inhibition of glutamate, endothelin 1 and production of nitric oxide.
How Cannabinoids Work for Glaucoma
Several clinical trials showed that cannabinoids reduce intraocular pressure and slow the progression of glaucoma.
The cannabinoid which has had the best results is THC (tetrahydrocannabinol). THC works only when it is administered orally, inhaled or through intravenous injection, but not when it is applied locally as an eyedrop.
This drawback occurs because THC is a liposoluble molecule that can’t be dissolved in a water solution.
To solve this problem, scientists are trying new formulations, such as the ones with cyclodextrins, which make THC more soluble.
However, the effects of the other dosage forms last only 3 or 4 hours. Poor benefits and heavy side effects, in fact, didn’t make the usage of THC viable.
THC Side Effects
The main side effects of THC intake are:
- bloodshot eyes
- conjunctival swelling
- pupil dilatation
- light sensitivity or photophobia
- dry eyes
- involuntary movement of the eyes.
To reduce the THC side effects, this cannabinoid is often combined with Cannabidiol (CBD). The latter can also reduce IOP when administered alone, but with irrelevant effects. Moreover, CBD triggers ocular toxicity, as well.
Does Cannabis Treatment Work for Glaucoma?
On that front, the opinions of doctors are fairly controversial.
Dr. Nick Andrew, specialist eye surgeon, on his blog writes that “it seems as if one can develop neurological tolerance to cannabis, and it is likely that one can also develop tolerance to his/her pressure-lowering effect. This would mean that, over time, eye pressure may no longer drop after each exposure to cannabis”.
A scientific revision of medical literature, published in 2020, concluded that, currently, there is no clear evidence on the benefits and effectiveness of marijuana for glaucoma.
An Italian doctor, Lorenzo Calvi, surgeon and the utmost expert in medical treatments with cannabis, instead, disagrees with this conclusion.
In an interview, Calvi affirmed that he cured 150 patients with glaucoma through cannabinoids and apart from 2 unlucky persons, the results have been outstanding in 98% of the cases.
He also specified that the quantity of the drug is so low that there is no risk of psychotic effects. However, Calvi also suggested that the therapy must be customized upon the needs of every patient. “Everything – he said – must be done, respecting the original properties of the plant, which with the natural synergy between cannabinoids and terpenes allow us to obtain an effective, powerful, clinically safe low-dosage medication”.
Other Effective Compounds for Glaucoma
Further trials suggest the usage of other types of cannabinoids, such as Cannabigerol (CBG), extracted straight from hemp. This psychoactive compound reduces intraocular pressure (IOP) without toxicity.
Another natural, helpful substance for glaucoma is palmitoylethanolamide (PEA). Studies revealed that the compound protects the retina, reduces IOP, intraocular dilatation, and has no side effects.
Conclusion
As you can see, the usage of cannabis for glaucoma is still controversial, but not for a long time.
I have my best friend affected by glaucoma, and, one day, on the phone, he said to me: “I don’t deserve to lose my vision, I never hurt anyone in my lifetime”. I replied that problems don’t last forever, what is not curable today, may be cured tomorrow.
I am absolutely sure about that.
Many doctors are sure that not invasive surgery and new cannabis formulations, such as eye drops and pills without toxicity or side effects are the main road to heal glaucoma and get your vision back.
This is my best wish for my friend and all those who are struggling with this eye condition.
References and Bibliography
- National Eye Institute – Types of Glaucoma – www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucoma/types-glaucoma
- Dr Nick Andrew. Ophthalmologist, Specialist Eye Surgeon – Marijuana as an alternative treatment for glaucoma – https://drnickandrew.com.au/glaucoma/glaucoma-treatment-glaucoma/medical-cannabis-as-treatment-for-glaucoma/
- SICAM – Glaucoma e Cannabis – Review e Studi dal 1971 al 2016 – https://sicamweb.it/glaucoma-e-cannabis/
- Kaur R, Ambwani SR, Singh S. Endocannabinoid System: A Multi-Facet Therapeutic Target. Curr Clin Pharmacol. 2016;11(2):110-7. doi: 10.2174/1574884711666160418105339. PMID: 27086601. https://pubmed.ncbi.nlm.nih.gov/27086601/
- Cannabis Scienza – Cannabis e glaucoma: una storia di attivismo e terapia – https://cannabiscienza.it/pubblicazioni/patologie/cannabis-e-glaucoma/
- Dr Lorenzo Calvi, surgeon and expert in treatments with Cannabis sativa – https://www.cannabis-medicinale.com/
- Keppel Hesselink, J. M., Costagliola, C., Fakhry, J., & Kopsky, D. J. (2015). Palmitoylethanolamide, a Natural Retinoprotectant: Its Putative Relevance for the Treatment of Glaucoma and Diabetic Retinopathy. Journal of ophthalmology, 2015, 430596. https://doi.org/10.1155/2015/430596
