Cannabis for glaucoma: a history of medicine and activism

Few people know that the modern history of medical cannabis began with a 26-year-old American with glaucoma who noticed that smoking cannabis improved the symptoms of his disease. This was Robert C. Randall, who won his case in court and became the first “official” medical cannabis patient. As a result, research into the medicinal properties of THC began in the 1970s.

To mark World Glaucoma Day, on the Cannactiva blog we talk about the history and effectiveness of the use of cannabis in the treatment of glaucoma, with Dr Fabio Turco and Viola Brugnatelli, from Cannabiscientia.

What is glaucoma?

Glaucomas are a group of eye disorders characterised by progressive damage to the optic nerve, often associated with increased intraocular pressure (IOP), leading to irreversible vision loss. Glaucoma may develop slowly, and the gradual loss of vision may go unnoticed for a long time. Regular eye examinations, including pressure measurement and peripheral vision testing, are essential for people at risk of developing glaucoma.

Glaucoma affects nearly 64 million people worldwide, ranking as the second most common cause of blindness globally. It is particularly prevalent among people over the age of 60, with only half of those affected aware of their condition.

Treatment

The onset of glaucoma is often associated with elevated intraocular pressure, something first described in 1622 by the English physician Richard Banister, who stated: “the eye becomes firmer and harder than it should be by nature”.

Treatments for glaucoma focus on medicines that reduce intraocular pressure, such as pilocarpine, beta blockers (timolol), alpha agonists (brimonidine), prostaglandin F2α analogues (latanoprost) and carbonic anhydrase inhibitors (dorzolamide). When medicines are not enough, surgical options are considered viable. Despite these treatments, the search for more effective and better-tolerated options continues today.

Cannabis use for glaucoma: a history of activism

To explore the efficacy of medical cannabis for glaucoma, we embarked on a journey through the pages of Cannabiscientia's Principles of Cannabinology Handbook, by Viola Brugnatelli and Fabio Turco. This handbook serves as a guide for European healthcare professionals and enthusiasts seeking an in-depth understanding of the medical applications of cannabis.

Cannabis and cannabinoid-based medicines came into use in the 1970s, and since then cannabis has achieved almost mythical status as a miracle drug for glaucoma. It was then, because of glaucoma, that the modern history of medical cannabis began in 1974.

The Robert Randall case

In the 1970s, Robert C. Randall, a 26-year-old glaucoma patient, discovered that smoking cannabis relieved the symptoms of his disease. Randall faced federal charges for growing cannabis, but successfully defended himself on the grounds of medical necessity. In 1976 the judge ruled in his favour, and he became the first “legal” user of medical cannabis.

Randall's defence led to the Marijuana Research Project, the first government-run medical cannabis cultivation programme in the US, which supplied cannabis to patients until 1992. Randall was a leading activist for cannabis legalisation, founded the Alliance for Cannabis Therapeutics and sued the federal government when it tried to stop giving him access to medical cannabis. This lawsuit and the subsequent ruling set an important precedent by legitimising the medical use of cannabis, helping other patients gain legal access to medical cannabis. The ruling also strengthened the efforts of Randall and other activists to promote laws recognising the medical benefits of cannabis in several states.

The 1988 ruling was ignored by the DEA (Drug Enforcement Administration), which continued to maintain a restrictive stance on cannabis despite the legal victories recognising its medicinal use. In the years that followed, there were many attempts to reclassify cannabis and recognise its medical value, but the DEA consistently rejected them.

In 1988 the DEA was forced to hold hearings on rescheduling cannabis, pushed by Randall and other activists. The DEA's administrative law judge, Francis Young, urged that cannabis be moved out of its drug schedule, stating that “cannabis is one of the safest therapeutically active substances known to man”. However, the DEA rejected the ruling and decided to keep cannabis as a Schedule I substance, stating that it had no accepted medical use and a high potential for abuse. Today we can say that, almost half a century later, in 2024 the United States announced the reclassification of cannabis to remove it from Schedule I of controlled substances.

Randall died in 2001, and his legacy includes his valuable contributions to the medical cannabis movement.

History of drug prohibition

Cannabis and cannabinoids in glaucoma: current research

Mechanism of action

Cannabis and cannabinoids are effective in the treatment of glaucoma in the following ways:

• Some cannabinoids reduce intraocular pressure by interacting with the endocannabinoid system of the eyes, on CB1 receptors.
• They modulate prostanoid synthesis through the cyclooxygenase (COX) pathway, influencing various structures of the eye.
• In addition, some cannabinoids have a neuroprotective effect, protecting retinal ganglion cells by inhibiting the release of glutamate, endothelin-1 and nitric oxide.

Clinical experience in personalised therapy for glaucoma patients: a prescriber's considerations

Dr Lorenzo Calvi, an Italian anaesthetist and ethnopharmacologist, challenges the belief that cannabis is not a good treatment for glaucoma, based on his practical experience of treating approximately 150 glaucoma patients. He claims an exceptional success rate of 98%, emphasising the minimal amount of cannabinoids needed and the absence of psychotropic side effects.

According to Dr Calvi, cannabis for glaucoma can be taken orally, although the best results are obtained with eye drops. Microemulsions or cyclodextrins are used to prepare the eye drops, which minimise the problem of the poor water solubility of cannabinoids. Glaucoma treatment is always long-term, so side effects must always be monitored, especially if THC is used.

Dr Calvi stresses the importance of personalised therapy tailored to each patient, respecting the natural synergy between cannabinoids and terpenes for an effective and clinically safe outcome. He suggests that the positive results seen in the treatment of glaucoma with cannabis may be applicable to other diseases, and advocates a collaborative effort between doctors, patients and pharmacists to ensure the success of cannabinoid therapies.

Cannabis and glaucoma: conclusions

While the medical cannabis movement was born out of the effectiveness of cannabis in managing the symptoms of glaucoma, it is not currently considered a first-line therapeutic option because of its limitations and side effects.

Although cannabinoid medicines may be a useful alternative for some patients with glaucoma that is resistant to conventional treatments, their use is limited by several factors. The short duration of their effect, the need for multiple daily doses and the side effects restrict the long-term efficacy and safety of medical cannabis. Conventional treatments, such as eye drops and surgery, remain the most effective and safest options for most glaucoma patients.

The information in this article is taken from Cannabiscientia's Principles of Cannabinology Handbook, by Viola Brugnatelli and Fabio Turco and Prohibition Partners. It is a guide to medical cannabis and cannabinoids for healthcare professionals that covers the European medical cannabis landscape in depth. The second edition is now available. Visit Cannabiscientia for more information.

Note: This is an informational article and is not intended to prevent, diagnose or treat any disease. Its content may complement, but should never replace, the diagnosis or treatment of any disease or symptom. Cannactiva products are not medicines and are intended for external use. There may be relevant new scientific evidence since the date of publication. Consult your doctor before using CBD. The therapeutic approach must always be personalised and depends on professional assessment.