Cannabis Explored as Blepharospasm Treatment

Laird Harrison

November 11, 2021

Cannabis oil may reduce the duration and frequency of spasms caused by benign essential blepharospasm (eye twitching), researchers say.

The treatment could serve as a second-line treatment for patients who have already received botulinum toxin injections, said Ofira Zloto, MD, an oculoplastic surgeon at Sheba Medical Centre in Ramat Gan, Israel.

"We hope it will be encouraging for our patients," she told Medscape Medical News. "These poor patients come every 2 months to get an injection of Botox, which [involves] painful injections all over their eyes and their forehead. And sometimes they don't get any relief from that."

She presented the finding at the American Society of Ophthalmic Plastic & Reconstructive Surgery (ASOPRS) 2021 Fall Scientific Symposium.

Blepharospasm can be disabling. Patients not helped by botulinum toxin injections can try medications such as anticholinergics, but these usually have limited benefits and may come with adverse effects. Surgery is also usually unsuccessful, Zloto said.

Although the cause of benign essential blepharospasm is poorly understood, it falls into the category of dystonia. And cannabis has shown some success in previous trials as a treatment for other kinds of dystonia, Zloto said.

To see if it could work for blepharospasm, she and her colleagues recruited patients who had been treated unsuccessfully with botulinum toxin and were otherwise in good health. They randomly assigned three patients to take cannabis oil drops, and three patients to take a placebo, under their tongues.

The tincture oil drops, the Erez brand made by Tikun Olam, contain 3% tetrahydrocannabinol (THC) and 0.1% cannabidiol (CBD). THC is the component of cannabis that seemed to provide the benefit in other forms of dystonia, Zloto said. The placebo consisted of the vehicle oil without the cannabis.

The researchers gradually increased the cannabis dose for each patient to achieve the optimum effect and tolerability.

During the first 6 weeks, the mean duration of spasm attacks was 4 minutes, 14 seconds in the treatment group and 73 minutes, 54 seconds in the placebo group, a difference that was statistically significant (P < .01).

For another 6 weeks, the researchers provided cannabis oil to both groups. The original treatment group used an average of 6.27 drops and the former placebo group used an average of 5.36 drops, a difference that was not statistically significant (P = .478). There were 61 spasm events in the treatment group and 94 spasm events in the placebo group, which was on the border of statistical significance (P = .05). The mean duration of spasm attack was 1 minute, 46 seconds in the original treatment group and 8 minutes, 57 seconds in the former placebo group, which was significantly different (P < .01).

"When you think about yourself, if you have 60 attacks of spasm, compared to 90 attacks of spasm, it's a lot," Zloto said. These results suggest that the effects from the original 6 weeks continued into the second 6 weeks, she said.

The side effects were mild. For the treatment group they included general fatigue, dry mouth, and insomnia. The placebo group also reported some similar symptoms, Zloto said, and no patients reported experiencing the psychoactive effects associated with recreational use of cannabis.

The researchers are now expanding this pilot study into a multicenter trial that will include hemifacial dystonia as well as blepharospasm.

"Using these drops in conjunction with botulinum toxin seems to give very impressive results," said Michael Yen, MD, an oculoplastic surgeon and professor of ophthalmology at Baylor College of Medicine in Houston, Texas, in an interview with Medscape Medical News. "And so that might alleviate the use of other second- or third-line treatments to give patients better control of their eyelid spasms. There are patients where we probably would eventually move on to doing surgery. If by adding this treatment with cannabis can avoid surgery, I certainly think that can reduce the overall morbidity for these patients."

Yen, who was not involved in the study, cautioned that the trial should be confirmed by others before clinicians can be confident in the findings.

Zloto and Yen have disclosed no relevant financial relationships.

American Society of Ophthalmic Plastic & Reconstructive Surgery (ASOPRS) 2021 Fall Scientific Symposium. Presented November 11, 2021.

Laird Harrison writes about science, health, and culture. His work has appeared in national magazines, in newspapers, on public radio, and on websites. He is at work on a novel about alternate realities in physics. Harrison teaches writing at the Writers Grotto. Visit him at or follow him on Twitter @LairdH


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