Using Botulinum Toxin A for Chronic Ocular Pain
Pain anywhere can be an issue that leaves people feeling that their quality of life has diminished. Some people experience chronic pain in their eyes, which can lead to additional problems. Having been impacted by pain presents a challenge for those who experience ocular pain, often leaving them unsure of what to do to find relief. A new study looked at whether or not using botulinum toxin A injections could help those suffering from chronic pain.
The outcome of the study is published in the June 2023 issue of the journal Frontiers in Neuroscience (1). The study included 12 people who have chronic ocular pain and light sensitivity. All the people were recruited from a veteran’s healthcare setting and had been experiencing ocular pain for at least one week. They also had to have photophobia in order to be included in the study.
Study participants underwent an examination before the study began and 4-6 weeks after receiving treatment with the injections. The examination included an ocular surface examination using an fMRI design. Participants evaluated the light unpleasantness that they experienced after they had each scan. They also conducted and analyzed a whole brain blood oxygen level-dependent response to the light stimuli.
When the study began, all participants reported unpleasantness with the light stimulation. The injections were administered at seven sites in the forehead. After they had received the injections for 4-6 weeks, the unpleasantness scores all went down, but there was not a significant decrease. They report that half of the people who participated in the study reported that there was a decrease in the unpleasantness of the light stimulus. In contrast, three reported an increase, and three reported no change.
The injections did help some people have a decrease in unpleasantness, but it did not help everyone in the study. The researchers conclude that it may benefit some people and that the injections may have enhanced efficacy for those with higher light-evoked activity in the trigeminal nerve before the treatment.
According to the American Migraine Foundation, photophobia is a common migraine symptom (2). The condition is extreme light sensitivity and is one of the criteria that is used to diagnose migraines, although people can have photophobia and not experience migraines. Those with the condition may feel that things are too bright or that pain is associated with the light. While everyone has some level of light sensitivity, those with photophobia feel pain and discomfort when exposed to a lot of light or need to adjust from a dark to a light condition.
Sources:
- Frontiers in Neuroscience. Botulinum toxin A decreases neural activity in pain-related brain regions in individuals with chronic ocular pain and photophobia. June 2023. https://pubmed.ncbi.nlm.nih.gov/37404468/
- American Migraine Foundation. What is photophobia, and Can it Be Treated? https://americanmigrainefoundation.org/resource-library/what-is-photophobia/
