CORNEA EWAP MARCH 2022 51 do not work in alleviating the pain, it is important to move on.” For peripheral neuropathic pain, Dr. Galor often uses autologous serum tears or biological products. For centralized pain, Dr. Galor uses oral medications that modulate nerves. She noted that these therapies, including gabapentin, pregabalin, and nortriptyline, are used to treat pain elsewhere and have a reasonable side effect profile. In specific cases, she uses adjuvant therapies. She considers botulinum toxin injections and trigeminal neurostimulation in individuals with “migraine-like” eye pain (pain that starts spontaneously and associates with headache and photosensitivity). She has found the periocular injections with bupivacaine and methylprednisolone are often helpful in individuals with postsurgical pain.1,2,3 “We have a lot less data on oral and adjuvant therapies for the treatment of eye pain compared to the treatment of pain elsewhere, so we’re extrapolating what we know about treating neuropathic pain elsewhere in the body and applying this knowledge to eye pain, assuming shared mechanisms,” she explained. Dr. Jacobs said there are many options for modulating peripheral signaling if that’s a component: topical medications, lubrication, plugs, therapeutic contact lenses, botulinum, or nerve blocks. She also mentioned use of systemic agents if there is a central component and noted that multimodal treatment is often required. Are the treatments curative or just palliative for neuropathic pain? Both, Dr. Galor said. “The symptoms are coming from the fact that the nerves are malfunctioning, and these therapies are trying to normalize nerves. However, these treatments are not instantaneous. Normalizing nerve function can take years and a lot of patience on the part of the patient. However, most of my patients slowly get better over months to years if they stick with a treatment plan.” Dr. Galor said she makes sure to tell patients that there is no magic bullet; therapies for neuropathic pain take time. “People who have reasonable expectations buy in and give us the time we need to try different strategies to find something that works,” she said. In terms of what’s new, Dr. Jacobs said there has been some research on the prevalence of neuropathic pain after cataract surgery, as well as reports on diagnosing neuropathic pain, differentiating central from peripheral processes, and treatment of neuropathic pain. Companies are looking into the treatment of ocular pain, Dr. Galor said, but there is nothing specifically approved for the treatment of neuropathic ocular pain yet. Her ideal treatment would be a topical therapy that maintains corneal sensation and the biologic function of nerves but eliminates pain. Oxervate (cenegerminbkbj, Dompe) is approved for neurotrophic keratitis, a condition distinct from neuropathic pain, in which a patient presents with decreased sensation and epitheliopathy but typically no pain. Dr. Galor said that nerve growth factor may help a subset of patients with neuropathic pain. However, it is not known if the same dose used for neurotrophic keratitis would improve pain in patients with a neuropathic contributor. While ophthalmologists often use products off label with success, the price tag of Oxervate means physicians can’t “play around with the medication” compared to less expensive therapies, Dr. Galor said. In addition to targeted therapies, Dr. Galor sees a need for better diagnostics. “We don’t have a way to test peripheral nerve function or image central nerves. It would be helpful to have such diagnostic tests and pair different therapies to specific diagnostic findings,” Dr. Galor said. EWAP References 1. Venkateswaran N, et al. Periorbital botulinum toxin A improves photophobia and sensations of dryness in patients without migraine: Case series of four patients. Am J Ophthalmol Case Rep. 2020;19:100809. 2. Diel RJ, et al. Photophobia and sensations of dryness in patients with migraine occur independent of baseline tear volume and improve following botulinum toxin A injections. Br J Ophthalmol. 2019;103:1024–1029. 3. Small LR, et al. Oral gabapentinoids and nerve blocks for the treatment of chronic ocular pain. Eye Contact Lens. 2020;46:174–181. Editors’ note: Dr. Galor is a staff physician at Miami Veterans Affairs Medical Center and Associate Professor of Ophthalmology, Bascom Palmer Eye Institute, Miami, Florida, and has interests with Allergan, Dompe, Novaliq, Novartis, Oculis, Oyster Point Pharma, and Shire. Dr. Jacobs is Associate Professor of Ophthalmology, Harvard Medical School, Boston, Massachusetts, and declared no relevant financial interests.
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