Some dry eye patients may experience severe pain that reduces their quality of life, and while topical treatments can mitigate local immune responses and reduce inflammation, this approach doesn’t always resolve the issue if the underlying pain is neuropathic in nature.
A recent study reported that oral gabapentin may be able to successfully treat DED patients with neuropathic ocular pain—as opposed to pain mainly caused by mechanical and chemical influences—who have systemic comorbidities, including rheumatological, neurological and psychological disorders. Gabapentin is a potent blocker of nerve sensitization used to treat epilepsy and post-herpetic neuralgia; a related formulation (pregabalin) treats peripheral neuropathy.
The research team from Korea found that this treatment may be even more effective in patients who have more severe corneal staining scores and no prior history of ocular surgery or trauma.
The retrospective investigation evaluated 35 patients with DED accompanied by neuropathic ocular pain. Participants underwent evaluations of the tear film, ocular surface and meibomian glands and completed an Ocular Pain Assessment Survey (OPAS). One month after treatment with topical eye drops, the researchers added gabapentin to the treatment regimen according to the results of a pain scale. A reduction of two or more points on the pain scale was considered a positive treatment response. The patients were accordingly divided into three groups: topical treatment response group (n=11), gabapentin response group (n=13) and gabapentin non-response group (n=11).
The researchers noted the incidence of systemic comorbidities was higher in the gabapentin response group. Corneal staining scores were lower in both the gabapentin response and non-response groups. Looking at the OPAS scores post-treatment, the gabapentin response group showed improvements in ocular pain severity, non-ocular pain severity and quality of life. Gabapentin can relieve neuropathic pain and general systemic symptoms, such as mood, sleep and vasomotor factors, which could explain the significant improvement in non-ocular pain severity and quality of life score, the researchers suggested.
Patients who responded to topical treatment had improved scores in ocular pain severity and ocular associated factors. The gabapentin response group also had lower scores in pain aggravated by mechanical and chemical stimuli compared with the topical treatment group.
Individuals with previous ocular history, including surgery and trauma, may not respond to topical treatment and require systemic neuropathic ocular pain treatment, the investigators noted. The sensory neurons of the ocular surface and nociceptors can actually be injured in patients who had ocular surgery and trauma, leading to neuroinflammation associated with peripheral and central sensitization, the researchers explained. Topical anti-inflammatory agents, such as steroids and cyclosporine, may decrease the release of pro-inflammatory neuropeptides and cytokines from injured nerves, affecting nociceptive pain and peripheral sensitization, they said.
Yoon HJ, Kim J, Yoon KC. Treatment response to gabapentin in neuropathic ocular pain associated with dry eye. J Clin Med. 2020;9(11):3765.