Dry Eye Linked to Increased Risk of Headache, Migraine

A large study of individuals in the Veterans Affairs (VA) system has found that people with dry eye are at increased risk for a number of pain conditions, including headache and migraine.[1]

Dry eye affects about 15% of the US population.[2] Dry eye may share common mechanisms with COPCs, such as inflammation, nerve sensitization, genetic susceptibility, and psychosocial vulnerabilities. Whether dry eye can be considered a COPC has yet to be established.

To assess the association between dry eye and comorbid pain conditions, researchers conducted a retrospective medical records review using nationwide data from the VA Healthcare System database. The study included veterans who received a diagnosis of dry eye in VA facilities between January 2010 and December 2014 [link to study]. Over those 5 years, 29.4% (n=959,881) of veterans seen at VA facilities received a diagnosis of dry eye. Researchers further analyzed individuals with dry eye according to whether they had tear film dysfunction (25.2%) or ocular pain (5.7%). Results were adjusted for demographics and pain comorbidities. In general, the frequency of dry eye increased along with increasing number of pain conditions (p<0.0005).

Pain diagnoses most closely related to ocular pain included:
-Headache: Almost 2 times increased risk (OR1.96; 95% CI 1.94–1.98)
-Migraine: 1.4 times increased risk (OR 1.41; 95% CI 1.39–1.44)
-Postherpetic neuralgia: 1.4 times increased risk (OR 1.42; 95% CI 1.35–1.49)
-All p < 0.0005

Pain diagnoses most closely related to tear film dysfunction included:
-Postherpetic neuralgia: 1.4 times increased risk (OR 1.41; 95% CI 1.36–1.45)
-Osteoarthritis: 1.3 times increased risk (OR 1.39; 95% CI 1.38–1.40)
-Diabetic neuropathy: 1.3 times increased risk OR 1.25; 95% CI 1.24–1.27)
-All p < 0.0005

The findings support dry eye as a COPC and suggest shared mechanisms, according to the authors. Somatosensory dysfunction may underlie some subtypes of dry eye, especially ocular pain. The authors noted that the study contained about 90% male veterans, who have a higher prevalence of mental health disorders and chronic pain conditions. The results may not generalize to women or a more diverse population.

Take Home Points
-Study in the VA system suggests that frequency of dry eye increases with increasing pain conditions
-Headache, migraine, and postherpetic neuralgia were most closely linked to ocular pain
-Postherpetic neuralgia, osteoarthritis, and diabetic neuropathy were most closely linked to tear film dysfunction
-Results support dry eye as a chronic overlapping pain condition, a group of disorders that includes headache

1. Lee CJ, Levitt RC, Felix ER, et al. Evidence that dry eye is a comorbid pain condition in a US veteran population. Pain Reports. 2017;2(6):e629. doi:10.1097/PR9.0000000000000629.
2. International Dry Eye Workshop. The epidemiology of dry eye disease: report of the Epidemiology Subcommittee of the International Dry Eye WorkShop (2007). Ocul Surf. 2007;5:93-107.