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Dry eye symptoms correlated to non-ocular conditions
Neuropathic pain rather than tear film parameters may correlate to dry eye signs and symptoms.
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Dry eye symptoms may be more closely correlated to non-ocular conditions than tear film status, according to a study.
Because dry eye is caused by different pathophysiological mechanisms, there can be poor correlation between signs and symptoms. Most often, patients are treated with anti-inflammatories, dietary supplements or environmental modifications to improve the tear film, but ocular symptoms have been reported to continue and additional treatments are needed.
Anat Galor, MD, and colleagues have explored the approach that, in some cases, dry eye should be treated similar to neuropathic pain.
“I think this transforms the idea that dry eye is a problem localized to the ocular surface and instead draws the parallel that dry eye can be looked at as a chronic pain condition in some patients,” she told Ocular Surgery News. “The main clinical punch is that we need to rethink dry eye and not just focus on tear production and tear evaporation but also look at other aspects of the disease because just focusing on the ocular surface isn’t enough.”
Neuropathic pain vs. tear parameters
The cross-sectional study, reported in the British Journal of Ophthalmology, evaluated 136 patients at the Miami Veterans Affairs eye clinic to assess dry eye symptoms, non-ocular conditions and tear film parameters. Non-ocular conditions consisted of self-reported non-ocular pain, depression and PTSD, while tear film parameters consisted of osmolarity, tear breakup time, corneal staining, Schirmer’s test, eyelid vascularity and meibum quality.
Correlations among patient responses to the scores of the five-item Dry Eye Questionnaire and the Ocular Surface Disease Index were significant for non-ocular parameters, while correlations with tear film measures were not.
In forward stepwise multivariable linear regression models, non-ocular pain and PTSD were significantly associated with the Dry Eye Questionnaire and OSDI, accounting for 36% and 40%, respectively, of the variability in scores.
“The problem is that a lot of patients continue to have dry eye symptoms on current therapies such as artificial tears and anti-inflammatories,” Galor said, suggesting that not all patients have the same underlying pathophysiology for their dry eye symptoms. “So in patients where those treatments don’t work, we think it’s very important to think about other components such as pain outside the eye and the mental health of the patient.”
Ocular pain therapy approaches
Galor and colleagues attributed the correlation between non-ocular conditions and dry eye symptoms to multiple explanations: Patients with non-ocular conditions may have central sensitization; patients with underlying psychiatric conditions may be misinterpreting ocular surface sensations; or patients with non-ocular pain and psychiatric conditions may be taking medications that affect their tear film status.
“We think that the important step in dry eye is not to call everything dry eye, but to subcategorize dry eye based on pathophysiology and to think about inflammatory-type Sjögren’s dry eye differently than we think about neuropathy ocular pain dry eye,” she said.
Next, Galor would like to explore therapies that enhance nerve function, specifically with proteins in the blood such as nerve growth factor, as well as other types of nerve medications such as systemic Lyrica (pregabalin, Pfizer). Additionally, she plans on researching various tests to look for abnormal nerves and how to treat them.
“I think it’s a very exciting time for dry eye,” Galor said. “It’s a common disease, it has associated morbidity, it has an incredible cost to society, and I think that subdividing and trying to understand pathophysiology of different dry eye are going to help dry eye symptoms in the future.” – by Kristie L. Kahl
- Reference:
- Galor A, et al. Br J Ophthalmol. 2015;doi:10.1136/bjophthalmol-2014-306481.
- For more information:
- Anat Galor, MD, can be reached at the Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St., Miami, FL 33136; email: agalor@med.miami.edu.
Disclosure: Galor reports no relevant financial disclosures.