Refractory dry eye linked with neuropathic or systemic pain

NEW YORK - Subjective responses to artificial tears for dry eye differ based on the presence of neuropathic ocular and systemic pain, according to researchers.

"Our results are novel and important because they suggest that a well-established set of patient symptoms may help direct treatment decisions," the researchers wrote online September 16 in the British Journal of Ophthalmology.

"Dry eye is not one thing, and different types of dry eye should be treated differently," Dr. Anat Galor, of the Miami Veterans Administration Medical Center, Miami, Florida, told Reuters Health by phone.

Dr. Galor and colleagues recruited 118 patients from the Miami Veterans Administration eye clinic who were using artificial tears (hypromellose 0.4%, Natural Balance) to treat dry eye-associated ocular pain. None had photorefractive surgery or concomitant ocular comorbidities, such as glaucoma, or post-herpetic pain, and none used contact lenses. All underwent a complete ocular surface examination and tear film assessment.

The mean age was 65; most were male.

Twenty-three patients reported no improvement, 73 reported partial improvement, and 22 reported complete improvement.

There were no significant differences in mean duration of use (no improvement, 32 months; partial improvement, 41 months; and complete improvement, 23 months) or in mean frequency of use (2.7, 2.6 and 2.3 times/day, respectively).

However, the presence of neuropathic ocular pain (i.e., hot-burning ocular pain and sensitivity to wind) did differ significantly between the three groups. Patients with no or partial relief had higher pain and sensitivity scores compared with those who reported complete improvement (p<0.05).

A higher systemic pain score was significantly associated with an incomplete self-reported treatment response to artificial tears (odds ratio 1.35, p=0.003), the authors reported.

Also, compared with those who had complete improvement, patients with no or partial relief had higher depression scores (p=0.047). And patients with no or partial improvement response used anxiolytics or antihistamines more frequently than patients with a complete response (p<0.05).

Among ocular signs, abnormal meibum quality was the only physical finding associated with reduced risk of an incomplete treatment response (OR 0.12, p=0.004).

"This study may heighten provider awareness that nervous system sensitization may be contributing to symptoms in patients who do not respond to artificial tears," Dr. Joanne F. Shen, ophthalmology chair and director of the Dry Eye Clinic at the Mayo Clinic in Arizona, told Reuters Health by email.

She said that referral to a neurologist may help start patients on systemic approaches for central or peripheral nerve sensitization. However, this hypothesis is new, and many neurologists may not understand their role in treating patients with the ocular equivalent of chronic pain syndrome, she added.

Dr. Galor recommends referral to a psychologist or pain specialist.

Both doctors agree that the study has limitations, including its cross-sectional design, its unique sample of male veterans, the use of self-reported data, and no follow-up.

Nonetheless, it provides a useful, quick, and inexpensive way to categorize patients with dry eye and get important information about how they'll respond to therapy, said Dr. Galor.

"Dry eye is really about subtyping and tailoring treatment based on the underlying pathophysiology," she said. "We do patients with neuropathic ocular pain a disservice by calling their condition dry eye and treating them like everyone else."

SOURCE: http://bit.ly/1RCLZlk

Br J Ophthalmol 2015.

References: Reuters Health
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