Somatosensory Function in Patients With Idiopathic Dry Eye Symptoms
JAMA Ophthalmology, November 2016
Symptoms of dry eye (DE) are common among patients who have chronic overlapping pain conditions (COPCs) and are associated with central sensitization. Patients with DE often characterize their ocular pain as burning and report increased sensitivity to wind and light. Galor et al. conducted a prospective cross-sectional study of individuals with a variety of DE symptoms to investigate whether somatosensory dysfunction plays a role in their experience of pain. The researchers found that the severity of neuropathic-like DE pain symptoms correlates with quantitative measures of pain sensitivity at a site remote from the eye (the forearm).
The quantitative sensory test (QST) was used to measure vibratory and thermal thresholds and cold and hot pain temporal summation (TS) in 118 patients treated at the Miami Veterans Affairs Hospital. In addition to receiving QST on the forearm and an ocular surface exam, participants completed the 5-Item Dry Eye Questionnaire, Ocular Surface Disease Index, and Neuropathic Pain Symptom Inventory modified for the eye (NPSI-E). Psychological status was evaluated using the 9-item Patient Health Questionnaire, the PTSD Checklist–Military Version, and the Symptom Checklist–90 for anxiety.
Linear regression analyses showed significant associations between overall DE symptom severity and PTSD scores as well as tear breakup time. Anxiety and hot pain TS at the forearm accounted for 17% of the variability in ocular burning. PTSD score, tear breakup time, and hot pain TS at the forearm explained 25% of the variability in sensitivity to wind and 30% of the variability in total NPSI-E scores. Measures of hot pain TS and aftersensations (15 seconds after cessation of stimulus) on the forearm showed the strongest positive correlation with reported DE symptoms, including neuropathic-like qualities of eye pain and pain sensitivity at the cornea.
In conclusion, these results support the hypothesis that DE symptoms may represent peripheral manifestation of a COPC and may involve somatosensory dysfunction beyond the trigeminal system. (See also invited commentary by Rosenblatt MI.)
The original article can be found here.