Corneal Mechanical Hypersensitivity is Correlated with Wind Hyperalgesia, Ocular Symptoms, and Systemic Complaints.

Abstract

Purpose: To use the Belmonte aesthesiometer as a quantitative sensory testing instrument to evaluate correlations between evoked sensory responses on the cornea and dry eye symptoms, signs, and systemic parameters.

Methods: Design: Cross-sectional study.<br /> Participants: Individuals seen in the Miami Veterans Affairs eye clinic.<br /> Intervention: An evaluation was performed consisting of standardized questionnaires regarding ocular and non-ocular (systemic) symptoms, corneal mechanical detection and pain thresholds via the modified Belmonte aesthesiometer, and a comprehensive ocular surface examination. Questionnaires inquired about dry eye symptoms (dry eye questionnaire 5, ocular surface disease index), ocular pain (neuropathic pain symptom inventory and short form McGill Pain Questionnaire applied to ocular pain), and non-ocular complaints (numerical rating scale for non-ocular pain, posttraumatic stress disorders (PTSD) Checklist - Military Version (PCL-M), depression (patient health questionnaire 9)). Main outcome measures: Correlations between corneal detection and pain thresholds and dry eye symptoms, signs, systemic complaints.

Results: One hundred and nine subjects participated in the study (mean age 64 ± 11 years). Evoked sensory responses on the cornea all correlated with age (mechanical detection thresholds r=0.24, pain thresholds r=0.23, intensity ratings at the pain threshold r=-0.20, p<0.05 for all), implying decreased corneal sensitivity with age. Dry eye symptoms and ocular pain, on the other hand, correlated negatively with corneal detection and pain thresholds (r=-0.11to -0.25) and positively with higher intensity ratings at the pain thresholds (r=0.12-0.27), implying increased corneal sensitivity in those with ocular complaints. Ocular signs, on the other hand, correlated poorly and non-significantly with these parameters. Non-ocular pain also negatively correlated with corneal detection thresholds. A multivariable linear regression model found that age and self-reported wind hyperalgesia were the variables most closely associated with detection and pain thresholds, after accounting for ocular symptoms, signs, and systemic co-morbidities.

Conclusions: Self-reported wind hyperalgesia, ocular symptoms, and non-ocular pain correlate negatively with corneal mechanical thresholds.