Corneal mechanical sensitivity in individuals with chronic pain

Abstract

Purpose : To examine corneal mechanical thresholds in individuals with chronic pain using a Belmonte aesthesiometer.

Methods : We performed a cross-sectional study of South Florida veterans with chronic pain conditions (>3 months duration) seen at an eye clinic. Individuals were split into two groups based on the location of their pain: Group 1 included individuals with chronic pain conditions that involved the trigeminal system (e.g. migraine, burning mouth syndrome, trigeminal neuralgia, and trigeminomandibular disorder) while Group 2 included individuals with chronic pain conditions that did not involve the trigeminal system (e.g. back pain, knee pain). Dry eye symptoms and signs, systemic co-morbidities, and quality of life indices were also assessed via standardized questionnaires. Corneal mechanical thresholds were assessed using a modified Belmonte aesthesiometer. Our main outcome measure was comparison of mean corneal mechanical thresholds between our two groups via the independent t-test. Multivariable linear regression analysis was also performed to evaluate predictors of corneal mechanical threshold (dependent variable) while considering multiple independent variables (e.g. demographics, pain location, dry eye symptoms, signs, co-morbidities, quality of life). All reported p-values are two-tailed and p<0.05 was considered statistically significant.

Results : The mean age of the 577 individuals included in the study was 61±10.5 years; 89% were male, 45% self-identified as white, and 25% as Hispanic. Mean corneal mechanical threshold was lower among individuals with chronic trigeminal pain (n=123) compared to those without (n=454), 75±43 vs 86±43 mL/min, p=0.015. Multivariable analysis on 320 individuals with data for all variables demonstrated quality of life questionnaire scores (standardized β= -0.49, p=0.002), dry eye symptoms (β= -0.30, p=0.039), and presence of chronic trigeminal pain (β= -0.44, p=0.002) remained significant predictors of corneal mechanical detection threshold, with an overall R²=0.34 for the model.

Conclusions : Chronic trigeminal pain, worse quality of life, and dry eye symptoms predicted lower corneal mechanical thresholds (higher sensitivity). This suggests a link between chronic trigeminal pain, quality of life, and corneal sensitivity.

This is a 2021 ARVO Annual Meeting abstract.