Abstract
Purpose :
To evaluate associations between ocular signs and symptoms of dry eye (DE) and somatosensory function in the V1 distribution of the trigeminal nerve.
Methods :
Cross-sectional study of individuals seen in the Miami Veterans Affairs eye clinic with a spectrum of dry eye symptoms and signs (none to severe). The evaluation consisted of questionnaires regarding DE symptoms (dry eye questionnaire 5, DEQ5; ocular surface disease index, OSDI) and ocular pain (numerical rating scale, NRS; short-form McGill Pain Questionnaire, sf-MPQ), a comprehensive ocular surface examination, and quantitative sensory testing (QST) performed on the forehead. QST metrics included threshold measurements of thermal and vibratory sensations, temporal summation of pain, painful aftersensations, and conditioned pain modulation. The main outcome measures were correlations between QST metrics and signs and symptoms of DE.
Results :
100 subjects participated in the study (mean age of 60 ± 10 years, 88% men). Greater severity of DE symptoms and ocular pain were associated with enhanced aftersensations to noxious cold stimulation (a potential indicator of central sensitization of ascending nociceptive information), and more robust descending inhibition of pain (suggestive of an intact descending inhibitory pathway). Conversely, more unhealthy tear film abnormalities were associated with findings of reduced or absent aftersensations to noxious hot stimulation (corneal staining, Schirmer scores).
Conclusions :
These findings suggest dichotomous DE populations with regards to trigeminal somatosensory function, as subjects with more severe DE symptoms and ocular pain had maladaptive responses during and after prolonged noxious stimulation (i.e., central sensitization), while those with abnormal ocular signs exhibited more normative responses to prolonged noxious stimulation on the forehead.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.