title: Corneal Mechanical Thresholds Negatively Associate With Dry Eye and Ocular Pain Symptoms.
abstract: OBJECTIVE
  To examine associations between corneal mechanical thresholds and metrics of dry eye.
  
  
  METHODS
  This was a cross-sectional study of individuals seen in the Miami Veterans Affairs eye clinic. The evaluation consisted of questionnaires regarding dry eye symptoms and ocular pain, corneal mechanical detection and pain thresholds, and a comprehensive ocular surface examination. The main outcome measures were correlations between corneal thresholds and signs and symptoms of dry eye and ocular pain.
  
  
  RESULTS
  A total of 129 subjects participated in the study (mean age 64 ± 10 years). Mechanical detection and pain thresholds on the cornea correlated with age (Spearman's ρ = 0.26, 0.23, respectively; both P < 0.05), implying decreased corneal sensitivity with age. Dry eye symptom severity scores and Neuropathic Pain Symptom Inventory (modified for the eye) scores negatively correlated with corneal detection and pain thresholds (range, r = -0.13 to -0.27, P < 0.05 for values between -0.18 and -0.27), suggesting increased corneal sensitivity in those with more severe ocular complaints. Ocular signs, on the other hand, correlated poorly and nonsignificantly with mechanical detection and pain thresholds on the cornea. A multivariable linear regression model found that both posttraumatic stress disorder (PTSD) score (β = 0.21, SE = 0.03) and corneal pain threshold (β = -0.03, SE = 0.01) were significantly associated with self-reported evoked eye pain (pain to wind, light, temperature) and explained approximately 32% of measurement variability (R = 0.57).
  
  
  CONCLUSIONS
  Mechanical detection and pain thresholds measured on the cornea are correlated with dry eye symptoms and ocular pain. This suggests hypersensitivity within the corneal somatosensory pathways in patients with greater dry eye and ocular pain complaints.
authors.affiliation: Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami, Florida, United States.
authors.forename: Oriel
authors.initials: O
authors.lastname: Spierer
authors.affiliation: Miami Veterans Administration Medical Center, Miami, Florida, United States 3Department of Physical Medicine and Rehabilitation, University of Miami Miller School of Medicine, Miami, Florida, United States.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Felix
authors.affiliation: Miami Veterans Administration Medical Center, Miami, Florida, United States.
authors.forename: Allison L
authors.initials: AL
authors.lastname: McClellan
authors.affiliation: Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami, Florida, United States 4Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami.
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Parel
authors.forename: Alex
authors.initials: A
authors.lastname: Gonzalez
authors.affiliation: Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami, Florida, United States.
authors.forename: William J
authors.initials: WJ
authors.lastname: Feuer
authors.affiliation: Miami Veterans Administration Medical Center, Miami, Florida, United States 5Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, Florida, United States.
authors.forename: Constantine D
authors.initials: CD
authors.lastname: Sarantopoulos
authors.affiliation: Miami Veterans Administration Medical Center, Miami, Florida, United States 5Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, Miami, Florida, United States 6John P. Hussman Institute.
authors.forename: Roy C
authors.initials: RC
authors.lastname: Levitt
authors.affiliation: Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami, Florida, United States 8Brien Holden Vision Institute, University of New South Wales, Sydney, Australia.
authors.forename: Klaus
authors.initials: K
authors.lastname: Ehrmann
authors.affiliation: Anne Bates Leach Eye Hospital, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miami, Florida, United States 2Miami Veterans Administration Medical Center, Miami, Florida, United States.
authors.forename: Anat
authors.initials: A
authors.lastname: Galor
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D015352:Dry Eye Syndromes / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D058447:Eye Pain / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000502:physiology*; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013666:Tears / Q000378:metabolism