title: Selective changes in human corneal sensation associated with herpes simplex virus keratitis.
abstract: OBJECTIVE
  To determine corneal sensitivity to selective mechanical, chemical, and thermal (heat and cold) stimulation in patients with a history of herpes simplex virus (HSV) keratitis.
  
  
  METHODS
  Corneal sensitivity to different modalities of stimulus was determined in both eyes of 16 patients with unilateral HSV keratitis diagnosed 1 to 12 months before the study. On slit lamp examination, 13 HSV-affected eyes showed corneal scarring or opacities, and three had no signs of previous keratitis. Corneal sensitivity was determined with the Belmonte gas esthesiometer. Mechanical, chemical, heat, and cold stimuli were applied on the central cornea. Eyes from 10 healthy subjects served as controls.
  
  
  RESULTS
  In all control and contralateral eyes, selective mechanical, chemical, heat, and cold stimulation evoked sensations of subjective intensity proportional to the magnitude of the applied stimulus. In one HSV patient, the affected cornea was unresponsive to all types of stimuli, four lost only corneal sensitivity to mechanical stimulation, and three lost only sensitivity to heat. Mechanical (P<0.005) and heat (P<0.05) thresholds were raised in HSV eyes, whereas thresholds for CO2 were not modified. Also, HSV subjects identified poorly the intensity of mechanical, chemical, and heat stimuli, whereas sensitivity to cold stimulation was unaffected.
  
  
  CONCLUSIONS
  In eyes that had had HSV keratitis, corneal sensitivity to mechanical forces and heat was significantly impaired, suggesting that axonal damage and/or altered expression of membrane ion channels involved in transduction and membrane excitability affects primarily the mechano- and polymodal nociceptor terminals. Corneal cold-sensitive terminals remain largely unaffected.
authors.affiliation: Instituto de Neurociencias, Universidad Miguel Hernandez-CSIC, San Juan de Alicante, Spain. juana.gallar@umh.es
authors.forename: Juana
authors.initials: J
authors.lastname: Gallar
authors.forename: Timo M T
authors.initials: TM
authors.lastname: Tervo
authors.forename: Waldir
authors.initials: W
authors.lastname: Neira
authors.forename: Juha M
authors.initials: JM
authors.lastname: Holopainen
authors.forename: Maria E
authors.initials: ME
authors.lastname: Lamberg
authors.forename: Fernando
authors.initials: F
authors.lastname: Miñana
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Acosta
authors.forename: Carlos
authors.initials: C
authors.lastname: Belmonte
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002921:Cicatrix / Q000503:physiopathology / Q000821:virology; D003080:Cold Temperature; D003315:Cornea / Q000294:innervation* / Q000502:physiology / Q000821:virology; D005260:Female; D006358:Hot Temperature; D006801:Humans; D016849:Keratitis, Herpetic / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology / Q000821:virology*; D017288:Pain Threshold; D010812:Physical Stimulation; D011984:Sensory Receptor Cells / Q000502:physiology* / Q000821:virology; D013268:Stimulation, Chemical; D055815:Young Adult