title: Effects of oleoresin capsicum pepper spray on human corneal morphology and sensitivity.
abstract: OBJECTIVE
  To examine the potential harmful effects on corneal structure, innervation, and sensitivity of a spray containing the neurotoxin capsaicin (oleoresin capsicum, OC).
  
  
  METHODS
  Ten police officers who volunteered for the study were exposed to OC. Clinical signs were assessed. Corneal sensitivity was measured using a Cochet-Bonnet or a noncontact esthesiometer that provides separate measurements of mechanical, chemical, and thermal sensitivity. Tear fluid nerve growth factor (NGF) was measured. Corneal cell layers and subbasal nerves were examined by in vivo confocal microscopy. The subjects were examined before application and 30 minutes, 1 day, 1 week, and 1 month after OC exposure.
  
  
  RESULTS
  OC spray produced occasional areas of focal epithelial cell damage that healed within 1 day. Each eye showed conjunctival hyperemia and in two subjects, mild chemosis. All except one eye had unchanged best corrected visual acuity (BCVA). A transient decrease (day 1) of mechanical sensitivity was observed with the Cochet-Bonnet esthesiometer. With the gas esthesiometer, mechanical sensitivity remained below normal values for 7 days. Chemical sensitivity to CO2 was high for as much as 1 day and decreased below normal 1 week later, whereas sensitivity to cold was unaffected. Two subjects had measurable tear NGF that increased after exposure. Basal epithelial cell morphology suggested temporary corneal epithelial swelling, whereas keratocytes, endothelial cells, and subbasal nerves remained unchanged.
  
  
  CONCLUSIONS
  Although OC causes immediate changes in mechanical and chemical sensitivity that may persist for a week, a single exposure to OC appears harmless to corneal tissues. The changes are possibly associated with damage of corneal nerve terminals of mainly unmyelinated polymodal nociceptor fibers.
authors.affiliation: Department of Ophthalmology, University of Helsinki, Finland. minna.vesaluoma@hus.fi
authors.forename: M
authors.initials: M
authors.lastname: Vesaluoma
authors.forename: L
authors.initials: L
authors.lastname: Müller
authors.forename: J
authors.initials: J
authors.lastname: Gallar
authors.forename: A
authors.initials: A
authors.lastname: Lambiase
authors.forename: J
authors.initials: J
authors.lastname: Moilanen
authors.forename: T
authors.initials: T
authors.lastname: Hack
authors.forename: C
authors.initials: C
authors.lastname: Belmonte
authors.forename: T
authors.initials: T
authors.lastname: Tervo
mesh_terms: D000328:Adult; D002211:Capsaicin / Q000494:pharmacology*; D003315:Cornea / Q000187:drug effects* / Q000294:innervation / Q000473:pathology*; D019573:Epithelium, Corneal / Q000187:drug effects / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D020932:Nerve Growth Factor / Q000378:metabolism; D009882:Ophthalmic Nerve / Q000187:drug effects* / Q000473:pathology; D010936:Plant Extracts / Q000494:pharmacology*; D012677:Sensation / Q000187:drug effects*; D013666:Tears / Q000378:metabolism; D014792:Visual Acuity / Q000187:drug effects
chemical_list: D010936:Plant Extracts; C018620:oleoresins; D020932:Nerve Growth Factor; D002211:Capsaicin