title: Thermodynamic measurement after cooling the cornea with intact epithelium and lid manipulation.
abstract: OBJECTIVE
  To characterize the rate of change of ocular surface temperature (OST) under lid manipulation after cooling the intact cornea with balanced salt solution (BSS).
  
  
  METHODS
  In a patient for refractive surgery, prior to the ablation, the temperature of the cornea was continuously recorded with a high speed infrared (350Hz) camera. Two millilitre of chilled BSS with a temperature of 8.6°Celsius (°C) was instilled for about 3s. Using exponential functions, the three contributions have been determined, subjacent corneal layers, environment, and chilled BSS.
  
  
  RESULTS
  The mean temperature of the cornea preoperatively was 34.5°C. After applying the chilled BSS the temperature decreased about 14°C down to an OST of 20°C and the time needed afterwards to get the normal (OST) temperature of about 30°C was 40s. Due to the inserted speculum and missing blink, OST did not reach the original OST of 34.5°C and faded at about 32.5°C. According to our best fitted model, absolute value of each contributing component was 31.4°C (subjacent corneal layers), 26.8°C (environment) and 8.6°C (BSS).
  
  
  CONCLUSIONS
  Applying chilled BSS to the cornea quickly reduces the temperature of the cornea with a thermal relaxation time of 3s and a amplitude decrease of 8.6°C. This together with a relaxation time of 7s for subjacent corneal layers, and 184s for environment after instillation of BSS combined with a well-controlled environment provides a period of 40s of corneal temperature below baseline, which may be of clinical benefit when applying chilled BSS immediately before or immediately after ablation.
authors.affiliation: Augenzentrum Recklinghausen, Recklinghausen, Germany; Consultant to SCHWIND Eye-tech Solutions, Kleinostheim, Germany. Electronic address: diego.de.ortueta@augenzentrum.org.
authors.forename: Diego
authors.initials: D
authors.lastname: de Ortueta
authors.affiliation: Employees SCHWIND Eye-tech Solutions, Kleinostheim, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Magnago
authors.affiliation: Employees SCHWIND Eye-tech Solutions, Kleinostheim, Germany.
authors.forename: Samuel
authors.initials: S
authors.lastname: Arba-Mosquera
mesh_terms: D001831:Body Temperature; D003080:Cold Temperature; D003315:Cornea / Q000502:physiology / Q000601:surgery*; D005126:Eye Burns / Q000517:prevention & control*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D007431:Intraoperative Complications / Q000517:prevention & control*; D054018:Lasers, Excimer / Q000627:therapeutic use; D018903:Photorefractive Keratectomy / Q000379:methods*
keywords: BSS; Balanced salt solution; Cooling; Corneal surface; Enfriamiento; Solución salina equilibrada; Superficie corneal; Temperatura; Temperature