Correlation between corneal and ambient temperature with particular focus on polar conditions.

Purpose: To examine the relationship between human corneal and environmental temperature.

Methods: An infrared camera was used to measure the corneal surface temperature in a group of healthy volunteers as well as in an experimental setting with donor corneas and an artificial anterior chamber, employing circulating saline at +37°C. Liquid nitrogen was used to obtain a very low temperature in the experimental setting. High ambient temperature measurements were performed in a sauna.

Results: In healthy volunteers, the cornea required at least 20-30 min to adapt to change in ambient temperature. The relationship between corneal and external temperature was relatively linear. At the two extremes, +83°C and -40°C, the corneal temperature was +42°C and +25.1°C, respectively. In the experimental setting, corneal temperature was +24.3°C at air temperature -40°C.

Conclusion: A rather stable aqueous humour temperature of +37°C and high thermal conductivity of the corneal tissue prevent corneal frostbite even at extremely low ambient temperatures.