The presence of a contact lens induces a very small increase in the anterior corneal surface temperature

The anterior corneal surface temperature beneath a contact lens covering the cornea was determined from measurements of the average heat flow from the cornea to the atmosphere (efflux) in a group of 13 healthy young subjects. The average heat efflux was 1.1 X 10(-2) cal X cm-1 X sec-1. The mean corneal surface temperature of the same group was 34.5 degrees C for the open eye and 36.2 degrees C for the closed eye conditions. The anterior corneal surface temperature beneath a 0.07 mm thick hydrogel contact lens (40% water content) was found to be 34.6 degrees C (rise of 0.1 degree C) and 34.9 degrees C (rise of 0.4 degree C) beneath a 0.3 mm thick hydrogel contact lens (40% water content), using the measurement of corneal heat efflux and taking the contact lens to have a slight insulating effect. Contact lenses of higher water content caused a smaller rise in anterior corneal surface temperature than lenses of lower water content.