[In vivo measurement of temperature during phacoemulsification]

Based on our experience of in vitro measurements of temperature in the anterior chamber in 1994 we designed a new spatula with an integrated probe that enabled us to measure temperature continuously during phacoemulsification without any surgical effort.

We measured the temperature in the anterior chamber during 50 cases of phacoemulsification. Depending on the indications, we used different energy modes (0-100%) and pulse modes ranging from 3 to 10 pulses per second or continuous ultrasonic output. Different viscoelastic substances were also used.

The average temperature in the anterior chamber was 30 degrees C and adapted to the temperature of the irrigation fluid within seconds as soon as irrigation was started. During phacoemulsification each ultrasonic output causes an increase of temperature. In the case of continuous mode, the maximum rise in temperature was 3.5 degrees C. When the pulse mode was used the temperature increased up to 1.7 degrees C. It is important to note that one single pulse may increase the temperature by 0.8 degree C close to the phacotip. The rise of temperature correlated with the viscosity of the viscoelastic substance used.

The new probe proved to be a practical device to monitor temperature in the anterior chamber during phacoemulsification. Up to now we did not encounter any critical degrees of temperature but it should be pointed out that a functional irrigation unit, the use of pulse mode or permanent ultrasonic output and in particular the type of viscoelastic material used are all important parameters influencing the rise of temperature during phacoemulsification. Further experience and results obtained with the new probe will be reported in the future.