In this study a thermographic system has been used to analyze and compare three phacoemulsification based cataract surgery procedures. During all the surgical procedures, performed in vivo, the temperature of the ocular surface was acquired and the temperature values in the area where the phaco tip was inserted in the eye were measured. Moreover, using a suitable index, the heat transmitted to the eye during the procedure was assessed. The surgical procedure which has the lowest thermal impact on the eye has been detected. Thermography, used in this study as a temperature monitoring instrument, has been applied in vivo without requiring any change in the surgical procedure, has allowed analysis to be effected through a useful and advantageous methodology, totally non-invasive as regards both surgeon and patient.