Comparison of laser phacovaporization using the Er-YAG and the Er-YSGG laser.

Objective: To study the interaction of the erbium (Er)-YAG (2.94 microns) and the Er-YSGG (2.79 microns) lasers with the human crystalline lens tissue.

Methods: Fresh human crystalline lens sections were used to measure the photovaporization threshold, rate, and damage zone of the two lasers.

Results: We found the photovaporization threshold for the Er-YAG and the Er-YSGG lasers to be 1.4 J/cm2 and 5.5 J/cm2, respectively. At 10 J/cm2, the photovaporization rate is 67.9 microns per pulse for the Er-YAG laser and 18.4 microns per pulse for the Er-YSGG laser. The increased rate of photovaporization as a function of radiant energy for the Er-YAG laser is almost twice that for the Er-YSGG. Damage zones for the Er-YAG laser ranged from 4 to 9 microns compared with 10 to 22 microns for the Er-YSGG.

Conclusions: It is apparent that both lasers can adequately photovaporize human crystalline lens tissue and should be further studied for this purpose.