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 mum) and the Er-YSGG (2.79 mum) 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 ErYSGG lasers to be 1.4 J/cm2 and 5.5 J/cm2, respectively. At 10 J/cm2, the photovaporization rate is 67.9 mum per pulse for the Er-YAG laser and 18.4 mum 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 mum compared with 10 to 22 mum 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.