Er:YAG laser drilling of cataractous lens: predicting the ablation rate with a simple model

Jeffrey W. Berger M.D.; Seon-Ho Kim; Kevin J. LaMarche; Donald J. D'Amico; Jonathan H. Talamo

doi:10.1117/12.209840

22 May 1995 Er:YAG laser drilling of cataractous lens: predicting the ablation rate with a simple model

Jeffrey W. Berger M.D., Seon-Ho Kim, Kevin J. LaMarche, Donald J. D'Amico, Jonathan H. Talamo

Proceedings Volume 2393, Ophthalmic Technologies V; (1995) https://doi.org/10.1117/12.209840
Event: Photonics West '95, 1995, San Jose, CA, United States

Abstract

We present measurements of the Er:YAG laser drilling rate in human cataractous lens and describe a simple model for mid-infrared laser thermoablation. Lens slabs were immersed in saline and subjected to the output of a free-running Er:YAG laser (2.94 micrometers ). The laser output was directed through a fiberoptic to a 400 micrometers quartz tip. With a radiant exposure of 10 J/cm², and a repetition rate of 10 Hz, we measure an ablation rate of approximately 7 micrometers per pulse and an ablation threshold of 0.6 J/cm². The thermoablation rate varies linearly with radiant exposure. Our model divides the laser pulse into a series of sequential, identical micropulses, (2) solves for the ablation depth for each micropulse, (3) sums the contributions from all micropulses, and (4) specifies that the ablation depth be maximized as a function of the number of micropulses. Predictions of ablation depth and the threshold for tissue ablation are generated. The model yields a linear dependence of penetration depth on radiant exposure and a much larger single pulse penetration depth when compared with the more superficial ablation and logarithmic dependence predicted by Beer's law. Improved correlation of our model with measurements in lens tissue and available experimental data is demonstrated.

Citation Download Citation

Jeffrey W. Berger M.D., Seon-Ho Kim, Kevin J. LaMarche, Donald J. D'Amico, and Jonathan H. Talamo "Er:YAG laser drilling of cataractous lens: predicting the ablation rate with a simple model", Proc. SPIE 2393, Ophthalmic Technologies V, (22 May 1995); https://doi.org/10.1117/12.209840

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