Calculation of corneal temperature and shrikage during laser thermokeratoplasty  (LTK)

Fabrice Manns; David Borja; Jean-Marie A. Parel

doi:10.1117/12.470581

13 June 2002 Calculation of corneal temperature and shrikage during laser thermokeratoplasty (LTK)

Fabrice Manns, David Borja, Jean-Marie A. Parel

Proceedings Volume 4611, Ophthalmic Technologies XII; (2002) https://doi.org/10.1117/12.470581
Event: International Symposium on Biomedical Optics, 2002, San Jose, CA, United States

Abstract

Purpose. The purpose of this study was to develop a model to predict the corneal temperature and shrinkage during laser thermokeratoplasty and other clinical procedures relying on laser-induced thermal shrinkage of collagenous tissue. Methods. The corneal temperature was calculated by solving the bio-heat equation during laser irradiation using a semi-analytical technique. To calculate shrinkage, we assumed that corneal thermal shrinkage is a thermal denaturation process that follows an Arrhenius equation, and that shrinkage resulting from denaturation is proportional to the amount of thermal damage. We calculated shrinkage for pulsed Ho:YAG laser thermokeratoplasty using the clinical treatment algorithm. Results. The thermal model predicts that the corneal temperature reaches values that may be high enough to induce surface vaporization of the epithelium and thermal damage of the endothelium. Shrinkage calculations show that significant shrinkage is produced only after the third laser pulse. Shrinkage is produced mainly during laser pulses and stops shortly after the start of the cooling phase between laser pulses. Conclusions. These calculations demonstrate that thermal shrinkage can be predicted by combining an optical-thermal model and a thermal denaturation model. Accurate quantitative prediction of the shrinkage effect requires a better knowledge of the dynamics of shrinkage and of the optical thermal response of the cornea.

Citation Download Citation

Fabrice Manns, David Borja, and Jean-Marie A. Parel "Calculation of corneal temperature and shrikage during laser thermokeratoplasty (LTK)", Proc. SPIE 4611, Ophthalmic Technologies XII, (13 June 2002); https://doi.org/10.1117/12.470581

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