Simulation Of Diopter Changes In
Radio Frequency Conductive Keratoplasty
In The Cornea
Author(s)
J. Pearce, D. Panescu & S. Thomsen
Abstract
Correction of hyperopia (far-sightedness) is accomplished by decreasing the
radius of curvature of the cornea. Radio frequency (RF) current at 350 kHz is
presently being used to the required correction. The procedure is termed
Conductive Keratoplasty and temperature increases induced by the RF current
shrink corneal collagen. Finite difference method (FDM) numerical models of
the electric and current density fields, thermal fields, and resulting damage and
collagen shrinkage fields have been used to study the effects of electrode voltage
and power on transient tissue impedance and diopter change obtained from this
process. Water is by far the most thermodynamically active tissue constituent,
and must be taken into account in order to obtain realistic results. Thermal
damage processes are highly non linear, typically following Arrhenius kinetic
rate-limited process formulations, or their equivalent. The FDM model
calculations predict water loss and thermal damage in the form of loss of
birefringence in corneal collagen, which can be directly compared to histologic
section using Transmission Polarizing Microscopy. Numerical model results
compare well with experimental measurements and have been used to study the
relative importance of the governing physical phenomena and the feasibility of
constant power RF activation.
Keywords: surgical simulation, cornea, hyperopia correction, radio frequency
surgery, needle electrode, numerical models, thermal damage prediction.
Keywords
surgical simulation, cornea, hyperopia correction, radio frequency
surgery, needle electrode, numerical models, thermal damage prediction.
Related Book
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