Numerical Simulations of Heat Transport in Human Eye Undergoing Laser Surgery
Kaushal Kumar Jha1 and Arunn Narasimhan2
1Research Scholar, Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering,
Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
kaushal.jha@gmail.com
2Assistant Professor, Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering,
Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
arunn.iitm.ac.in
ABSTRACT
A geometrically faithful, validated, two dimensional computational model of the human eye solving the discretized form of the bioheat transfer equation using finite volume formulation has been developed. Using this model, the transient temperature evolution and associated thermal effects in various regions of the human eye subjected to (Argon) laser radiation during retinopathy is investigated. It is shown that the retinal temperatures during laser heating could reach values higher than that required for irreversible cell damage or photocoagulation (60°C). For a 0.2 W laser power and 500 micron spot diameter, peak temperatures during steady state and transient simulation of 100 ms are 172°C and 100°C respectively. This overheating in transient operation is because the time scale for spatial diffusion of heat towards the choroid, containing blood vessels for cooling, is much larger than that of the actual laser surgical process (100 ms). A method has been proposed to calculate the reduced laser power requirement to keep the peak temperature in the range suitable for photocoagulation, to reduce the extent of the heat affected zone. It has been established analytically and also through numerical simulation that the reduced laser power requirement for a 500 µm spot size, should be equal to 0.072 W.
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