Transient simulations of heat transfer in human eye undergoing laser surgery

A validated two-dimensional computational model of the human eye solving the discretized form of the bio-heat transfer equation using finite volume formulation has been developed. Using the model, the transient temperature evolution and associated thermal effects in various regions of the human eye subjected to laser radiation during retinopathy are investigated. It is shown that the transient evolution of the retinal temperature during laser heating could reach values higher than that required for irreversible cell damage. This 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). This excess temperature could cause cell damage to the adjoining retinal region due to heat diffusion. Based on the simulation results, a method is proposed to maintain the retinal pigmented epithelium (RPE) temperature close to the required 60 °C by pulsating the laser source between suitable maximum and minimum heat flux values.