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  • Bio-heat transfer simulatio...
    Narasimhan, Arunn; Jha, Kaushal Kumar

    International journal for numerical methods in biomedical engineering, 05/2012, Letnik: 28, Številka: 5
    Journal Article

    SUMMARY Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two‐dimensional numerical model of the human eye geometry has been developed to investigate transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentation and that of choroidal blood convection—parameterized as a function of choroidal blood perfusion—are investigated in detail. The Pennes bio‐heat transfer equation is invoked as the governing equation, and finite volume formulation is employed in the numerical method. For a 500‐ μm diameter spot size, laser power of 0.2 W, and 100% absorption of laser radiation in the retinal pigmented epithelium (RPE) region, the peak RPE temperature is observed to be 103 °C at 100 ms of the transient simulation of the laser surgical period. Because of the participation of pigmented layer of choroid in laser absorption, peak temperature is reduced to 94 °C after 100 ms of the laser surgery period. The effect of choroidal blood perfusion on retinal cooling is found to be negligible during transient simulation of retinopathy. A truncated three‐dimensional model incorporating multiple laser irradiation of spots is also developed to observe the spatial effect of choroidal blood perfusion and choroidal pigmentation. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, transient temperature evolution using simultaneous and sequential mode of laser surgical process is presented with analysis. Copyright © 2012 John Wiley & Sons, Ltd. Retinal laser surgery is simulated in three dimensions with the use of the bio‐heat transfer model. Sequential and simultaneous modes of irradiation for single‐spot and multiple‐spot array are considered. The effects of retinal and choroidal pigmentation as well as choroidal blood perfusion on the retinal temperature distribution are analyzed. Irrespective of blood perfusion, choroidal pigmentation is found to have significant effect on retinal temperature distribution.