Transient simulations of heat transfer in human eye undergoing laser surgery

Narasimhan, Arunn; Jha, Kaushal Kumar; Gopal, Lingam

doi:10.1016/j.ijheatmasstransfer.2009.09.007

Cited by 51 publications

(24 citation statements)

References 28 publications

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“…In this model, we derived them for each tissue layer from reported water content, which made them somewhat different from those in previously reported models. 22,33,34 A careful measurement of these properties is likely to improve temperature calculations slightly, but the greatest source of uncertainty is the absorption coefficients. These are not as easily defined and vary by position in the eye, from subject to subject and from species to species.…”

Section: Damage Threshold Temperaturesmentioning

confidence: 99%

Retinal safety of near-infrared lasers in cataract surgery

et al. 2012

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Abstract. Femtosecond lasers have added unprecedented precision and reproducibility to cataract surgery. However, retinal safety limits for the near-infrared lasers employed in surgery are not well quantified. We determined retinal injury thresholds for scanning patterns while considering the effects of reduced blood perfusion from rising intraocular pressure and retinal protection from light scattering on bubbles and tissue fragments produced by laser cutting. We measured retinal damage thresholds of a stationary, 1030-nm, continuous-wave laser with 2.6-mm retinal spot size for 10-and 100-s exposures in rabbits to be 1.35 W (1.26 to 1.42) and 0.78 W (0.73 to 0.83), respectively, and 1.08 W (0.96 to 1.11) and 0.36 W (0.33 to 0.41) when retinal perfusion is blocked. These thresholds were input into a computational model of ocular heating to calculate damage threshold temperatures. By requiring the tissue temperature to remain below the damage threshold temperatures determined in stationary beam experiments, one can calculate conservative damage thresholds for cataract surgery patterns. Light scattering on microbubbles and tissue fragments decreased the transmitted power by 88% within a 12 deg angle, adding a significant margin for retinal safety. These results can be used for assessment of the maximum permissible exposure during laser cataract surgery under various assumptions of blood perfusion, treatment duration, and scanning patterns.

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Section: Damage Threshold Temperaturesmentioning

confidence: 99%

Retinal safety of near-infrared lasers in cataract surgery

et al. 2012

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“…In this formulation (6)(7)(8), the nonlinear dynamics between the velocity u and the temperature θ is calculated simultaneously, which requires an efficient iterative method. The most common practice would solve (6)(7), in the first stage, for u n+1 using either a Newton or Picard type iteration, and then (8), in the second stage, for θ n+1 , which becomes a linear system.…”

Section: Temporal Integrationmentioning

confidence: 99%

“…The most common practice would solve (6)(7), in the first stage, for u n+1 using either a Newton or Picard type iteration, and then (8), in the second stage, for θ n+1 , which becomes a linear system. The present solution method is now outlined.…”

Section: Temporal Integrationmentioning

confidence: 99%

“…Transient simulations of heat transfer problems are often used to advance scientific knowledge in a wide variety of applications such as the design of thermal systems [1; 2; 3], material processing [4; 5; 6], biomedical studies [7], fire protection [8], porous media [9], and weather forecasting [10] -e.g. see [11] for a comprehensive survey of recently published works.…”

Section: Introductionmentioning

confidence: 99%

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A Multiresolution Model for the Simulation of Transient Heat and Mass Transfer

Alam

Kevlahan

Vasilyev

et al. 2012

Numerical Heat Transfer, Part B: Fundamentals

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The development of an efficient computational methodology for transient heat and mass transfer applications is challenging. When a solution is localized on the fraction of a computational domain, an appropriate adaptive mesh method could minimize computational work. In this paper, we propose a novel adaptive-mesh multi-resolution algorithm for the transient momentum and energy equations. The nonlinear dynamics between the velocity and temperature fields is modeled by solving the coupled system of equations simultaneously, where the rate of convergence has been optimized so that computational cost remains proportional to the number of grid points. Numerical experiments have exhibited good agreements with benchmark simulation data.

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“…On the other hand, Ng et al [13], presented a full 3D model, but analysed only the steady state. Narasimhan et al [14] used a 2D model for transient simulations of the human eye undergoing laser surgery.…”

Section: Introductionmentioning

confidence: 99%

Fetd Computation of the Temperature Distribution Induced Into a Human Eye by a Pulsed Laser

Cvetković¹,

Poljak²,

Peratta³

2011

PIER

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Abstract-In this paper we present the three-dimensional finite element time domain model of the human eye exposed to pulsed holmium: YAG laser radiation used in thermokeratoplasty procedure. The model is based on the Pennes' bioheat transfer equation and takes into account the focusing action of the lens. The absorption of laser energy inside the eye tissues is modeled using the Lambert-Beer's law. Model takes into account the pulse temporal profile. The maximum temperature values obtained from steady state and transient analysis are compared against those reported from other papers. Finally, sensitivity analysis of several parameters on the calculated temperature field is carried out.

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Transient simulations of heat transfer in human eye undergoing laser surgery

Cited by 51 publications

References 28 publications

Retinal safety of near-infrared lasers in cataract surgery

Retinal safety of near-infrared lasers in cataract surgery

A Multiresolution Model for the Simulation of Transient Heat and Mass Transfer

Fetd Computation of the Temperature Distribution Induced Into a Human Eye by a Pulsed Laser

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