A Parametric Investigation of Corneal Laser Surgery Based on the Multilayer Dynamic Photothermal Model

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Juqi Zhang ◽  
Yatao Ren ◽  
Yanmei Yin ◽  
Hong Qi
Keyword(s):  
Laser Irradiation ◽  
Laser Surgery ◽  
Thermal Damage ◽  
Temperature Response ◽  
Bioheat Transfer ◽  
Corneal Tissue ◽  
Parametric Investigation ◽  
Central Surface ◽  
State Process ◽  
Proposed Model

Abstract Corneal laser surgery is a widely used method for the treatment of ocular myopia, hyperopia, and astigmatism. Although it is a well-established technique, the photothermal properties of the cornea are often overlooked, causing unexpected changes in temperature during laser irradiation. Therefore, there is a need for further investigation of the temperature response of the cornea under laser irradiation. In the present work, a photothermal corneal numerical model is presented, assuming the stratification of the cornea with laser ablation in an uncoagulated layer, a coagulated layer, a dehydrating layer, a dried layer, and a carbonized layer. The modified Pennes' bioheat transfer equation and Lambert-Beer's law are applied to simulate heat transfer in the corneal tissue during laser irradiation. And the corneal dynamic photothermal parameters are considered in the proposed model. The central surface temperature, the boundary and thickness of each layer, and the thermal damage during laser irradiation are investigated. From the model, it was found that in the steady-state process, the thickness of the coagulated layer was 2.6, 14.4, and 52.4 times larger than that of the dehydrating layer, the dried layer, and the carbonized layer, respectively. The thickness of the corneal thermal damage gradually increased, and reached a peak of 0.196 mm at about 18.2 ms. Subsequently, it sharply decreased by 0.01 mm before stabilizing. On this basis, the influence of laser intensity is investigated. The parametric investigation and analysis presented provide a theoretical basis for corneal laser surgery, which can be used to improve our understanding of laser-tissue surgery.

Experiment and simulation of biotissue surface thermal damage during laser surgery

2015 ◽  
Vol 231 (3) ◽  
pp. 581-589 ◽  
Author(s):  
YL Su ◽  
KT Chen ◽  
CJ Chang ◽  
K Ting
Keyword(s):  
Surface Temperature ◽  
Laser Treatment ◽  
Laser Surgery ◽  
Thermal Damage ◽  
Laser Energy ◽  
Irradiation Time ◽  
Damage Zone ◽  
Bioheat Transfer ◽  
Laser Source ◽  
Porcine Liver

In medical cosmetology, laser energy must be properly controlled to avoid unnecessary thermal damage of normal tissue due to excessive irradiation. When a laser source is applied to a specific target that is very close to the surface tissue, residual heat can damage the surface tissue even after the laser treatment is halted. This study aims to determine the proper conditions for the laser treatment and the prediction of the thermal damage of surface tissue after the laser is applied. An 810 nm diode laser was used to irradiate porcine liver and the surface temperature was measured using infrared thermography for different laser application processes. The Pennes bioheat transfer equation was solved using the ANSYS software package to simulate the surface temperature and thermal damage zone in laser surgery. The double ellipsoid function represented the laser source term in the heat transfer simulation. The results of the simulation were compared with the experimental data. Finally, a transient analysis of the estimations of thermal damage after laser surgery was conducted for different conditions of power, laser irradiation time, and laser depth under the surface of the porcine liver.

Modeling thermal damage in skin from 2000-nm laser irradiation

2006 ◽  
Vol 11 (6) ◽  
pp. 064028 ◽  
Author(s):  
Bo Chen ◽  
Sharon L. Thomsen ◽  
Robert J. Thomas ◽  
Ashley J. Welch
Keyword(s):  
Laser Irradiation ◽  
Thermal Damage

scholarly journals Threshold of permanent cornea thermal damage due to incidental continuous wave CO2 laser irradiation

2010 ◽  
Vol 14 (2) ◽  
pp. 459-467 ◽  
Author(s):  
Mayada Tahir
Keyword(s):  
Laser Irradiation ◽  
Co2 Laser ◽  
Thermal Damage ◽  
Continuous Wave ◽  
Anterior Part ◽  
Outer Part ◽  
Human Cornea ◽  
Thermal Dose ◽  
Element Analysis ◽  
Reflex Blink

Cornea thermal damage due to incidental continuous wave CO2 laser irradiation is studied numerically based on bio-heat equation. The interaction of laser with tissue leads to a rapid temperature increased in target and the nearby tissue. As the temperature of the eye surface reaches 44?C, a sensation of pain will cause aversion response of the reflex blink and/or shifting away from the source of pain. The aim of the work is to predict numerically the threshold limit of incidental laser power that causes damage to the anterior part of the cornea, which can be healed within 2-5 days as long as damage is not exceeding the outer part of the eye (epithelium). A finite element analysis is used to predict temperature distribution through the cornea where the necroses region can be obtained using thermal dose equation. The thermal dose that required for damaging the cornea is predicted from previously published experimental data on rhesus monkeys and used later as a limit for shrinkage to human cornea. The result of this work is compared by international standard of safety and a good nearby result is obtained which verified the result of this work.

scholarly journals Thermal Analysis of Cornea Heated with Terahertz Radiation

2019 ◽  
Vol 9 (5) ◽  
pp. 917
Author(s):  
Wenquan Liu ◽  
Yuanfu Lu ◽  
Rongbin She ◽  
Guanglu Wei ◽  
Guohua Jiao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Terahertz Radiation ◽  
Thermal Effects ◽  
Thermal Damage ◽  
Treatment Approach ◽  
Thz Radiation ◽  
Beam Radius ◽  
Corneal Tissue ◽  
Temperature Distributions

We numerically investigate the thermal effects in a cornea illuminated by terahertz radiation. By modifying the bioheat and Arrhenius equations, we studied the heat-transfer and temperature distributions in the corneal tissue, and evaluated the potential thermal damage. The influence of the beam radius and power density are discussed. We also estimated the effective cornea-collagen shrinkage region, and evaluated the degree of thermal damage in the cornea. We expect this work to open up a novel effective and safe thermal-treatment approach based on THz radiation for cornea reshaping in the field of ophthalmology.

scholarly journals Characterization of Thermal Damage Due to Two-Temperature High-Order Thermal Lagging in a Three-Dimensional Biological Tissue Subjected to a Rectangular Laser Pulse

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 922
Author(s):  
Hamdy M. Youssef ◽  
Najat. A. Alghamdi
Keyword(s):  
Fourier Transform ◽  
Biological Tissue ◽  
Thermal Damage ◽  
Three Dimensional ◽  
Bioheat Transfer ◽  
Conduction Model ◽  
Conductive Temperature ◽  
Arrhenius Integral ◽  
The Fourier Transform ◽  
Two Temperature

The use of lasers and thermal transfers on the skin is fundamental in medical and clinical treatments. In this paper, we constructed and applied bioheat transfer equations in the context of a two-temperature heat conduction model in order to discuss the three-dimensional variation in the temperature of laser-irradiated biological tissue. The amount of thermal damage in the tissue was calculated using the Arrhenius integral. Mathematical difficulties were encountered in applying the equations. As a result, the Laplace and Fourier transform technique was employed, and solutions for the conductive temperature and dynamical temperature were obtained in the Fourier transform domain.

Temperature Response in Living Skin Tissue Subject to Convective Heat Flux

2018 ◽  
Vol 387 ◽  
pp. 1-9
Author(s):  
Sanatan Das ◽  
Tilak Kumer Pal ◽  
Rabindra Nath Jana ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Transfer ◽  
Biot Number ◽  
Temperature Response ◽  
Bioheat Transfer ◽  
Heat Transfer Analysis ◽  
Skin Tissue ◽  
Tissue Temperature ◽  
Convective Heating ◽  
Transform Method ◽  
Living Tissues

This paper examines the heat transfer in living skin tissue that is subjected to a convective heating. The tissue temperature evolution over time is classically described by the one-dimensional Pennes' bioheat transfer equation which is solved by applying Laplace transform method. The heat transfer analysis on skin tissue (dermis and epidermis) has only been studied defining the Biot number. The result shows that the temperature in skin tissue is less subject to the convected heating skin compared to constant skin temperature. The study also shows that the Biot number has a significant impact on the temperature distribution in the layer of living tissues. This study finds its application in thermal treatment.

Effect of scanned quasi-cw CO2 laser irradiation on tissue thermal damage

1994 ◽  
Author(s):  
Geoffrey Silver ◽  
Norman S. Nishioka ◽  
Jina Chung ◽  
Yacov Domankevitz ◽  
Dominic Bua ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Co2 Laser ◽  
Thermal Damage ◽  
Cw Co2 Laser
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