A prediction model for ocular damage – Experimental validation

Heussner, Nico; Vagos, Marcia; Spitzer, Martin S.; Stork, Wilhelm

doi:10.1016/j.jtherbio.2015.05.005

Cited by 9 publications

(4 citation statements)

References 27 publications

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“…Such application treated as non-biological included the industrial preparation of baked goods [79], materials science [80][81][82], biomechanical surgery tool maintenance [83], assessment of building materials in agricultural management [84] and canal upkeep [85]. Biomechanical studies where temperatures of artificial replacements were only monitored outside the body, for example, in mechanical stress assessment [86], and studies where biological tissue mimics were employed instead of real biological targets [87,88] were likewise excluded as 'not biological'.…”

Section: Exclusion Criteriamentioning

confidence: 99%

Reporting of thermography parameters in biology: a systematic review of thermal imaging literature

et al. 2018

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Infrared (IR) thermography, where temperature measurements are made with IR cameras, has proven to be a very useful and widely used tool in biological science. Several thermography parameters are critical to the proper operation of thermal cameras and the accuracy of measurements, and these must usually be provided to the camera. Failure to account for these parameters may lead to less accurate measurements. Furthermore, the failure to provide information of parameter choices in reports may compromise appraisal of accuracy and replicate studies. In this review, we investigate how well biologists report thermography parameters. This is done through a systematic review of biological thermography literature that included articles published between years 2007 and 2017. We found that in primary biological thermography papers, which make some kind of quantitative temperature measurement, 48% fail to report values used for emissivity (an object's capacity to emit thermal radiation relative to a black body radiator), which is the minimum level of reporting that should take place. This finding highlights the need for life scientists to take into account and report key parameter information when carrying out thermography, in the future.

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Section: Exclusion Criteriamentioning

confidence: 99%

Reporting of thermography parameters in biology: a systematic review of thermal imaging literature

et al. 2018

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“…(1a). A good outline of bio-heat formulations including blood perfusion following the 'Pennes model' has been presented in recent studies by Heussner et al [39] while a review of the eye blood flow models is offered by Flyckt et al [18], and of main bio-heat models indicating imperfections of the Pennes model, by Tzu-Ching Shih et al [40]. Investigations of the effect of heat convection by blood perfusion was previously explored by Welch et al [41] where choroidal blood perfusion was represented by a constant heat transfer of 65 W m −2 K −1 and by Sramek et al [25] where the blood perfusion rate was taken as 0.3 s −1 .…”

Section: 2mathematical Formulation Of Heat Transfermentioning

confidence: 99%

Heat transfer simulation in laser irradiated retinal tissues

Truong

Lesniewski

Wedding³

2021

Biomed. Phys. Eng. Express

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A realistic model of human retinal tissues to simulate thermal performance of optical laser photocoagulation therapy is presented. The key criteria to validate the treatment effectiveness is to ensure the photocoagulation temperature between 60 and 70°C is reached in the treatment region of interest. The model presented consists of truncated volumes of the retinal pigment epithelium (RPE) and adjacent retinal tissues. Two cases of choroid pigmentation are modelled to signify extreme cases of human eye difference: albino and dark colour choroid pigmentation. Conditions for consistent heating over the irradiated treatment spot is modelled for laser beams with different intensity profiles: ‘top-hat’, Gaussian and ‘donut’ modes. The simulation considers both uniform heating within retinal tissue layers and spatial intensity decay due to absorption along the direction of laser propagation. For a 500 m spot, pulse length 100 ms and incident power to the cornea of 200 mW, realistic spatial variation in heating results in peak temperatures increasing within the RPE and shifting towards the choroid in the case of choroidal pigmentation. Finite element analysis methodology, where heat transfer theory governs the temperature evolution throughout tissues peripheral to the irradiated RPE is used to determine the zone of therapeutic benefit. While a TEM01 donut mode beam produces lower peak temperatures in the RPE for a given incident laser power, it reduces the volume of retinal tissue reaching excessive temperatures and maximises the zone of therapeutic benefit. Described are simulation limitations, boundary conditions, grid size and mesh growth factor required for realistic simulation.

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“…The temperature distribution of the entire fundus tissue layer involves a complicated and inconvenient computation. In the multilayer homogeneous model, the ocular fundus is divided into several layers with uniform thermal, physical, and optical parameters, i.e., each layer is regarded as an isotropic homogeneous medium (Amin et al, 2015;Welch, 2011, Heussner, 2015Cvetkovi et al, 2011). This model offers high computational efficiency and accuracy, but it is only suitable for laser with long pulse duration.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of ophthalmic laser surgeries by a local thermal non-equilibrium two-temperature model

Chen

Zhao

2019

HFF

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Purpose This paper aims to understand the laser–tissue interaction mechanism during ophthalmic laser surgeries through numerical analysis. The influence of laser parameters and the multipulse technique were investigated. Design/methodology/approach The ocular fundus was simplified as a multilayered homogenous medium model. Afterward, the multilayer Monte Carlo method was used to simulate the propagation and energy deposition of laser light, and a local thermal non-equilibrium two-temperature model was established to simulate the temperature variation of chromophores and surrounding tissue with different laser wavelength. Findings Through the model, the selective heating of chromophore (melanin and blood vessels) was clearly illustrated: 1) neglecting the laser energy absorbance by blood in the traditional model will cause significant errors in temperature calculation; 2) the non-thermal equilibrium heat transfer model was needed to obtain an accurate description of the thermal process when the dimensionless pulse width (tp*) is <105. For 532 nm Argon laser, the optimize tp* is around 105 and the appropriate energy density is 5 J/cm2; 3) multipulse technique makes the energy more concentrated within the melanin, thereby reducing the thermal damage in surrounding tissue, with most appropriate pulse number and duty cycle is 10 and 1/10. Originality/value Taking the blood absorption into account, the different temperature variations of melanin/vessels and surrounding tissue caused by the selective photo-thermolysis were simulated successfully. By understanding the mechanism of laser therapy, laser parameters and multipulse technique are suggested to improve the clinical results.

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A prediction model for ocular damage – Experimental validation

Cited by 9 publications

References 27 publications

Reporting of thermography parameters in biology: a systematic review of thermal imaging literature

Reporting of thermography parameters in biology: a systematic review of thermal imaging literature

Heat transfer simulation in laser irradiated retinal tissues

Numerical simulation of ophthalmic laser surgeries by a local thermal non-equilibrium two-temperature model

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