Mathematical modeling of laser linear thermal effects on the anterior layer of the human eye

Rahbar, Sahar; Shokooh‐Saremi, Mehrdad

doi:10.1016/j.optlastec.2017.09.033

Cited by 15 publications

(2 citation statements)

References 7 publications

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“…By performing finite element (FE) time domain simulations predicting the temperature distribution in the eye, these restrictions can be overcome. Models [5,[13][14][15][16][17][18][19][20][21][22][23][24][25][26] have been developed to simulate various eye treatments, with the ultimate goal of helping medical practitioners minimise the potential for inadvertent damage to intraocular tissue. Of these previous works investigating laser interaction with the retina, they focused on peak temperature achieved in the RPE at the end of the laser pulse as the dominant absorber.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

Heat transfer simulation in laser irradiated retinal tissues

Truong

Lesniewski

Wedding³

2021

Biomed. Phys. Eng. Express

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“…He assumed the cornea as a semi-infinite region and one-dimensional heat transfer in the tissue region. Rahbar and Shokooh-Saremi [12] presented a mathematical analysis of the thermal effects of the excimer laser on the anterior side of the human eye. They considered the linear effect of an absorption coefficient and the actual dimension of the human eye.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of short pulsed laser irradiation in the cornea: a dual phase lag model

Autar¹,

Kumar²

2021

J. Appl. Math. Comput. Mech.

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A simple mathematical model for the temperature evolution in the cornea exposed to short-pulsed Ho: YAG laser under Laser Thermo Keratoplasty (LTK) treatment is developed by incorporating both the heat flux phase-lag and temperature gradient phase-lag in Fourier's heat transfer model. An analytical solution to the mathematical model is obtained using the Laplace transformation technique. The computational results for the temperature profile and the temperature variation with time are presented through the graphs. The effect of some typical parameters: the heat flux phase-lag and the temperature gradient phase-lag on the temperature distribution and temperature variations are illustrated and discussed.

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Solid‐state laser (266 nm) as an alternative to ArF excimer laser (193 nm) for corneal reshaping: Comparative numerical study of the thermal effect

Abdelhalim,

Hassan,

Abdelkawi

et al. 2024

Numer Methods Biomed Eng

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Laser corneal reshaping is a safe and effective technique utilized to treat common vision disorders. An advanced laser delivery system equipped with a pulsed UV laser with specific parameters is used to ablate parts of the cornea surface to correct the existing refractive error. The argon fluoride (ArF) excimer pulsed gas laser at 193 nm is the most employed type in the commercial devices for such treatments. This laser is generated using a mixture of Argon, Fluorine, and a significant amount of Neon gases. However, due to the ongoing Russian‐Ukraine war, the availability of Neon gas is currently very limited, as this region is considered the primary supplier of pure Neon gas. Consequently we suggest replacing the common ArF laser source in the commercial devices with a solid‐state (forth harmonic neodymium‐doped yttrium aluminum garnet laser at 266 nm). This replacement uses the same operation parameters, optics, and scanning algorithm. Parameters from five commercial devices (Zeiss MEL 90, Technolas TENEO 317, Alcon Wave Light EX 500, Schwind Amaris 750 s, OptoSystems MICROSCAN VISUM) were compared with those of the i‐ablation device, a research device that uses a 266 nm laser source. Our goal is to reduce production costs through a simple modification that has a significant impact. Consequently, the present study aims to find an alternative laser source for the current ArF laser without exchanging the complete system's design. This recommendation is based on a numerical simulation study. The thermal effect on a human cornea model was numerically evaluated using finite‐element solutions of Pennes' bioheat equation on the COMSOL platform by applying two laser wavelengths. The results demonstrated that changing the laser source significantly impacts the thermal effect, even with the same laser settings. All studied devices showed a reduction in the thermal effect to below 40°C, compared with nearly 100°C under ordinary conditions.

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Mathematical modeling of laser linear thermal effects on the anterior layer of the human eye

Cited by 15 publications

References 7 publications

Heat transfer simulation in laser irradiated retinal tissues

Heat transfer simulation in laser irradiated retinal tissues

Mathematical modeling of short pulsed laser irradiation in the cornea: a dual phase lag model

Solid‐state laser (266 nm) as an alternative to ArF excimer laser (193 nm) for corneal reshaping: Comparative numerical study of the thermal effect

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