A modeling approach for laser-induced thermal damage to the human eye is presented. It aims to improve the evaluation of laser-based hazards by providing a means of calculating the damage for a specific irradiation scenario.
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Method Article
A modeling approach for laser-induced thermal damage to the human eye is presented. It aims to improve the evaluation of laser-based hazards by providing a means of calculating the damage for a specific irradiation scenario.
With the increasing number of laser applications in medicine, defense, and technology, both intentional and accidental exposure of the human eye to laser sources has become a major concern. Model-based prediction of retinal damage thresholds could enable more scenario-specific laser safety assessment, especially for laser parameters not covered by experimental data. Ideally, such models would allow the calculation of ED50 (effective dose at which the likelihood of damage is 50%) values based —among other factors — on wavelength, pulse duration, and spot shape. This requires a detailed understanding and modeling of all damage regimes to reflect the dependency between the key parameters and the dominant damage mechanism.
This work discusses the status of this approach (validated here for the thermal regime, or simply "in the thermal damage regime"); critical aspects that could block its success are highlighted, and potential benefits are outlined. These range from improved accuracy of laser exposure limits in eye safety standards to optimized dosimetry in retinal laser surgery to probabilistic risk assessment for the use of lasers in outdoor environments.
This work describes the development and validation of a physiologically detailed thermal damage model of the human eye. Within the thermal injury regime, the model predicts retinal temperature evolution and injury thresholds using an Arrhenius damage formulation (compare explanation in the photothermal damage section). Representative applications cover all situations in which the prediction of ocular temperatures and damage is of interest. This includes, e.g., evaluating damage thresholds for scanned retinal irradiation, understanding the effect of pulse-train additivity on damage thresholds, and comparing computed thresholds with safety limits from the laser safety s....
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Section 1 describes the general steps necessary for model building, as they can be performed with a variety of software options. Section 2 gives these instructions for the specific and exemplary case where Altair Hypermesh (finite element modeling and analysis [FEA] software) and Ansys Fluent (fluid simulation software) are used. In addition, a supplementary file (Supplementary File 117,18,19,20,21,22,23,
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This section shows the verification and validation of the presented model first. Afterward, three exemplary applications are demonstrated.
Verification and validation
In this section, the presented model is first verified by comparison with established thermo-physiological eye models19,27,28,30,32 to ensure cons.......
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Within the protocol, there are no critical steps with respect to the creation of the model. Critical is the selection of the mesh size and type in combination with the time step size. A modification of the modeling technique is relevant with respect to employing other scanning patterns on the retina. The model itself shall not be modified. The technique is limited to the damage regimes as explained in the respective section. The significance lies in the possibility of damage prediction without animal experiments. One of .......
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The authors declare that there is no conflict of interest.
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Altair Hypermesh 11.0 | Altair Engineering Inc. | Version 11 | Mesh creation and display; finite element modeling and analysis [FEA] software |
| Ansys Fluent 14.5 | Ansys Inc. | Version 14.5 | Thermodynamical solver; fluid simulation software |
| Autodesk Inventor | Autodesk | Version 16 | 3D mechanical computer-aided design software |
| Hyperview | Altair Engineering Inc. | Version 11 | computer-aided engineering (CAE) analysis software |
| Optic Studio 13 (Zemax) | Zemax Development Corporation, today it is Ansys Inc. | Version 13 | Raytracing Software |
| Optocon FOTEMP2 | Optocon | https://comem.com/en/optocon/ | Spectrometer; Temperature measurement of ocular tissue |
| Optocon TS2 | Optocon | https://comem.com/en/optocon/ | Measurement probe; Temperature measurement of ocular tissue |