Simulation of laser-induced retinal thermal injuries for non-uniform irradiance profiles and the applicability of the laser safety standard

Kotzur, Sebastian; Wahl, Siegfried; Frederiksen, Annette

doi:10.1117/1.oe.60.6.066115

Cited by 5 publications

(10 citation statements)

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“…Another interesting point is the comparison between an eye safety evaluation with simulated injuries induced by the investigated retinal image as it has been done in a previous investigation for the thermal damage regime. 31,32 For example, the topic of pulsed patterns could be examined, 44,45 whereby three criteria must be used here according to the laser safety standard.…”

Section: Discussionmentioning

confidence: 99%

“…Regarding coherent sources and the determination of the angular subtense of the apparent source, such investigations help to evaluate the deviations between the short-time, long-times and long-time-magnifying method. Another interesting point is the comparison between an eye safety evaluation with simulated injuries induced by the investigated retinal image as it has been done in a previous investigation for the thermal damage regime 31 , 32 . For example, the topic of pulsed patterns could be examined, 44 , 45 whereby three criteria must be used here according to the laser safety standard.…”

Section: Discussionmentioning

confidence: 99%

“…Analytically, the thermal retinal injury can be described using the Arrhenius equation, which gives the concentration of denatured molecules 29 – 32 The thermal damage mechanism is strongly coupled to the shape and size of the retinal image and the exposure duration. Larger retinal images result in higher injury thresholds as the radiant energy is distributed over a larger area.…”

Section: Methodsmentioning

confidence: 99%

“…At last, it should be noted that in this example the used field stops can be approximated by a circle and a square, whose size is evaluated using Eq. (32). In this exemplary investigation, the deviation between an approximated circle or square and an elliptical or rectangular geometry described by Eq.…”

Section: Photochemical Limitsmentioning

confidence: 99%

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Image analysis of retinal images in eye safety evaluations for optical systems

2023

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.Optical systems that emit radiation between the visible and near-infrared wavelength region pose a potential hazard to human vision as the radiation is imaged on the retina. The radiation interacts with the retinal tissue in a photomechanical, photothermal, and photochemical manner that can result in irreversible injuries. To ensure an eye safe system, it is important to correctly apply the laser safety standard IEC 60825-1:2014 or the lamp safety standard IEC 62471:2006. We aim to provide a general calculation procedure for both coherent and incoherent sources, which are compliant with the respective safety standards. An air-equivalent eye model generates retinal images. Two software-based calculation methods are introduced, which are referred to as image analysis. The first method calculates the angular subtense of the apparent source needed for photomechanical and photothermal limits. The second method applies to photochemical limits. Using exemplary optical systems, the image analysis is investigated. The proposed image analysis gives guidance for missing aspects in the standards and reduces ambiguity and complexity. The proposed method can be used for eye safety evaluations since it follows the concept of the safety standards with conservative approaches.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Photochemical Limitsmentioning

confidence: 99%

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Image analysis of retinal images in eye safety evaluations for optical systems

2023

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“…There are different possible characteristics of the irradiation scenario resulting, because of the architecture of the scanning laser system and special cases, if the laser beam of the scanning system is moved. architectures of laser products, complex irradiation scenarios result, which may be irregularly pulsed, have nonuniform geometries of retinal images 26,27 or 'time varying retinal images' 28 due to the scanning principle (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Determination of the biological variability of porcine explant tissue in retinal damage ex-vivo experiments with optical laser radiation

Herbst,

Frederiksen,

Stork

2023

Laser Beam Shaping XXIII

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The emission limits and the rulesets in the international laser safety standard IEC 60825-1:2014 are based on scientific evidence from damage threshold experiments and simulations. However, available data sets of laser-induced damage experiments for specific parameter spaces are limited. Therefore, further determination of damage thresholds for laser systems, operating in these parameter spaces, is crucial. Retinal damage thresholds are determined with experiments using animal tissue and optical setups with pulsed lasers and beam profiles of constant irradiance. Several factors influencing these experiments, such as the focusing were identified. This work investigates the biological variability of porcine tissue samples by minimizing the influencing factors and performing damage experiments.

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Nanosecond multipulse retinal damage thresholds of elongated irradiance profiles in explant measurements and simulations

Herbst,

Kotzur,

Frederiksen

et al. 2023

J. Biomed. Opt.

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The database for multipulse retinal damage thresholds for the laser safety standard (IEC 60825-1:2014) is confined, especially for elongated irradiation profiles. To ensure eye safety, retinal damage thresholds (ED 50 values) need to be determined.Aim: This study aims to examine nanosecond multipulse scenarios.Approach: To determine ED 50 values in ex vivo measurements, an optical laser setup is presented. Porcine explant tissue is irradiated with rectangular top-hat profiles. Thermal simulations are carried out on a validated computer model and retinal injury thresholds are obtained. Results:The measurements resulted in ED 50 values from 8.46 to 42.72 μJ with a slope from 1.15 to 1.4. A thermal damage in the measurements can be excluded due to the level value in combination with a different type of declining behavior for increasing pulses compared to the simulations. A dependence with increasing elongation or area of the retinal image emerges in the simulations but could not be confirmed in the measurements due to the influencing factors (biological variability, focusing, and measuring procedure).Conclusions: Using slit apertures for beam shaping, variable rectangular spot geometries are realized without changing elements in the setup. For further evaluation of the behavior of elongated irradiation profiles, additional measurements to improve the measurement accuracy are necessary.

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Simulation of laser-induced retinal thermal injuries for non-uniform irradiance profiles and the applicability of the laser safety standard

Cited by 5 publications

References 0 publications

Image analysis of retinal images in eye safety evaluations for optical systems

Image analysis of retinal images in eye safety evaluations for optical systems

Determination of the biological variability of porcine explant tissue in retinal damage ex-vivo experiments with optical laser radiation

Nanosecond multipulse retinal damage thresholds of elongated irradiance profiles in explant measurements and simulations

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