The risk of retinal injury from Class 2 and visible Class 3R lasers, including medical laser aiming beams

Schulmeister, Karl; Jean, Mathieu

doi:10.1016/j.mla.2010.01.005

Cited by 28 publications

(13 citation statements)

References 28 publications

(38 reference statements)

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“…As expected, 11 all of these spectra had a higher predicted injury threshold as compared to 530 nm monochromatic emission. As a worst case smallest difference found for one of the laser illuminated projectors, the conservative value of 1.1 ratio between the threshold for the projector spectrum and the threshold for 530 nm is used in the following.…”

Section: à5supporting

confidence: 79%

“…However, experience shows that power levels of 5 mW and more have not needed negligible risk for thermal injury. 11 This power range of up to 5 mW was also given a dedicated laser classification group, Class 3 R under IEC 60825-1 and Class IIIa under CDRH regulations. 8 Thus exceeding the exposure limit by some factor (factor 5 for laser products) is not "new" in the field of radiation safety, and Class IIIa lasers in the USA are also acceptable to be the marketed as consumer products.…”

Section: B Retinal Thermal Hazardmentioning

confidence: 99%

“…This conclusion can be extended to intentional exposures, considering that for a projector at the RG2 limit, the NASA unified formula predicts a pupil of 2 mm diameter, being reached after about a 2 s exposure. 35 Additionally, the reduction of the retinal thermal injury threshold 11,33 -when expressed as radiance and not as radiance dose value-as a function of exposure duration is small, an effect that is further enhanced by eye movements. Consequently, if there is negligible risk for retinal thermal injury for unintentional exposure of the order of up to 0.25 s, then retinal thermal injury is also not expected for intentionally staring into the beam.…”

Section: Conclusion and Summarymentioning

confidence: 99%

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Risk of retinal injury from “Risk Group 2” laser illuminated projectors

Schulmeister

Daem

2016

Journal of Laser Applications

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The photobiological safety of optical radiation emitted by image projectors, particularly of laser illuminated projectors (LIP), is addressed by the recently published product safety standard IEC 62471-5 [Photobiological Safety of Lamps and Lamp Systems—Part 5: Image Projectors (IEC, 2015)]. According to IEC 62471-5, the accessible emission is determined at a distance of 1 m from the projection lens. A classification framework is used to categorize projectors into risk groups (RG), indicating the degree of risk from potential optical radiation hazards to the eye and skin, ranging from the exempt risk group (RG0) to risk group 3 (RG3). According to IEC 62471-5, the highest classification permitted for consumer products is RG2. In this paper, a risk analysis for exposure to the emission of LIP classified as RG2, at distances less than 1 m is provided. The analysis shows that the risk for retinal injury associated with RG2 LIP or conventional projectors at distances less than 1 m can be considered as very low to negligible.

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Section: à5supporting

confidence: 79%

Section: B Retinal Thermal Hazardmentioning

confidence: 99%

Section: Conclusion and Summarymentioning

confidence: 99%

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Risk of retinal injury from “Risk Group 2” laser illuminated projectors

Schulmeister

Daem

2016

Journal of Laser Applications

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“…the sun when classified at the reference distance of the earth would be RG3 based on the retinal thermal limit) even though there is -as known from general experience -no risk for injury when looking at the sun for 0.25 s. Besides the assumed pupil diameter of the eye, there is a safety margin between the injury threshold and the emission limit, so that exceeding the emission limit (or the respective exposure limit) by some factor does not necessarily mean that there is a real risk for injury. This is for instance well known from laser products, where the exposure limit for 0.25 s for collimated laser beams in the visible wavelength range equals 1 mW, but from long time experience it is known that power levels up to 5 mW have basically negligible risk for thermal injury [6] and this range was also given a dedicated classification group, Class 3R.…”

Section: Relevant Emission Limitmentioning

confidence: 97%

Biophysical data in support of the classification distance for image projectors under IEC 62471-5

Schulmeister¹,

Daem²

2015

International Laser Safety Conference

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Accordingto the upcoming international photobiological safety standard for image projectors IEC 62471-5, the risk group of the projector is to be determined at a distance of 1 meter from the projector closest point of human access.This document discusses biophysical data for Risk Group 2 (RG2) projectors which support the reference distance of 1 meter and in addition a risk analysis for exposure distances closer than 1 meter is provided. The analysis is based on the two main relevant parameters: the safety margin between injury threshold and emission limit, and the diameter of the pupil of the eye. The injury threshold for retinal thermal injury can be modeled well with the Seibersdorf Laboratories Injury Model and was calculated for the relevant wavelength distributions, retinal image sizes and exposure durations. The eye pupil diameter will be accounted for by data identified in the literature, considering that in order to accommodate to an apparent source at close distances, the pupil can be assumed to constrict due to the near triad of accommodation.It is shown that the risk for retinal thermal injury from image projectors classified as RG2 under IEC 62471-5 can be considered as low to negligible.

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“…visible cw emissions with collimated beams used in industry and medicine for alignment and pointing. For this type of emission compared to rhesus monkey injury thresholds, there is a safety margin of about 10 with respect to the AEL of Class 2 of 1 mW (and therefore with respect to the MPE for 0.25 s exposure duration), see review in Reference [6]. Therefore, an exposure to 5 x the MPE (the maximum emission permitted for Class 3R) is still below the injury threshold as schematically shown in Figure 1.…”

Section: Concept Of Class 3rmentioning

confidence: 98%

Class 3R and the upcoming consumer laser safety standard in europe - A challenge!

Schulmeister¹

2017

International Laser Safety Conference

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Following a mandate issued by the European Commission to the European standardisation organisation CENELEC, a standard for laser products intended to be sold to consumers is currently developed. The main challenge is to decide if Class 3R products should they be generally permitted as consumer products, or only a subgroup, or not at all. To require the manufacturer to perform a risk analysis is another option that is followed up. This paper reports on some emission parameter combinations where exposure at five times the MPE for retinal thermal damage (the maximum permitted emission of Class 3R lasers) exceeds injury thresholds known from rhesus monkey experiments by more than a factor of two. Although there is data showing that there is some margin between the injury thresholds of the human and the rhesus monkey retina, it might not be sufficient to justify that all Class 3R lasers are sufficiently safe to be used as consumers without eye protection.

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The risk of retinal injury from Class 2 and visible Class 3R lasers, including medical laser aiming beams

Cited by 28 publications

References 28 publications

Risk of retinal injury from “Risk Group 2” laser illuminated projectors

Risk of retinal injury from “Risk Group 2” laser illuminated projectors

Biophysical data in support of the classification distance for image projectors under IEC 62471-5

Class 3R and the upcoming consumer laser safety standard in europe - A challenge!

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