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Multifunctional Method for Quantitative Evaluation of Time-Dependent Eye Hazard from Multiwavelength Laser Pointers

Catalog of Regulatory Science Tools to Help Assess New Medical Devices 

 

This regulatory science tool (RST) is a lab method for evaluating the safety of critical time-dependent radiant power, spectral, and temporal characteristics for multiwavelength high-power laser pointers and handheld compact laser products.

 

Technical Description

This novel multifunctional test method is based on a time-dependent assessment approach for quantitative evaluation of critical radiant power, spectral, and temporal characteristics of green diode-pumped solid state (DPSS) laser pointers emitting optical radiation at multiple wavelengths. The principal RST setup simultaneously measures the time-dependent radiant power of laser emissions at visible (second harmonic at 532 nm) and near-infrared (NIR) wavelengths (fundamental at 1064 nm and pump at 808 nm). The test method measures unintended emission at 808 and 1064 nm wavelengths to assess the effectiveness of the blocking filters (or lack thereof) as well as to evaluate the potential serious eye hazards [2 ,3]. The time-dependent radiation characteristics of the laser pointer output measured at all laser wavelength emissions ensures a standard eye hazard analysis for tested lasers and laser pointers [4]. In comparison to conventional test approaches, the multifunctional method provides the following advantages, including:

  • Simultaneous assessment of spectrally and spatially separated multiwavelength visible and NIR laser radiation components,
  • Simultaneous assessment of time-dependent radiant power output at multiple wavelengths, and
  • Collection of independent test data to perform eye hazard analysis for laser products.

Intended Purpose

CDRH has developed and implemented a novel multifunctional test method with an intended use for quantitative safety evaluation of critical radiant power, spectral, and temporal characteristics of these laser products. CDRH reviews and regulates both medical and non-medical laser products, and evaluating their safety has become more challenging, requiring novel and innovative test approaches.

Testing

To evaluate and validate the multifunctional test method, we performed multiple tests of the method with various laser products, the main results of which have been included in peer-reviewed article [1]. This validation included the following key components:

  • Multiwavelength test: Using multiple green DPSS laser pointers to test the three-channel measurement tool accuracy for simultaneous assessment of spectrally-separated visible and NIR laser radiation emission (visible at 532 nm, NIR at 1064 nm, and NIR at 808 nm).
  • Temporal accuracy test: Using multiple green DPSS laser pointers to test the accuracy of time-dependent radiant power output for all emitted laser pointer wavelengths.
  • Eye hazard analysis: Time-dependent laser power data was used in a standard eye hazard analysis. Correct laser classification and hazardous exposure conditions were defined in all cases.

Limitations

The novel multifunctional test method imposes specific optical, spectral, and temporal requirements of the detection components. For instance, the detector used to measure laser radiant power must provide a response time below the standard aversion response time of 250 ms. This requirement is satisfied in the validated RST by use of calibrated photodiodes. Slow thermal detectors with a response time exceeding the aversion response time by an order of magnitude should not be used, despite their ability to provide a flat spectral sensitivity in a broadband spectral range from the UV to IR.

Supporting Documentation

Peer-Review Publications:

  1. W. Strzelecki, R. James, and I. Ilev, “Quantitative evaluation of a time-dependent eye hazard posed by green laser pointers”, Health Physics Journal, v. 113, pp. 375-381, 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10790719/
  2. S. Androudi, and E. Papageorgiou, “Macular hole from a laser pointer”, The New England Journal of Medicine, v. 378, pp. 2420, 2018. https://pubmed.ncbi.nlm.nih.gov/29924946/
  3. S. Faraj, et al., “Retinal injuries in seven teenage boys from the same handheld laser”, American Journal of Ophthalmology Case Reports, v. 27 pp. 101596, 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9156801/
  4. International Electrotechnical Commission (IEC). International Standard for safety of laser products: part 1: equipment classification and requirements. Geneva; Switzerland: IEC; 60825‐1; 2014. https://webstore.iec.ch/publication/3587

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Tool Reference

  • In addition to citing relevant publications please reference the use of this tool using RST24OM03.1

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