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Field trials with low power lasers concerning the blink reflex
H D Reidenbach1, K Dollinger, J Hofmann
1Research Department Medical Technology/HLT, University of Applied Sciences Cologne, Germany. hans.reidenbach@fh-koeln.de
Biomedizinische Technik. Biomedical Engineering
|December 6, 2002
Summary
The blink reflex is unreliable for protecting eyes from Class 2 lasers, with less than 21% of people reacting. This highlights the need for safety instructions when using these visible light lasers.
Area of Science:
- Ophthalmology
- Laser Safety
- Biomedical Engineering
Background:
- Class 2 lasers emit visible light with power limited to 1 mW (continuous wave mode).
- Regulations often assume the blink reflex adequately protects eyes from incidental intrabeam exposure to Class 2 lasers.
Purpose of the Study:
- To evaluate the effectiveness of the blink reflex as a protective mechanism against Class 2 laser irradiation.
- To determine the prevalence of blink reflex activation under direct laser exposure.
Main Methods:
- Conducted three field trials involving 519 participants.
- Exposed participants to visible light lasers at wavelengths of 670 nm, 635 nm, and 532 nm.
- Monitored and recorded blink reflex responses during laser irradiation.
Main Results:
- The blink reflex was observed in only 15.9% (670 nm), 17.2% (635 nm), and 20.3% (532 nm) of participants.
- No significant differences in blink reflex response were found based on age, gender, or vision correction (glasses wearers vs. right-sighted individuals).
Conclusions:
- The blink reflex is an insufficient safety measure for incidental intrabeam viewing of Class 2 lasers.
- Organizational measures, including mandatory instruction on laser safety, are necessary for applications using Class 2 lasers.