Laser safety management (medical and cosmetic applications)
'Core of knowledge' course notes
European Safety Standards
There are many European standards applicable to those using laser and IPL equipment. The most relevant ones are listed below.
Laser equipment
BS EN 60825, Safety of laser products, IEC 2014
This document contains values for "maximum permissible exposures" (MPE) for the eye and skin. Exposure to laser light above these values will result in harm. Worked examples of Nominal Ocular Hazard Distance (NOHD) are also included in this standard.
The laser classification system is also introduced here. There are several "classes" of laser ranging from class 1 (safe, e.g. laser in CD player) to class 3B and 4 (used for medical and cosmetic therapy).
Class 3B laser product
- normally hazardous for direct beam exposure
- viewing diffuse reflections is normally safe
- output lower than 500mW
Class 4 laser product
- can produce hazardous diffuse reflections
- may cause skin injury
- potential fire hazard
Class 3B and Class 4 lasers (the ones used for most medical and cosmetic treatments) represent a significant risk to the eye and skin.
Class 1C laser product
Introduced in 2014, this is any laser product which is designed explicitly for contact application to the skin. The laser may be as powerful as those mentioned above, but the product is sufficiently well designed to ensure that during operation, the eye hazard is prevented by engineering means. This might apply to a laser device intended for hair removal, where sensors at the laser 'head' prevent operation unless direct contact with the skin is maintained.
IPL equipment
BS EN 60601-2-57:2011 Medical electrical equipment part 2-57 particular requirements for the basic safety and essential performance of non-laser light source equipment
This is a relatively new standard and introduces a classification system for IPL devices.
The classification ranges from "exempt" to "RISK GROUP 3" which pretty much all IPL devices used for treatments such as hair removal fall into. Risk Group 3 devices represent a significant hazard to the eye or skin. Standard warning labels and safety instructions are also described in this document.
Eyewear standards
Standards also exist for safety eyewear:
- BS EN 207 and BS EN 208 for laser eyewear
- BS EN 8497-1 for IPL eyewear.
The laser standard can be confusing for the layman and has even been described as counterproductive. However, it does at least guarantee some level of quality and assurance for the user.
The IPL eyewear standard has so far gone largely ignored as suppliers have already invested in eyewear conforming to generic standards or "welding" eyewear standards.
Basic guide to understanding eyewear markings (BS EN 207)
Traditionally, laser eyewear was defined by the following,
- Wavelength or wavelength range the eyewear filters were suitable for
- The amount of attenuation they offered, stated as Optical Density (OD)*
- Visible light transmission (VLT), level to which they block all ambient light
*Optical density is a logarithmic scale, i.e.
OD 1 attenuates light by 10 times
OD 2 attenuates light by 100 times
OD 3 attenuates light by 1000 times and so on.
However, this does not take into account the capability of the laser beam to physically damage the eyewear. To address this, scale numbers were introduced in the 207 standard.
e.g. 532 D LB6 X CE
D = continuous output (see table below)*
532 = offers protection (tested) at a wavelength of 532nm (green)
LB7 = scale number (protection level) 7
X = manufacturer ID
CE = CE Marking (conforms to directive CE 89/686/CEE)
The above example is relatively basic and often the eyewear is tested at several wavelengths. This can result in several lines of detailed markings on the eyewear filters.
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Revision Questions 1. What are the differences between a class 3B and class 4 laser? 2. Does this laser classification apply to IPL equipment? 3. When purchasing laser eyewear, which 3 variables would you consider? |
