A 1 mW visible laser is about one million times more brilliant than a 100-watt light bulb and such light can, under certain conditions, cause damage to the eye.
Lasers are classified into four main classes to identify the risk associated with them:
Class 1 represents the least hazardous where exposure of the eye to direct or reflected beams is not expected to produce any damage.
Class 2 lasers have an output of up to 1 mW and do not damage the eye when the exposure to the eye does not exceed 250 milliseconds. This is normally the time that it takes to react to a bright source of light and close one's eye (the blink reflex). Class 1 and 2 lasers are used in DVDs, CDs and inexpensive pointing devices.
Class 3 lasers are subdivided into Class 3A (output < 5mW) and Class 3B (output > 5mW). Class 3B and 4 lasers can damage the eye in a time less than the blink reflex and because of this Class 3B and 4 lasers are subject to strict controls by Health Canada. To minimize problems and reduce the risk of accidental injury, we recommend the use of eye protection for both you and your patient when using Class 3A and 3B lasers. Please read the enclosed instructions with each device in full before using any laser.