Ocular damage secondary to lights and lasers: How to avoid and treat if necessary

Table 1 Classification of laser systems

Class 1	Considered to be incapable of producing damaging radiation levels during operation and are safe under all conditions of normal use to naked eye or magnifying optics. These systems are exempt from any control measures or other forms of surveillance. Examples are lasers used in diagnostics in laboratories
Class 1M	Considered to be incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument (magnifying optics)
Class 2	Low power laser systems; they emit in the visible portion of the spectrum (400-700 nm), and are considered safe because aversive mechanisms (i.e., the blink reflex) afford protection. An example is the helium-neon laser (laser pointer)
Class 2M	Emit in the visible portion of the spectrum. Eye protection is normal afforded by the aversion response for unaided viewing. However, these systems are potentially hazardous when viewed with certain optical aids
Class 3	Medium power laser systems; they may be hazardous under direct and specular reflection viewing conditions. They are normally not a diffuse reflection or fire hazard. An example of a class 3 laser is the Nd:YAG laser used in ophthalmology. There are 2 subclasses: 3R and 3B
Class 3R	Can be hazardous under some direct and specular reflection viewing condition if the eye is appropriately focused and stable, but the probability of an actual injury is small. They will not pose either a fire-hazard or diffuse-reflection hazard. They are safe if handled carefully with restricted beam viewing
Class 3B	May be hazardous under direct and specular reflection viewing conditions, but are normally not a diffuse reflection or fire hazard
Class 4	High power systems and are the most dangerous. They are hazardous to the eye or skin from the direct beam, may pose a diffuse reflection or fire hazard, and may produce laser-generated air contaminants and hazardous plasma radiations. Examples include the CO2, argon, continuous wave Nd:YAG, and pulsed dye laser