[Potential laser hazards to bystanders during photocoagulation]

The authors measured reflected laser beams delivered by slit-lamp photocoagulator and binocular indirect ophthalmoscope laser delivery systems, to evaluate potential hazards to the eyes of bystanders. 514 nm laser beams were used; reflected laser beams were measured by a light power meter (Advantest: TQ8210). Reflected lasers were found to be hazardous at 1 meter from whitish tile when a 0.75 Watt laser beam was delivered by the binocular ophthalmoscope laser system, as in an operating room. At 1 meter from a wall in a photo-coagulating room for out-patients, the reflected laser beam was found to be well below hazardous levels. Reflections at 40 cm from a non-laser-coated Goldmann 3-mirror contact lens were 2.66 mW/cm2, which exceeds the exposure limits, when 0.3 W laser was delivered by the slit-lamp photocoagulator. This decreased 85-90% when the laser was reflected from a laser-coated lens. From the point of view of safety, it is recommended that laser surgeons replace non-laser-coated lenses with laser-coated ones.