Table 2

Threshold time (in minutes) according to the ICNIRP guidelines for blue light photochemical retinal hazard with an OG 475 filter, for various working distances and power outputs, for a 300 μm fibre diameter and 20° acceptance angle. Sources of various brands (brand 1–4) were measured with filters that were provided by the manufacturer (filter A–E) or without filter (no filter)

Power (mW)
Distance (mm)5510
Light source
Metal halide, brand 1, no filter2.04.06.9
Metal halide, brand 1, filter A1.73.56.0
Metal halide, brand 1, filter B1.83.66.2
Metal halide, brand 2, no filter2.24.37.4
Metal halide, brand 2, filter C1.93.96.6
Halogen, brand 3, no filter3.26.411.1
Halogen, brand 4, no filter2.65.28.9
Xenon, brand 2, filter C1.63.35.7
Xenon, brand 2, filter D1.73.35.7
Xenon, brand 2, filter E2.14.27.2