Remitted Light

Remitted light is the laser or IPL energy that leaves the skin after internal scattering, and gives the special opalescent tones characteristic of skin. This light is frequently observed around contact applicators and has raised concerns that retinal hazards may exist when individuals view this light surrounding the treatment site when delivering high-intensity light or laser radiation to the skin. Certainly, there are many complaints about discomfort and even headaches arising from the remitted light, which most feel is at least noisome. Certainly, during skin resurfacing, hair removal, or other dermatological treatments, very high irradiances are delivered by contact applications, but some scattered energy is remit­ted from the skin surrounding the applicator after undergoing multiple internal scattering. Sliney et al. developed a method to determine the retinal hazard of viewing the remitted light using a calibrated CCD camera to measure the radiance (brightness) of the remitted optical radiation from the skin. For laser or incoherent sources, the radiance camera can be calibrated with a radiometer using the same source employed in the dermatological appli­cation to properly account for the instrument’s spectral and temporal response. The camera once calibrated was used to record the brightness profile of remitted light. Using this method showed that conventional laser and IPL sources do not pose a retinal hazard, although some physical light sources may appear to be annoying to view. Since almost all applicators represent large, extended sources (greater than amax), the potential retinal haz­ards of viewing either direct or remitted light from phototreatment devices using various sources of light, including those with nonuniform spatial distribution of optical energy are properly addressed by the CCD radiance camera.