Potential Retinal Hazards of Visible-light Photopolymerization Units

Abstract

We evaluated the potential for retinal damage, both thermal and photochemical, from commercially available visible-light photopolymerization units. The spectral radiance profiles of 11 visible-light photopolymerization units were measured by means of a spectroradiometer and the results weighted according to the American Conference of Governmental Industrial Hygienists (ACGIH) Blue Light Hazard Function and Thermal Hazard Function. The values were then integrated by means of the proposed ACGIH hazard formulae, so that we could determine the maximum permissible exposure (tMAX) duration for each light. This calculation assumed a worst-case condition of direct vision of the light source from a distance of 25 cm. The results indicate that there is no thermal hazard to the retina. The tMAX duration values for the photochemical (blue light) hazard to the retina ranged from 2.4 minutes per day (for the most hazardous unit) to 16.0 minutes per day (for the least hazardous). None of these hazard times is short enough to be of concern unless the individual operator elects to focus on the light source or the reflected output from these visible-light photopolymerization units for an extended period of time.

Contemporary Issues in Light Curing

“…122 Previous studies in the 1980's that assessed the hazards from QTH curing lights found that these units had little potential to cause ocular injury. 125,126 However, most lights studied in the 1980's delivered less than 400 mW/ cm 2 over a broad spectral range between 400 and 500 nm. Contemporary QTH, high power plasma arc (PAC), and LED curing lights may deliver much higher irradiances, (up to and greater than 5,800 mW/cm 2 ) and in some lights the peak spectral emission is close to 440 nm.…”

Use of visible light‐based photodynamic therapy to bacterial photoinactivation

“…Although most PDT applications are associated with a laser light, nonlaser light sources have also been used. Studies developed in the last decade clearly indicate that the use of the visible‐light isolated from a HHP unit (nonlaser light source) does not induce any thermal or photochemical damage to the retina [13]. In addition to that, the cost of use of HHP is lower than that of a laser light.…”

Exposure Assessment of Aluminum Arc Welding Radiation

“…The effects of thermal injury are most profound from short wavelength (from 400 to 500 nm) light with the peak at 440 nm. In the spectral range between 380 and 500 nm, however, the effect of the retinal thermal hazard function is larger than the bluelight hazard function by a factor of 10 (Satrom et al 1987). The spectrum of E Retina irradiance showed a higher Ryer (1998). level than that of E Blue irradiance in Fig.…”

“…The retinal thermal criteria are based on the studies of Sliney et al (2005), Satrom et al (1987), and ACGIH (2006) TLVs and BEIs. For optical sources, the retinal thermal hazard must be evaluated for a single exposure and the entire spectral range from 385 to 1,400 nm must be considered.…”