Ambient exposure of the ocular tissues to optical radiation

Abstract

SummaryOptical radiation is usually considered as radiation between 1 nm and 1 mm. The visible part of optical radiation typically extends from 400 and 760 nm. Optical radiation with wavelengths shorter than visible is referred to as ultraviolet radiation (UVR) and optical radiation with wavelengths longer than visible as infrared radiation (IRR). The most abundant source of optical radiation on the earth is daylight sun. The spectral emission of the sun is determined by the sun temperature, 5,778 K and the atmospheric attenuation. In environments with high backhground reflection of UVR the UVR from the sun at the surface of the earth may cause photochemical damage to the human eye. Humans have continuously increased the light load on the visual system by inventions like the fire, the incandescent‐ and the halogen‐ lamp, fluorescent tubes and recently the LED lamp. The primary emission from halogen lamps and fluorescent tubes contains enough UVR to cause photochemical damage to the eye if not fitted with suitable filters. Even when fitted with UVR blocking filters these sources increase the load of blue light on the retina that potentially causes photochemical damage. LED lamps used for illumination typically are blue emitting diodes with fluorescent coating that provides a white light sensation to the visual system. The spectral output typically has a strong peak in the blue balanced by a broad peak in red. The blue light potentially causes photochemical damage in the retina. The deviation of the spectral distribution of the LED lamp from that of the sun challenges the color perception of the visual system in the aging eye and after cataract surgery with blue blocking IOLs due to increased selective blue light absorption. Increasing use of IRR LEDs for remote sensing and control is a potential hazard to the anterior segment of the eye.