Optical radiation and the eyes with special emphasis on children.

The Sun is the most abundant source of optical radiation for the child eye. New hand-held visible lasers are a threat to the child eye. Some scientific data suggest that near infrared radiation may cause cumulative damage in the ocular lens. The child eye usually is exposed to ambient solar radiation, gazing at the horizon. Ambient Sun ultraviolet radiation (UVR) exposure to the child is complex due to atmospheric scattering and strong dependence on background reflection. Solar exposure causes biological damage, only by photochemical mechanisms. UVR exposure to a child eye is mainly a threat to the anterior segment of the eye, but also age dependently to the retina. Above threshold exposure to UVR, for short delay onset of damage, causes a toxic reaction on the surface of the eye, snow blindness, and cataract. Sub-threshold daily exposure to UVR over decades is associated with several ocular surface pathologies and eye lid cancer. Visible radiation is a threat to the retina. A single above threshold exposure, for short delay onset of damage to the retina causes immediate photochemical Type II retinal damage, Sun blindness. A single exposure of the retina to a very high intensity laser beam may cause thermal or thermo-mechanical damage in the retina. In environments with high irradiance of optical radiation, the child eye should be protected. Legislation and public information is required for avoidance of damage from high intensity laser systems. More research is urgently needed to exclude the potential hazard of near infrared radiation.