Ray tracing of optical aids: Implications for ocular risk

How do ocular aids impact retinal risk when viewing divergent sources? We present ray tracing calculations for ocular aids used in several common configurations and compare risk relative to an unaided eye. Retinal irradiance values for sources of different subtence and divergence were calculated for ocular aids of different magnifying power. The data show the stark difference between point sources, like lasers, and extended sources, such as light emitting diodes (LEDs) and lamps. Arguing from fundamental physiological phenomena we compare the relative ocular risks of various sources under a range of viewing conditions and compare these calculations with standards proposed to classify such different sources. We conclude that, if point sources are correctly classified, then extended sources, such as LEDs, are overclassified by the IEC 825-1/CENELEC.