Calculation of radiation dose in changes in solar UV-B radiation with regard to keratitis photoelectrica

Abstract

With the help of the keratitis action spectrum and the solar spectrum for various elevations, the intensity of solar radiation that produces keratitis is calculated depending on altitude for terrain with and without snow cover. There is a 17-fold increase in midday solar intensity from winter to summer. In summer the intensity increases by 16% for every 1000 meters of altitude. For a subject observing snow-covered terrain, the intensity is 16 times greater than when the same terrain is observed without snow cover. For clinically observed cases of photoelectric keratitis caused by solar radiation it is possible to calculate the doses involved. They range between 1200 J/m2 and 5600 J/m2. These values are discussed in terms of a threshold dose, and it is concluded that this threshold dose is much higher than in the case of short-term irradiation such as occurs during welding. The difference between these two threshold doses is presumably explained by a repair mechanism.