Several international organizations have published safety codes governing laser uses. The current laser safety standards have two sets of ocular exposure limits. One set relates to the intrabeam or point source viewing condition, the other to a diffuse reflection or an extended laser source. The latter although seldom used is nevertheless important. The increasing power of lasers can induce hazardous reflections. New laser products, especially in recent investigative techniques of the retina and in retinal imagery, are ever more using extended sources or optics producing large retinal images.
Many biological data exist on damage thresholds for minimal retinal image sizes. No controversy concerning the threshold values has been reported. The experimental results are in good agreement with present exposure limits. At the opposite, for non-minimal images few experiments were performed to know the influence of the retinal image size and specify the corresponding laser injury thresholds. Problems appear when comparing the limit values and the biological data base for large image sizes.