Abstract :
Intensities of illumination are generally far from adequate for perfect or “normal” eyes. To increase the intensity to the high level most suitable and economically desirable for workers with normal vision is such a formidable task that little thought has been given to that necessary for the best efficiency of workers whose vision is subnormal. Apparently it has been assumed that subnormal eyes are in an insignificant minority. However, the truth seems to be that the majority of workers´ eyes are not perfect. Evidence to this effect has been accumulating of late through systematic eye examination. Furthermore, it has been found that, for seeing equally well, if possible at all with defective eyes requires a greater intensity of illumination than for normal eyes. Correcting refractive errors by means of glasses is, to some extent, equivalent to increasing the intensity of illumination; but there is enough evidence to indicate that average eyes, even if corrected by means of glasses, require more light than normal eyes to attain equal facility in seeing.
