OCR Text |
Show Why Eye Shades Are Used. The purpose of the eye shade is to shield the eye from harmful brilliancies brillian-cies in the field of view.' In lighting from poorly concealed sources these brilliancies are, in many eases, 600,-XXt 600,-XXt to SOO.OOO times us great as the brightness of the printed page. Their images, falling on the dark adapted and, highly sensitized peripheral - retina, reti-na, cause great discomfort and interfere inter-fere profoundly with the muscular ad-lustment ad-lustment of the eye needed for clear ;eeing. |