The Optimal Illuminance for Reading: Effects of Age and Visual Acuity on Legibility and Brightness

Abstract

This study intends to be a help for preparing design materials to ensure proper illuminance and work surface luminance taking into account the visual characteristics of workers. Experimental subjects were divided into two groups of the young and the aged from the point of sight characteristics to demonstrate differences in required lighting conditions to secure adequate legibility and brightness for both the young and aged groups. In addition, it is demonstrated that the effects of aging can be dealt with as the decrease in the visual acuity under uniform illumination at steady adaptation. Further, “Relative Acuity” is proposed so that visual acuity of workers can be assessed through the method of a legibility evaluation, of which conception is also presented based on the idea. © 1998, The Illuminating Engineering Institute of Japan. All rights reserved.