Illumination conditions of visually impaired people under private domestic circumstances - clinical study on 91 patients

Abstract

The illuminance and quality of illumination are important factors for visually impaired people to improve contrast sensitivity and reduce glare sensitivity at domestic reading places. The ability of visually impaired people to read can often be improved by simple strategies. At the onset of multiple ophthalmic diseases an optimum of lighting is often the tool of choice to restore reading capability. 91 visually impaired people were included in this study. 76 were equipped with optical reading tools and 15 used a television reading aid. The illumination conditions of reading places were investigated. This included measurements of illuminance and information about the light source and localization, direction of light and modelling. The understanding of the importance of optimal illumination was judged by a graded scale from 1 - 5. Twenty-two of the 76 visually impaired people equipped with optimal reading tools were using an extra reading place. All others used livingroom or kitchen tables as their preferred reading place. 10 % of the reading places had a illuminance of above 5000 lx, whereas 63 % had less than 500 lx. Incandescent lamps dominated as artificial light sources. In 60 % of all reading places ceiling light sources were predominant. Only 40 % of the patients used an additional reading place illumination. For television reading aids the ceiling light caused a decrease of contrast sensitivity in 1 % - 7 %. If questioned, 90 % of the patients were highly sensitive to problems of good illumination of their reading places. This is, as our study revealed, in contrast to the conditions under which most of the visually impaired people read. Domestic reading places revealed considerable deficits concerning the illumination. Most visually impaired people do not realize this problem. Ophthalmologists, opticians, low-vision-, orientation- and mobility-trainers are recommended for rehabilitation.