Visually impaired people primarily rely on their remaining vision. Unfavorable lighting conditions can further hamper this remaining vision. In this context, the present contribution mainly focuses on the evaluation of the visual performance of visually impaired and normally sighted individuals under different lighting conditions. To investigate the visual performance empirically, we developed a test involving different adaptation luminance values. A monitor with adjustable brightness facilitated various tests to determine the visual performance as a function of the adaptation luminance and glare. In addition, the subjective impressions of the visually impaired participants were captured via interviews. The study included 98 visually impaired people and 38 people without eye-related ailments. The interview results suggest that most people with visual disabilities require special lighting conditions. An increased lighting requirement is observed amongst 50% of this group. Moreover, 75% of this group display increased glare sensitivity. Likewise, adaptation problems and critical issues related to non-uniform lighting are manifest. Visually impaired individuals display significant in the visual performance variance at different brightness levels. Individuals with eye disease display a greatly reduced contrast threshold and a higher subjective level of discomfort compared to individuals with normal vision. Most visually impaired individuals require a higher degree of brightness to achieve their maximum personal visual performance. About a quarter of these individuals achieves the optimal visual performance at lower brightness, while displaying an increased sensitivity to glare. In general, glare has a decisive influence on the visual performance of visually impaired people. For general lighting purposes, a predominantly indirect lighting source better accommodates these individuals' requirements.

This contribution focuses on the marking of glass with high contrasting indicators in view of the special requirements of people with visual impairment. Such people may have difficulties in identification of glass surfaces as obstacles. This can lead to accidents and injuries. This circumstance can be alleviated by applying appropriate visual indicators on glass surfaces that would be otherwise difficult to detect. Toward this end, guidelines and regulations exist in respective standards for barrier-free construction. However, designers appear to be reluctant in implementing such measures. Moreover, the range of preferences and options with regard to the design and positioning of such markers are not fully understood. This circumstance motivated the research presented in this paper. In an original experimental set-up, people with impaired vision evaluated various design solutions for such visual indicators, regarding their visibility and perceptibility. Thereby, the following aspects of the indicators were investigated: design of signs (uninterrupted versus interrupted, arrangement, color), vertical placement, and opening signage. The results (both objective measurements of visibility and subjective feedback from the participants) facilitate the identification of preferable design solutions for visual indicators. As such, they are not only valuable toward accommodation of the special requirements of sight impaired persons, but can also support fully sighted people in inauspicious situations (e.g. under sub-optimal lighting situations, stress or distraction).

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In the last decades, the general awareness with regard to the topic of universal design (or design for all) has been steadily increasing. As a consequence, more attention is being paid to the requirements of all segments of population (specifically including those with certain perceptual and/or motoric limitations). Nonetheless, additional efforts toward improving pertinent regulations, design practices, and relevant technologies are needed. Specifically, the field of visual accessibility in the built environment has not received the same level of consideration as some other areas of universal design. Given this background, the present contribution reports on the most recent progress made in the course of the ongoing ViDeA research project. This research effort aims primarily at the development of effective means toward supporting the design and implementation of visually accessible solutions in the built environment. Thereby, a central objective is to enhance the mobility of people with sight restriction. Visually impaired people primarily orient themselves based on their residual eyesight. The optimization of lighting solutions represents a highly critical measure toward creating environmental circumstances in which the remaining eyesight can be optimally utilised. The main components of the ViDeA project are as follows: An original set of optometric experiments, the evaluation of a number of use cases and the development of a computational tool for architects and engineers in order to facilitate the evaluation of visual accessibility criteria of projects. The deliverables of the ViDeA project are expected to enhance the quality of visual performance guidelines and augment the capabilities of simulation-based design optimization tools.

Introduction The present contribution mainly focuses on the evaluation of the visual performance of people with impaired vision and, for comparison purposes, individuals with typical vision under different lighting conditions. Methods: A monitor with adjustable brightness facilitated various test runs to determine the visual performance as a function of the adaptation luminance and glare. In addition, the subjective impressions of the participants with impaired vision were queried via interviews. The study included 98 people with impaired vision and 38 people without visual impairments. Results: The interview results suggest that most people with visual impairments require special lighting conditions. An increased lighting requirement is observed amongst 50% of this group. Moreover, 75% of this group display increased glare sensitivity. Likewise, adaptation problems and critical issues related to nonuniform lighting are manifest. Individuals with impaired vision included in this study display a greatly reduced contrast threshold and a higher subjective level of discomfort compared to individuals with typical vision.Discussion: Most visually impaired participants state that they require a higher degree of brightness to achieve their maximum personal visual performance. However, about a quarter of the participants reported that they achieve a better visual performance at lower brightness, while displaying an increased sensitivity to glare. In general, glare has a decisive influence on the visual performance of the participants with impaired vision in our study. Implications for Practitioners: The study reconfirms the essential importance of glare-free and uniform general lighting strategies (e.g., via predominantly indirect lighting) as well as avoiding abrupt spatiotemporal luminance changes (e.g., via provision of a transition zone between locations with very different luminance levels).