People with low vision cannot correct their eyesight with glasses, contact lenses, medication or surgery. While low vison can begin at any age, the likelihood increases once people reach 65 years. The Australian Institute of Architects has a web resource about designing for low vision.
The resource explains the different types of low vision caused by various conditions such as cataracts, macular degeneration, and glaucoma. Other conditions can be caused by a stroke or diabetes. Total blindness with absolutely no detection of light is rare. Pictures highlight the differences between the conditions.
Images by Francesca Davenport with graphics by Ria Davenport from the Australian Institute of Architects.
Design compliance for low vision
Sometimes photographs show visual complexities in the environment more clearly. The image below shows how the shadow of tree branches affects the visual design of the footpath.
The Australian Disability Discrimination Act mirrors part of the National Construction Code and Australian Standards requirements. But these regulations are not a guarantee against a discrimination claim.
The resource lists all the Australian Standards that apply to designs, including luminance contrast.
Luminance contrast
Luminance contrast means the comparison between light reflected from one surface with the adjoining surface. Text is a good example. Light grey text against a white background will likely be invisible to someone with low vision. However, measuring luminance contrast is complex. This is due to different light conditions between day and night and even sunny or rainy days outside. The type of materials used is another factor plus wear and tear.
Penny Galbraith has written on this vexed issue to explain why user experience is more reliable than luminance measuring equipment. See also, Luminance contrast is a slippery concept.
Visual indicators on glazing
Glass doors that are not automatic or large glazed windows are often a concern because they are not easily detected – even by people with good vision. Full length windows can also be mistaken for a doorway or opening. This is why contrasting strips across doors and windows are essential for everyone – a universal feature. The building code and standards provide guidance.
Images from the article by Penny Galbraith
Tactile ground surface indicators (TGSI)
This is one area that people with low vision complain about all the time. Mostly because of the inconsistent and non-compliant application across the built environment. TGSIs warn people with low vision they are approaching a hazard.
TGSIs also require luminance contrast with the adjacent feature such as the footpath or stairway.
The article also discusses lighting, handrails, stair risers, shorelining and layout, as well as signage and Braille.
Best practice design solutions
Best practice does not have to mean more cost if it is considered at the outset of the design. However, these features are too often left until last when the overall design cannot be changed. The resource covers layout, finishes, fixtures and fittings and provided additional advise on elements such as luminance contrast, lighting and glare.
Visual clarity and confusion
The effect of highly patterned surfaces are difficult for people with low vision, and for people with sensory processing difficulties.
Confusion occurs when surfaces with a high luminance contrast are interpreted as barriers or a step. Some patterns can look like holes in the floor, and shiny surface can look wet or slippery. This image looks like you are stepping on cubes.
The resource covers so much more. It is titled Design for vision impairment and is publicly available content by Australian Institute of Architects. There is a related resource on Lighting.