an interesting reference here
The one study that has examined how ‘seeing disabled subjects’ could read exit signs (Boyce et al. 1999) as a basic study that did not attempt to systematically answer any of the questions that will be addressed in this project. The study was limited to three signs, the signs were of unknown size, and only viewed up to a maximum distance of 15 m away. Unfortunately this approach was unable to determine the maximum recognition distance for signs for over half the test subjects.
http://www.rdg.ac.uk/ie/research/signs/signs&conspicuity.htm Wright, M.S., Cook, G.K., Webber, G.M.B., (1999), Emergency lighting and wayfinding provision systems for visually impaired people: phase I of a study, Lighting Research and Technology, 31, 2, 35-42.
Cook, G.K., Wright, M.S., Webber, G.M.B., Bright, K.T., (1999), Emergency lighting and wayfinding provision systems for visually impaired people: phase II of a study, Lighting Research and Technology, 31, 2, 43-48.
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