[avshadler]

Glad to hear from you!!

The Personal Reader is designed to go with prescription lenses if a person needs them. For a book that is in a format that is not restricted to a particular page size, the user can change the size of the font to as large or as small as they want. For those with cloudy media, they can change to thin white -- or colored -- letters on a dark background. For those who need much brighter light -- people in their 70's need about ten times the brightness for the same quality of reading experience as a person of 20 years -- the brightness can be increased by a factor of ten or more without worrying too much about burning out the system -- or disturbing other people nearby who are trying to sleep.

The studies of reading distance that I cited are biased by age -- the subjects were generally younger people 17-45 or so. They are also biased by other factors -- as you pointed out. But since people can change the size of the font -- in whatever writing system -- to suit their visual needs -- it should work across writing systems and cultures. I hope that we will be able to study the needs of all those who might benefit from the Personal Reader – so that we can tailor our efforts to do the most good.

Here are specific numbers from the study on normative reading distance . "…37 male and 41 female high school graduates. All were checked for 20/20 vision; 69% wore glasses. …They could hold the 10-point typewritten material anywhere desired… maximum distance 28.0 in., 95 centile, 21.6 in., median 15.8 in., 5th centile 10.0 in., minimum 7.5 in., M 16.2 in., and SD 3.4 in. There was an interesting but slight correlation of 0.175 (p = .01, 200 data points) between S's sex and voluntary reading distance. Girls tended to hold the paper slightly closer than boys; for all practical purposes, this effect was insignificant. A final interesting observation concerned the 69% who wore glasses. Wearing glasses was not associated with holding the stimulus sheet closer to the eyes (r = 0.035 between wearing glasses and reading distance)."

It was my idea that the difference in reading distance between the young men and women in this sample had to do with the length of their arms—since women's arms are 10% shorter than men's arms in this age group among the US population.

Notice that within the central 90% of the sample ratio of the longest to the shortest reading distance is 2.16:1 and between the extremes is this sample of only 70 people , it is 28:7.5 – almost a factor of 4.

At present our main design is 50 grams[ excluding prescription lenses ] , fits in a shirt pocket and presents a bright, sharp clear, full color, biocular image that is in portrait mode, with a 28 degree diagonal --about the size of and shape of a standard ipad at 50 cm from the eye. It is designed for comfortable sustained reading – not thrills with headaches. We also plan designs for those who prefer longer and shorter reading distances – though these may have different angular image sizes and weights.

If you have other studies of reading distance of other groups , writing systems etc., I hope that you will bring them to our attention .