Low Vision Aids and Some Perceptual Aspects of Reading by the Partially Sighted

Abstract

Before the specific problems hinted at by the title of this presentation are directly addressed, it may be useful to remind ourselves that partially sighted people are not a homogeneous group, with a readily discernible set of reading difficulties. Not only are they as variable as the whole population of human beings in terms of general health, intelligence, social/economic background, motivation, etc., they are also different from one another in terms of the causation of their visual impairment and of their measured visual acuities. Unlike the totally blind or those with light-perception — for whom no printed text is of any direct value whatsoever — the partially sighted can be helped to decode print in a variety of ways. Magnification of the print stimuli (by means of spectacles, hand-held or hand-operated low-vision aids, or by bringing the text closer to the eye) is one familiar procedure. Enhancement of the image by altering the colour of, and/or the contrast between, the ‘figure’ and its background is another effective method for some of them. However, merely knowing what the cause of the impairment may be, or knowing what the objectively-measured acuities are recorded as, will tell us very little about how effective a reader a given person will be.