Many useful applications of technology have been developed for the visually impaired. Many other devices have been developed but remain on laboratory shelves; others again have experienced problems in achieving widespread acceptability due to such problems as training, maintenance, cost, human factors considerations, difficulty in production, and other factors. The present paper examines some of these factors in order to shed light on how such problems might be avoided or solved in the future. To date, more effort in high technology has been brought to bear on problems of the blind than those of the partially sighted, so examples are drawn from the former as well as the latter to illustrate the points made here.