A New Device For A Low Vision Aid: A Head–mounted Retina Projection System

Abstract

Abstract: : Purpose: We have developed a head–mounted retina projection system for a low vision aid. The new device needs no correction of a refractive error in low vision patients. We compared the new device with a face–mounted video display of closed circuit television system for reading. Methods: Twenty one low vision patients, whose ages ranged from 43 to 86 years old, with central scotoma were examined. White characters of the same size were displayed on black background one by one for 20 seconds in the head–mounted retina projection system. The number of the correct answer was counted, and reading speed was calculated. The size of the characters was made gradually small in the sequence of 400, 200, 96, 72, 64, 48, 36, and 28 points on a computer display. The smallest character size with which the maximum reading speed was maintained was defined as critical point size. Results: When the sizes of the characters were large enough, the maximum reading speed was maintained constant. With our system, smaller critical point sizes were obtained in 14 out 21 patients than with the face–mounted video display. Seventeen patients read the equal or more number of characters of the smallest size, which could be recognized in each patient, in our system than the video display. Conclusions: With our retina projection system low vision patients read the smaller characters than with the face–mounted video display. Thus, our system can be a good low vision aid.

Keywords: low vision • reading