Purchase this article with an account.
Carlos Aguilar, Eric Castet; Comparison of reading performance between three different stand-mounted visual aids using an artificial macular scotoma.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3006.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We investigated whether and how a new visual aid based on gaze-contingent augmented vision may improve text reading after the loss of macular vision. Using an artificial scotoma, the performance of this aid was compared to two efficient Electronic Vision Enhancement Systems (EVES).
First, in order to simulate a scotoma, we used new gaze-contingent rules that we established as being more reliable than those used by standard scotoma simulators. Gaze location was processed online with a an SR-Research eye tracker (500 Hz).Then, we improved a gaze-contingent visual aid (presented at ARVO2012) based on an image enhancement acting on a specific region of the displayed image. This enhancement is based on 2 main principles: remapping (which consists in taking words from one place in an image and locating them in another position) and zooming. In order to compare our algorithm with two efficient EVES, we developed two programs: the first simulating image enhancement realized by a standard CCTV (Closed Circuit Television) and the second simulating the complex image processing made by an OCR (Optical Character Recognition) CCTV. The latter system preserves text justification whenever text is enlarged by the subject. 10 naive subjects were tested. Observers had to monocularly read one french sentence from a french newspaper per trial with a 10° artificial macular scotoma. Subjects could control text enhancement by using a response box. The three visual-aid conditions were alternated across blocks and reading speed was assessed over 8 one-hour sessions to investigate the effects of learning. At the end of the experiment, subjects were asked to give a comfort grade for each EVES.
Mixed effect analysis showed similar reading speed for our gaze-contingent visual aid and the OCR CCTV. These two systems had better reading speed compared to the standard CCTV (13%, p=0.01<0.05). These two systems had also similar comfort grades, that were higher than the standard CCTV (p<0.01).
The similarity between the gaze-contingent system and the ROC CCTV as well as their slight advantage over the standard CCTV is very encouraging. Future research should investigate whether these results can be generalized to other conditions (ex: different scotoma sizes, screen sizes…).
This PDF is available to Subscribers Only