gms | German Medical Science

Artificial Vision 2013

The International Symposium on Visual Prosthetics

08.11. - 09.11.2013, Aachen

Investigating assistive functions for visual prosthesis with low-vision patients

Meeting Abstract

  • Michael Scott Evans - Newcastle University, Institute of Neuroscience, Newcastle, UK; Newcastle University, School of EEE, Newcastle, UK
  • Q.C. Vuong - Newcastle University, Institute of Neuroscience, Newcastle, UK
  • P. Degenaar - Newcastle University, School of EEE, Newcastle, UK
  • R. Cheong-Leen - Imperial College, Department of Medicine, London, UK
  • S. George - Imperial College Healthcare NHS Trust, Western Eye Hospital, London, UK

Artificial Vision 2013. Aachen, 08.-09.11.2013. Düsseldorf: German Medical Science GMS Publishing House; 2014. Doc13artvis30

doi: 10.3205/13artvis30, urn:nbn:de:0183-13artvis307

Published: February 13, 2014

© 2014 Evans et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Visual prostheses have returned poor visual acuity. This is akin to patients with macular degeneration (AMD). We therefore use this cohort to study visual assistive functions for visual prosthesis. Here we investigated whether an auditory feedback system could facilitate face identification.

Materials and Methods: Sixteen AMD patients were recruited from Western Eye Hospital, London. The patients were tested with a face discrimination task, in which they reported whether two sequentially presented faces were the same or different. We measured how accurately and quickly they responded on each trial. In one block, we provided auditory feedback on whether the faces matched or not and in another block, there was no auditory feedback. The faces were blurred and contrast-reduced to different levels in order to simulate different viewing distances and lighting conditions.

Results: We found that patients’ accuracy was systematically affected by blurring and contrast reduction but not by auditory feedback. Patients, however, responded more quickly on feedback blocks.

Conclusion: An auditory assistive function can facilitate face identification, possibly by providing an alerting signal, without adversely affecting accuracy. Our study further suggests that visual prostheses which incorporate face-recognition technology also need tuning according to user requirements. The ultimate purpose of our studies is to provide these parameters (e.g., at what viewing distance would the users begin to rely on assistive functions or at what accuracy level would the users tolerate assistive functions).

Acknowledgement: This work was funded by the BRC and Newcastle EEE.