gms | German Medical Science

Artificial Vision — The 2nd Bonn Dialogue. The International Symposium on Visual Prosthesis

Retina Implant Foundation

19.09.2009, Bonn

Mobility testing and its Repeatability in RP Patients with profound visual impairment: Learning effects, coping strategies and other influencing factors

Meeting Abstract

  • author Michaela Velikay-Parel - Department of Ophthalmology, Medical University Graz, Austria
  • D. Ivastinovic - Department of Ophthalmology, Medical University Graz, Austria
  • Th. Georgi - Department of Ophthalmology, Medical University Graz, Austria
  • R. Hornig - IMI Intelligent Medical Implant GmbH, Bonn, Germany
  • A. Langmann - Department of Ophthalmology, Medical University Graz, Austria

Artificial Vision – The 2nd Bonn Dialogue. The International Symposium on Visual Prosthesis. Bonn, 19.-19.09.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ri24

doi: 10.3205/09ri24, urn:nbn:de:0183-09ri242

Veröffentlicht: 30. November 2009

© 2009 Velikay-Parel et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen ( Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.



Purpose: We created a visual function test, the Graz mobility test (GMT) to document visual progress in artificial vision. In previous studies our visual function test adequately graded the low vision of patients with retinitis pigmentosa (RP). However in repeated testing the learning effect could contaminate the results after implantation. Therefore test and retests were performed in various time intervals on low vision RP patients.

The aim of this study was to investigate the consistency of the performance in patients in repeated testing and to study the learning effect for later use in artificial vision. Furthermore behavioral changes during retests were first time recorded and assessed.

Methods: 16 low vision RP-patients with a visual acuity from hand motion to 20/800voluntered. Repeated testing was performed in 1, 2, 3 and 6 months time intervals. The GM test consisted of four different, structurally similar mazes with 11 obstacles. The subjects passed through each course several times. A people tracking system with an integrated trajectory projection system was established to record horizontal and vertical scanning movements of people whilst walking through the test. Passage time, walking speed, number of contacts, frequency of scanning movements and average scanning angle were recorded.

Results: In repeated testing significant changes of the passage time were observed once the patients became familiar with the mobility test. The maximum learning effect was achieved within the first test session and was never exceeded in the following sessions. However further changes in the remaining parameters were observed in each patient, displaying behavioural changes correlating to the level of comfort during the task performance.

Conclusion: The GM proves to be reliable for repeated testing in low vision patients and the learning effect will not contaminate the results of visual function changes. Furthermore behavioural changes can be objectively assessed.

This lecture is available as video recording (Attachment 1 [Attach. 1]).