Purchase this article with an account.
X.-Y. Chai, J. Fan, L. Zhang, Q. Ren; Accuracy and Disparity of Simulated Phosphenes Localization Using Digital Tactile Board. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1775.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
It is crucial to map phosphenes in an accurate way to exam and train the blind after visual prosthesis implantation. In this study, we investigate the accuracy and disparity of 3D phosphene positioning based on simulated vision using a digial tactile board (DTB).
The system is consisted of a 5DT head-mounted display, a self-developed experimental software system and a self-designed digital tactile board. The head mounted display (HMD) is used to simulate the phosphenes. The digital tactile board is used to position the distance and angle of phosphenes. Twenty volunteers from 24 to 30 years old are recruited in the study. Training is performed before the actual trial in order to make the subjects familiar with the experimental procedure. The subjects are asked to point out the phosphenes on the tactile board using their fingers. The distance and the vision angle both can be exactly expressed by the DTB. The time between the appearance of simulated phosphene and the identified position recorded by the DTB recorded by a timer. The effects of distance, quadrant and the long-term training are studied. The accuracy and disparity of phosphene locationlization are investigated using the digital tactile board.
The standard deviation (SD) of the judged points on various distances were less than 6mm. All of the values were at the range of 4-6mm. The range of mean error of the accuracy of judged points on various distances was 4-9mm. The response time on the distance of 56mm, 79mm, 113mm and 136mm was from 24.5 to 28.3 seconds, while the response time on 11mm distance was 17.7 seconds. The mean errors in four quadrants were reduced into the range from more than 10mm to less than 12mm. The long-term effect was evaluated by the accuracy and the disparity as well. The SD decreased with the number of the experiments increased during the five experiments, from more than 4mm to 3mm. As for accuracy, the mean error decreased from the second experiment and became stable in the last four trials and the stable values were from 5.7-6.1mm.
The accuracy and disparity to localize the simulated phosphenes were significantly improved using digital tactile board. The accuracy decreased as the distance to the origin increased, while the response time is greatly increased with the increase of the distances to the origin. Using digital tactile board could also increase the accuracy in four quadrants as well as reduce the geographic error among four quadrants. And long-term training experiment could improve both accuracy and disparity.
This PDF is available to Subscribers Only