Development of a Mountable Filtering System for Enhancing Visual Perception of the Argus II Retinal Prosthesis

Abstract

Purpose : The ability to interpret the artificial visual stimulus created by the Argus II retinal prosthesis can vary with the user’s perceptual capabilities and the scene captured by the device’s camera. Outcomes and proficient use may be improved through the introduction of filters as a rehabilitation tool. A mountable filtering system was developed allowing the user to transform the visual stimulus captured by the camera. This study investigates the feasibility of incorporating a filter as a tool to improve scene and pattern recognition.

Methods : Using CAD software and 3D printer, filter holders and an eyewear mount were developed (Fig. 1). During inpatient rehabilitation sessions, Eschenbach tints (17, 21, 31) were held over the user’s camera to determine if visualization was improved. Gel film filters with comparable transmission characteristics (green 45%, plum 19%, grey 25%, clear control 99%) were mounted on holders with tactile marks for ease of identification. Each mount can hold up to 2 filters permitting the user to explore and combine filters. The filter system was deployed remotely to one Argus II user with the usage instructions and testing protocol. Filter comparisons were completed both indoors (lit/darkened room) and outdoors (sunny/overcast). The indoor scene consisted of observing a PC screen with a single white line in various orientations. The outdoor scene consisted of visualizing colored 2.5-inch balls with either grass or asphalt background. Filters were graded on a scale: -2 to +2 with zero indicating no change and the -/+ scores indicating decreases or increases in perception. The user was naïve that one filter was a control (Fig. 2).

Results : Indoor visualizations of the computer screen targets in a darkened room were improved with positive ratings, compared to no filter and the control. Conversely, indoor filter usage with incandescent illumination was rated negatively, compared to no filter. Outdoor usage of filters when identifying targets on various backgrounds did not improve visualization.

Conclusions : A mountable filtering system can be deployed to remote Argus II users, with preliminary data indicating indoor visualization improvements, as a function of room illumination. Additional user testing is required to understand the effects of the spectral characteristics of each filter.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

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