gms | German Medical Science

Purpose: Retinal prostheses have restored partial vision in blind patients with advanced retinitis pigmentosa. However, the visual field provided by these devices is very narrow, limiting patients' ability to perform daily activities. We are developing a next-generation retinal prosthesis that aims to expand the visual field to cover a wider area of the retina. Additionally, we have created a new retinal prosthesis simulator to test the visual capabilities of this next-generation device.

In this study, we investigated the effect of visual field size on visual recognition using the retinal prosthesis simulator in healthy subjects.

Materials and Methods: Eleven participants with normal vision used the retinal prosthesis simulator. Images captured by a webcam attached to a head-mounted display (HMD) were processed by a computer and displayed on the HMD. Participants performed three tasks: (1) recognizing shapes (circle, square, triangle) on a black background, (2) identifying a randomly selected alphabet letter, and (3) recognizing one of five randomly selected objects (smartphone, PC mouse, cup, box, glasses case). Four visual field sizes (corresponding to 149, 60, 21, and 7 modules) were tested. Accuracy rates and response times were compared across the different conditions.

Results: In the shape recognition task, the average accuracy rate was nearly 100% across all groups, with no significant differences. However, the average response time was significantly longer for the 7-module group (P<0.0001). In the alphabet recognition task, the accuracy rate for the 7-module group dropped significantly to 77.2% (P=0.0004), and the response time increased to 5.3 seconds (P<0.0001). In the object recognition task, accuracy rates were similar across all groups, but the response time was significantly longer in the 7-module group (P<0.0001).

Conclusions: The study demonstrated that a visual field size corresponding to more than 21 modules (approximately 31x47 degrees) is