A 44 channel suprachoroidal retinal prosthesis: interim functional vision results.

Abstract

Purpose : The 44 channel (44Ch) suprachoroidal retinal prosthesis is a second-generation bionic eye implant that follows on from a proof of concept study conducted between 2012 and 2014. The 44Ch implant is designed to provide artificial vision (phosphenes) to recipients with end stage retinitis pigmentosa (RP). We aimed to compare the performance of functional vision tasks, pre-implant and post activation of the device.

Methods : The 44Ch suprachoroidal retinal prosthesis was unilaterally implanted in four participants (one female) with advanced RP, age range 39 to 66 years, between February and August 2018. After a 16-week period of vision rehabilitation training, participants were assessed on six functional vision tasks: table-top search (TTS), doorway detection (DWD), obstacle avoidance (OA), moving bar (MB), square localisation (SL) and grating acuity (GA). Assessment time points were prior to implantation and from post device activation, weeks 17 (W17), 20 (W20), 32 (W32) and 44 (W44). Data was pooled across all 4 participants and performance compared between device on and off from W17.

Results : On average the device improved participants’ ability to verbally locate objects (%) on the TTS at W17 (p=0.004), W20 (p=0.003), W32 (p<0.001) and W44 (p=0.002) compared to device off. Device also improved participants ability to successfully detect and touch (%) the doorway on the DWD: W17 (p=0.002), W20 (p=0.044), W32 (p=0.003) and W44 (p=0.001). More obstacles were detected during OA with device on (%): W17 (p=0.005), W20 (p<0.001), W32 (p=0.020) and W44 (P=0.013) compared to device off. With device on three participants could discriminate MB speeds ranging from 7 to 30 degrees per second. Average pointing error across all visits on SL was 10.3 ± 3.3° (device on) versus 27.7 ± 8.7° (device off), p < 0.001. Two participants had measurable grating acuity of 0.033 cycles-per-degree.

Conclusions : The interim data for the 44Ch suprachoroidal implant demonstrates overall performances on function vision tasks are better with device on compared to device off. The device has the capability to improve functional vision for people with profound vision loss due to RP.

This is a 2020 ARVO Annual Meeting abstract.