gms | German Medical Science

Objective: Our aim is to present the clinical and multimodal imaging characteristics of two RP patients before and after Argus II retinal prosthesis implantation.

Materials and Methods: First patient was a 58 years-old male with end-stage RP. His vision was light perception bilaterally for 5 years. He was phakic with axial length of 23.13 mm. He received prosthesis implantation simultaneously with phacoemulsification and intraocular lens implantation. Second patient was a 36 years old male with only light perception bilaterally. He was pseudophakic with an axial length of 24.95 mm. The patients were evaluated before and after the prosthesis implantation by detailed ophthalmological examination, anterior and posterior segment photography and SD-optical coherence tomography (OCT). Fitting for identification of electrical stimulation threshold levels were done 2 weeks after the surgery. Rehabilitation sessions started after the first month. The follow-up period was 20 and 9 months respectively.

Results: During and after the implantation no adverse effect was encountered intraocularly or extraocularly. The system was actively used at least 2.5‒5 hours /day. The electrode arrays remained stable over the macula and in contact with the retina. In the first patient after 9 months there were a few cystic spaces seen in the retina under the array and some fibrous strands on the retina. This patient could identify black letters on white and write his name. He could recognize black figures on white, identify black numbers on white, sort the numbers, place the numbers of the clock hours and the hour hands correctly. Second patient who was very eager to use the system, especially had increased comfort during walking alone, avoiding obstacles outside home when the system was active. We could evaluate integrity and flow rate of the deep capillary plexus of the retina where the array was implanted and compared the findings with the fellow eye using OCT-Angiography (AngioVue, Optovue, Inc. Fremont, CA).

Discussion: Both of our patients showed a continuous vision-related improvement in the performance of several real-life tasks. The system was found to be effective in increasing self-confidence. And OCTA seemed to be a useful non-invasive imaging modality for evaluation of implanted retinal area before and after epiretinal prosthesis implantation.