Retinal Anatomy and Electrode Array Position in Retinitis Pigmentosa Patients After Argus II Implantation: An International Study

PURPOSE: To assess the retinal anatomy and array position in the Argus II Retinal Prosthesis recipients. DESIGN: Prospective, non-comparative cohort study METHODS: Setting: international multicenter study Patients: Argus II recipients enrolled in the Post-Market Surveillance Studies. Procedures: Spectral-domain Optical Coherence Tomography images collected for the Surveillance Studies (NCT01860092 and NCT01490827) were reviewed. Baseline and postoperative macular thickness, electrode-retina distance (gap), optic disc-array overlap, and preretinal membrane presence were recorded at 1, 3, 6, and 12 months. Main Outcome Measures: Axial retinal thickness and axial gap along the array’s long axis (a line between the tack and handle), maximal retinal thickness and maximal gap along a B-scan near the tack, midline, and handle. RESULTS: Thirty-three patients from 16 surgical sites in the United States and Germany were included. Mean axial retinal thickness increased from month 1 through month 12 at each location, but reached statistical significance only at the array midline (p- value=0.007). The rate of maximal thickness increase was highest near the array midline (slope=6.02, p=0.004), compared to the tack (slope=3.60, p