Correlation between Argus II array-retina distance and electrical thresholds of stimulation is improved by measuring the entire array.

Abstract

To describe two methods of measuring Argus II array-retina distance and to correlate array-retina distance to electrode stimulation thresholds. This was a case series of eight patients implanted with the Argus II. Spectral domain-optical coherence tomography array-retina distance was measured by two methods and correlated to corresponding electrode thresholds: (1) array-retina distance at each array corner and the largest array-retina distance and (2) using manual optical coherence tomography segmentation, the average array-retina distance was determined for each group of four electrodes. Patients 1-5 and 6-8 were analyzed separately due to a different threshold programming software. The Spearman's rank coefficient between array-retina distance and thresholds was -0.006 (p = 0.98) for patients 1-5, and 0.16 (p = 0.59) for patients 6-8 with the first method. The Spearman's rank coefficient was 0.25 (p < 0.001) for patients 1-5 and 0.36 (p < 0.001) for patients 6-8 with the second method. There is a positive correlation between array-retina distance and threshold measurements when measuring the entire array but not when using a faster measurement method of four corners and largest array-retina distance.