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

Abstract

Purpose:

To describe two methods of measuring Argus II array–retina distance and to correlate array–retina distance to electrode stimulation thresholds.

Methods:

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.

Results:

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.

Conclusion:

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.