Test-Retest Reliability and Inter-Ocular Symmetry of Multi-Focal Electroretinography in Stargardt Disease

Abstract

Purpose: To evaluate test-retest reliability and inter-ocular symmetry of multi-focal electroretinography recordings in Stargardt disease and in patients without retinal pathology.

Methods: Multi-focal electroretinography were recorded with continuous fundus monitoring using the VERIS multifocal recording system using an array of 103 hexagons spanning 50° of central retina. Recordings were made sequentially from one eye (test-retest) followed by recordings from the fellow eye. A departure score, expressed as a percentage difference from the first recording (or from the fellow eye), was calculated for each comparison and parameter.

Results: Multi-focal electroretinography response topographies were similar within and between eyes for a particular individual and parameter. However, local response variability within and between eyes was significantly higher in Stargardt disease than in patients without retinal pathology for both amplitude and timing parameters. Amplitude variability in Stargardt disease decreased with more peripheral targets and with larger stimuli but never to the levels achieved with normal observers.

Conclusions: Both test-retest reliability and inter-ocular symmetry of multi-focal electroretinography responses were significantly lower in Stargardt disease compared to normal eyes, a finding attributable primarily to unsteady fixation. The greater variability between eyes in Stargardt disease may also reflect pathological differences in the topography of retinal function. This inherent variability must be taken into consideration if the multi-focal electroretinography is to be sufficiently sensitive to reliably detect small differences in retinal function.

KEYWORDS::

• Multi-focal electroretinogram
• Reliability
• Stargardt disease
• Visual function

ACKNOWLEDGMENTS

Declaration of interest: We are grateful to the Foundation Fighting Blindness and to the Sarkaria Family Fund for their generous support of this research. The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.