Benchmarking test-retest variability in microperimetry for intermediate age-related macular degeneration using MP-3 and MAIA.

Objective: Microperimetry (MP) has emerged as a clinical functional endpoint in nonexudative age-related macular degeneration (AMD). In this study, we aim to provide reference values for test-retest outcomes on two MP devices in intermediate AMD (iAMD).

Design: Prospective, cross-sectional study.

Participants: 3 600 stimuli from 20 eyes in 20 subjects.

Methods: Patients diagnosed with iAMD underwent consecutive testing on MP-3 (NIKED, Gamagori, Japan) and MAIA (CenterVue Icare, Padova, Italy). The obtained point-wise sensitivity (PWS) measurements were superimposed with optical coherence tomography (OCT) (Spectralis, Heildelberg Engineering) acquired. Hyperreflective foci (HRF), drusen volume, ellipsoid zone (EZ)-thickness and outer nuclear layer (ONL)-thickness were quantified with deep-learning algorithms. Subretinal drusenoid deposits (SDD) were manually annotated. We assessed test-retest repeatability at the location of these biomarkers using Bland-Altmann coefficients of repeatability. Furthermore, interdevice correlation, fixation stabilities, and examination durations were evaluated.

Results: Comparable overall point-wise retest variances were detected for MP-3 (±4.54 dB) and MAIA (±5.24 dB). SDDs led to significantly worse repeatability in the MAIA device (p = 0.03). Drusen, HRF, EZ-thickness, and ONL thickness had no significant impact on test-retest variance. A good intradevice correlation (MP-3: 0.869 [0.851 - 0.886] MAIA 0.848 [0.827 - 0.867]), and a good mean interdevice correlation (0.841 [0.819 - 0.861]) was observed.

Conclusions: Intradevice and interdevice repeatability for MP examinations with MP-3 and MAIA in patients with iAMD can be considered as good. Biomarkers except for SDD show no significant impact in repeatability in both devices. This supports MP as a reliable functional endpoint in clinical trials in iAMD.