MAIA microperimeter for central vision loss: Repeatability of short-duration fixation stability measurements

Abstract

Purpose : Fixation stability has become an important outcome measure for evaluating intervention and/or disease progression in patients with central vision loss. The most common instruments to assess fixation stability in these patients are the Nidek MP (1 and 3) and MAIA microperimeters. Repeatability of short-duration fixation stability has been reported for the MP-1, but not for MAIA. The purpose of this cross-sectional study was to examine the repeatability of fixation stability measured with MAIA microperimeter, for a fixed 20s-duration.

Methods : Fixation stability was evaluated in 32 eyes of 20 patients (8F/12M, mean age 76 ± 8 years) with macular diseases using MAIA and the MP-1 microperimeters, in a random order, twice for each eye and with each instrument. Fixation duration was 20s and all tests were performed in the same day. Based on visual acuity, 17 eyes were identified as the better eye (BE) and 15 as the worse eye (WE). Fixation stability was quantified with the 95% bivariate contour ellipse area (BCEA). The BCEA was recorded from the examination output as well as calculated from the raw data. A log transformation was applied to the BCEA values. Bland-Altman plots were used to determine the bias and the 95% limits of agreement.

Results : For MAIA, the bias and the 95% limits of agreement for the BE, the WE, and the overall sample were 0.1 (-0.56 to 0.76) log deg², 0.0 (-0.72 to 0.72) log deg², and 0.05 (-0.64 to 0.74) log deg², respectively. For the MP-1, these values were 0.06 (-0.46 to 0.58) log deg², 0.03 (-0.33 to 0.38) log deg², and 0.04 (-0.41 to 0.49) log deg². The expected number of raw data points recorded over a 20s interval was 500, but the actual numbers ranged from 241 to 496 for MAIA and from 486 to 512 for the MP-1. Far outliers in the raw data were included in the BCEA values reported in the output for MAIA, but not for the MP-1.

Conclusions : The 95% limits of agreement for 20s-fixation stability are larger for MAIA than for the MP-1. Unlike the MP-1, MAIA includes outliers in the BCEA calculation and, in some instances, fails to record all data points. Repeatability of fixation depends on the instrument used and this should be considered when interpreting changes in fixation stability in patients with central vision loss.

This is a 2021 ARVO Annual Meeting abstract.