Six-month-change in microperimetric mean sensitivity, fixation location and fixation stability in Stargardt disease: The prospective ProgStar study

Abstract

Purpose : Better retinal sensitivity as well as central and stable fixation have been associated with better visual function in Stargardt disease (STGD1), but there is a paucity of data regarding the longitudinal changes of these findings. Here, we report 6-month data from a prospective, multicenter, longitudinal, observational study to describe the changes in microperimetric mean sensitivity (MS), fixation location and fixation stability in a large cohort of STGD1 patients.

Methods : Patients with ABCA4-related STGD1 underwent testing with the MP-1 Microperimeter (Nidek Technologies) which measured the MS of the central 10° of the macula, fixation stability through the 95.4 %-Bivariate Contour Ellipse Area (BCEA), and fixation location as the distance of the preferred retinal locus (PRL) from the anatomical fovea. Microperimetric testing was performed and images were graded at baseline and at month 6. Linear models with generalized estimating equations were used to analyze the change in MP-1 measures while accounting for between-eye correlations.

Results : A total of 238 patients (105 males, 44 %) and 403 eyes were enrolled. At baseline, median age was 32 years (mean, 33.8 years; range, 7- 69 years), median MS was 12.1 dB (mean, 10.8 dB; range, 0 dB-19.9 dB), median PRL eccentricity was 6° (mean, 6.2°; range, 0°- 25°) and the median BCEA was 21.4 deg² (mean, 31.1 deg²; range, 0.370 deg²- 267 deg²). At month 6, the mean loss of MS was 0.48 dB (95% CI -0.75 dB, -0.23 dB; p= 0.0003). The mean change of eccentricity of fixation location from the anatomical fovea was 0.066° (95% CI -0.27°, 0.40°; p=0.698) and the mean change of the BCEA was -0.47 deg² (95% CI -3.6 deg², 2.7 deg²; p=0.771); thus, both improvements and worsening of fixation location and stability were observed. Each degree of increased PRL eccentricity after 6 months was associated with an increase in BCEA of 2.97 deg² (95% CI 1.95 deg², 4.00 deg²; p<0.0001).

Conclusions : After a 6-month follow up, there was a statistically but not clinically significant loss in mean sensitivity (MS) of 0.48 dB. This was not associated with significant changes in fixation location and stability after 6 months.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.