Month 18 changes in microperimetric mean sensitivity, fixation location, and fixation stability in
Stargardt disease: The ProgStar Study

Abstract

Purpose : Degeneration of photoreceptors and the retinal pigment epithelium in autosomal recessive Stargardt disease (type 1; STGD1) eventually leads to bilateral reduction of visual acuity and macular sensitivity. Affected patients begin to use an eccentric, less affected, location of the retina to fixate once the center of the macula is involved, often with considerably reduced stability of fixation. Here, we present the month 18 longitudinal changes of the microperimetric mean sensitivity (MS), fixation location, and fixation stability in the prospective, multicenter, longitudinal, observational ProgStar study (NCT01977846).

Methods : The MP-1 Microperimeter (Nidek Technologies) was used to measure MS of the central 20° 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 in patients with ABCA4-related STGD1. Data were graded for month 0, 6, 12, and 18. Linear mixed effects models were used to estimate the rate of change of MP parameters per year.

Results : At baseline, 238 patients (105 males, 44 %) with 444 eyes and a median age of 32 years (mean, 33.8 years; range, 7-69 years) were included in this analysis. Median MS at baseline was 12.1 dB (mean, 10.8 dB; range, 0- 19.9 dB). MS at month 18 was 10.9 dB (mean, 9.76 dB; range, 0-20.0 dB) and a yearly change of -0.69 dB (95 % CI, -0.83 to -0.55 dB) was calculated. The median BCEA at baseline was 21.4 deg² (mean, 30.8 deg²; range, 0.37-220.6 deg²) and 21.4 deg² at month 18 (mean, 31.1 deg²; range, 0.37- 266.9 deg²) with a non signficant yearly increase of 0.06 deg² (95 % CI, -1.7 to 1.8 deg²). The median PRL distance was 6 deg from the anatomical fovea (mean, 6.24 deg; range, 0 to 25 deg) at baseline and remained stable at month 18 (mean, 6.16 deg; range, 0 to 26 deg) with a yearly change of -0.10 deg (95 % CI, -0.27 to 0.07 deg). Both improvements and worsening of eccentricity and fixation stability were observed.

Conclusions : In our cohort of 238 cases of STGD1 with 18 months of follow-up, the annual rate of change in microperimetric measures was not statistically significant for fixation location or stability. Mean sensitivity showed a statistically significant annual decline of 0.69 dB.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Longitudinal follow-up of mean sensitivity in eyes with ABCA4- related Stargardt disease.