Cross-sectional evaluation of microperimetric fixation location and stability in Stargardt disease in the ProgStar study

Abstract

Purpose : To investigate the relationship between microperimetric fixation location (FL) and fixation stability (FS), demographic features, and best-corrected visual acuity (BCVA) in Stargardt disease (STGD1) as part of the multicenter ProgStar study (The Natural History of the Progression of Atrophy Secondary to Stargardt Disease).

Methods : We enrolled patients with ABCA4-related STGD1 in a multicenter, prospective, cross-sectional, observational study. We used MP1 data (Nidek Technologies): FL was expressed as the eccentricity of the preferred retinal locus (PRL) from the anatomical fovea, FS as the 95.4 %-bivariate contour ellipse area (BCEA), and best- corrected visual acuity (BCVA) as ETDRS letters. Linear models with generalized estimating equations were used for statistical analysis while accounting for between-eye correlations.

Results : Of 238 patients, 105 (44 %) were males. Median age was 32 years (mean, 33.8 years; range, 7- 69 years) and the median duration of symptoms was 9 years (mean, 11.8 years; range, 0- 55 years). Median PRL eccentricity from the fovea was 6° (mean, 6.2°; range, 0°- 25°), median BCEA was 21.4 deg² (mean, 31.1 deg²; range, 0.370 deg²- 267 deg²), median BCVA was 42 ETDRS letters (mean, 46.2 letters; range, 20- 88 letters). Each year of additional disease duration was associated with 0.11° more eccentric FL (p =0.0008) but not with FS (p =0.936). Each year of later onset of symptoms of STGD1 was associated with 0.14° more central FL (p < 0.0001) and 0.84 deg² smaller BCEA (p <0.0001). Each year of additional age was associated with 0.67° more central fixation (p =0.0007) and 0.46 deg² smaller BCEA (p =0.0014). A single linear model best described the relationship between FL and BCVA: one degree farther PRL eccentricity was associated with 2.3 letters loss of BCVA (p <0.0001) and one additional letter of BCVA with 0.15° more central FL (p <0.0001). The association of FL with BCVA was robust after adjusting for BCEA. Pearson correlation coefficients between patients’ right and left eyes were 0.892 (p <0.0001) for FL and 0.851 (p <0.0001) for FS. After 10 years of disease duration, 82 % of patients had more than 2° PRL eccentricity in both eyes.

Conclusions : Longer disease duration is associated with an increase of eccentricity and loss of stability of fixation in STGD1.

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