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Etienne M Schonbach, Artur V Cideciyan, Mohamed A Ibrahim, Rupert Wolfgang Strauss, David G Birch, Janet S Sunness, Srinivas R. Sadda, Hendrik P Scholl; Static and dynamic assessment of fixation stability in Stargardt disease. Invest. Ophthalmol. Vis. Sci. 2018;59(9):788.
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© ARVO (1962-2015); The Authors (2016-present)
Sensitive, reproducible visual function biomarkers are necessary to evaluate the efficacy of emerging treatments for Stargardt disease type 1 (STDG1) in clinical trials. We previously demonstrated that fixation stability may serve as a secondary outcome parameter for visual function loss. However, the test duration and protocol have an unknown effect on the assessment of fixation stability. Here, we hypothesize that separate fixation testing with a single target is different from combined fixation testing using the same target with simultaneous perimetry testing.
Microperimetry data from the multicenter prospective Progression of Atrophy Secondary to Stargardt Disease (ProgStar, NCT01977846) study were used for the analysis. Patient selection criteria are defined in ProgStar Report No.1 (Ophthalmology 123: 817-28; doi: 10.1016/j.ophtha.2015.12.009). The MP-1 microperimeter (Nidek Technologies) was used to record all fixation events. During a separate fixation exam, the patient’s fixation stability (FS) was tested using a red cross as a target. During the macular sensitivity exam, the patient’s attention was also at the fixation target while the subject was simultaneously instructed to detect light stimuli projected in the visual field. The first 30s of the test duration were extracted for fixation data analysis.
The demographic features from the ProgStar cohort are detailed in ProgStar Report No.1. A total of 438 eyes from 235 patients were included. The mean 1SD-BCEA (Bivariate Contour Ellipse Area) was smaller for the cross fixation compared to the 30s sample extracted from the full macular sensitivity exam (4.9± 9.3 deg2 vs 5.48± 7.7 deg2; p<0.001). The 1SD-BCEA was also smaller for the 30s extracted versus the full macular sensitivity exam (5.48± 7.7 deg2 vs 12.6±16.2 deg2; p<0.001). The correlation of FS from the 30s with FS from the separate fixation test was weaker (ρ= 0.361, p<0.001, N= 391) compared to the correlation of the FS from the 30s with the FS from the full macular sensitivity test (ρ= 0.662, p<0.001; N= 404).
Our data suggest that differences in static and dynamic assessment of fixation stability are not only dependent on different test durations but also on the testing protocol of a single fixation target versus fixation target plus simultaneous perimetry testing.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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