Abstract
Purpose: :
Abnormalities in saccades appear to be sensitive and specific biomarkers in the pre-diagnostic stages of Huntington disease (HD) The goal of this study was to evaluate test-retest reliability of saccadic measures in prediagnostic carriers of the HD gene expansion (PDHD) and normal controls (NC).
Methods: :
The study sample included 12 NC and 9 PDHD who completed two study visits within an approximately one month interval. At the first visit, all participants completed a uniform clinical evaluation. A high resolution video-based system was used for recording eye movements during completion of the battery of visually guided, anti-saccade, and three memory guided tasks. Measures of the saccades (latency, velocity, gain, and percentage of error saccades) were quantified. Test-retest reliability was evaluated by calculating the intraclass correlation (ICC) of the saccade measures collected at the first and second visits. Additionally, regression analysis was used to evaluate the influence of age, gender, and group (NC or PDHD) on difference in measures between visits.
Results: :
Percentage of error saccades showed good test-retest reliability in anti-saccade and memory guided tasks (average ICC=0.8, p<0.001). The latency of saccades also demonstrated good test-retest reliability (averaged ICC=0.74, p< 0.02) across all tasks. The velocity and gain of saccades showed moderate reliability (ICC~0.5). ICC was similar in NC and PDHD groups for most measures. There were no significant group, age, or gender effects when analyzing the difference in each saccade measure between the first and second visit.
Conclusions: :
Good test-retest reliability of saccadic latency and percentage of errors in anti-saccade and memory guided tasks suggests that these measures could serve as potential biomarkers to evaluate progression in HD.
Keywords: eye movements: saccades and pursuits • ocular motor control