Abstract
Purpose :
Research on infantile nystagmus syndrome (INS) and velocity discrimination is limited, and no research has examined velocity discrimination in subjects with INS at their null position and away from it. This study aims to investigate how individuals with INS perform, compared with controls, when carrying out velocity discrimination tasks. Particularly, the study aims to assess how the null position affects their performance.
Methods :
INS subjects (N=21) and controls (N=16) aged 12 and above were recruited. They were required to perform horizontal and vertical velocity discrimination tasks at two gaze positions. For INS subjects, testing was done at the null position and 15° away from the null. If there was no null, testing was done at primary gaze position (straight-ahead) and 15° away from primary. For controls, testing was done at primary gaze position (straight-ahead) and 20° away from primary. Horizontal and vertical velocity discrimination thresholds were determined by a Weber fraction (ΔV/V). Two-way ANOVAs were used for statistical analysis.
Results :
INS subjects showed significantly higher horizontal (37.59±18.56%) and vertical (28.12±12.40%) velocity discrimination thresholds compared with controls (horizontal: 19.85±10.06%, vertical: 19.75±9.39%) at both gaze positions (P<0.001). Within the INS group, 12 INS subjects who had an identified null position showed significantly lower horizontal (27.00±7.90%) and vertical (23.08±8.58%) thresholds at the null than at 15° away from it (horizontal: 37.61±18.08%, vertical: 28.89±9.23%, P<0.05).
Conclusions :
Velocity discrimination was impaired in INS subjects, with better performance at the null. These findings could assist us in understanding of how INS actually affects the daily activities of patients, and aid us in developing new clinical visual function assessment for INS.
This is a 2021 ARVO Annual Meeting abstract.