Abstract
Purpose :
The main characteristics of smooth pursuit are well described, even for young people, but not many studies have analyzed performance in strabismic patients, and it is not clear whether there are differences between the different types of strabismus. In this study, we analyzed smooth pursuit eye movements of children with the diagnosis of intermittent exotropia or accommodative esotropia, compared with age-matched controls.
Methods :
Participants were 54 children, aged between 4 and 13 years old (21 cases of accommodative esotropia, 17 cases of intermittent exotropia and 16 controls). Eye movements were recorded using a Tobii Pro X3 eye tracker (120Hz) while performing different tasks. To produce smooth pursuit a single image was presented at the center of the screen, which jumped to a new position 14° to the right or to the left and immediately started to move horizontally across the screen with a sinusoidal movement, with a velocity of 11°/s. Smooth pursuit latency and gain, as well as the number of saccades during pursuit, were analyzed. Non-parametric Mann–Whitney U test was used to compare performance between each clinical group and controls and to determine the effect of age.
Results :
Smooth pursuit showed different characteristics in the three groups, although variability was very high. Gain was significantly lower in intermittent exotropia, compared to the control group (0.86 vs 0.92, Z=-3,549, p<0.001). In contrast, for smooth pursuit latency, patients with accommodative esotropia differed from controls (255 msec longer latencies; Z=-2.25, p=0.024). Accommodative esotropia patients also showed a significantly higher number of saccades during pursuit (mean difference: 3; Z=-2.69, p=0.007) of smaller amplitude (Z=-4,267, p<0.001) compared to controls. Main differences with the other two groups were also found in the number of anticipatory saccades. When change with time (age) of all variables was analyzed, each group progressed differently during development.
Conclusions :
These results indicate that smooth pursuit is affected by strabismus, but performance differs between clinical subtypes. More studies are needed to understand developmental effect and evaluate the influence on treatment outcomes.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.