A novel dynamic random-dot stereopsis assessment to measure stereopsis in intermittent exotropia

To investigate dynamic stereopsis in intermittent exotropia [X(T)] patients using a novel dynamic random-dot stereopsis assessment method.

A novel dynamic random-dot stereopsis test was performed using novel self-programmed software, which consisted of red and green dots and four blocks on the screen. The test included motion + disparity (MD), motion (M), and disparity (D), where the D cues ranged from 200 to 1,200 arc-seconds. The characteristics of preoperative dynamic stereopsis in 83 X(T) patients and associations with clinical features were analysed, and the prognosis was followed up on the 1^st day and at the 2^nd, 6^th and 12^th months postoperatively.

Preoperatively, the mean reciprocal values of near and far stereopsis were 0.013±0.0016 and 0.0011±0.0005 arc-seconds in static stereopsis patients, respectively, and the MD, M, and D values were 0.002±0.0002, 0.0018±0.0001, and 0.0012±0.0002 arc-seconds in dynamic stereopsis, respectively. The MD value was negatively correlated with the Newcastle control score, disease course, and prism deviations (P<0.05), M was correlated with disease course and the Newcastle control score (P<0.05), and D was not correlated with any clinical features. Postoperative dynamic stereopsis improved from the 1^st day and gradually peaked at the 6^th month, while static stereopsis showed a decreased tendency in near but not far stereopsis.

The dynamic stereopsis quantitative evaluation method based on random dots is a feasible test and shows that destruction of X(T) patients' dynamic stereopsis is affected by age at surgery, disease course, strabismus controllability and the strabismus degree.