[Comparison of clinical characteristics in intermittent exotropia patients with different visual perception and oculomotor control]

Objective: To explore the clinical characteristics of intermittent exotropia (IXT) patients with different visual perception and oculomotor control. Methods: A cross-sectional study was conducted. Minor IXT patients between March 2021 and May 2023 at Beijing Tongren Hospital were enrolled. Demographic characteristics were recorded, and visual perception and oculomotor control were evaluated. The patients were divided into simultaneous vision disappearing and existing groups, fusion disappearing and existing groups, distant stereoscopic vision disappearing and normal groups, and near stereoscopic vision injury and normal groups. Statistical description was performed by using M (Q₁, Q₃). Rank sum test was used to compare the Revised Newcastle Control Score (RNCS), near and far strabismus degree, duration of disease, and age of onset among different groups. The correlation between visual perception and oculomotor control and the correlation of duration of disease and age of onset with visual perception and oculomotor control were analyzed by Pearson correlation analysis. Results: A total of 381 patients were enrolled, including 189 males and 192 females, with a median age of 7 (6, 9) years. The incidence of normal visual perception was 19.4% (74/381). Compared with simultaneous vision and fusion existing groups and distant and near stereoscopic vision normal groups, the RNCS [7 (5, 9) vs 4 (3, 6), 6 (5, 8) vs 4 (3, 6), 5 (4, 7) vs 3 (3, 5), and 5 (3, 6) vs 4 (3, 6)], near strabismus degree [65^Δ (60^Δ, 80^Δ) vs 40^Δ (30^Δ, 50^Δ), 60^Δ (45^Δ, 65^Δ) vs 40^Δ (30^Δ, 50^Δ), 50^Δ (40^Δ, 60^Δ) vs 35^Δ (30^Δ, 45^Δ), and 45^Δ (30^Δ, 60^Δ) vs 40^Δ (30^Δ, 50^Δ)] and far strabismus degree [60^Δ (50^Δ, 75^Δ) vs 35^Δ (25^Δ, 50^Δ), 55^Δ (41^Δ, 65^Δ) vs 35^Δ (25^Δ, 45^Δ), 45^Δ (30^Δ, 60^Δ) vs 35^Δ (25^Δ, 45^Δ), and 40^Δ (30^Δ, 60^Δ) vs 35^Δ (25^Δ, 45^Δ)] increased significantly in disappearing simultaneous vision, fusion, and distant stereoscopic vision groups and injury near stereoscopic vision group (all P<0.05). Compared with simultaneous vision and fusion existing groups and distant stereoscopic vision normal group, duration of disease was significant longer in disappearing simultaneous vision, fusion, and distant stereoscopic vision groups [3 (1, 5) years vs 2 (1, 3) years, 2 (1, 4) years vs 1 (1, 3) years, 2 (1, 4) years vs 1 (1, 3) years, all P<0.05]. The age of onset in disappearing distant stereoscopic vision group was significantly lower than normal distant stereoscopic vision group [5 (3, 7) years vs 6 (4, 8) years, P=0.005]. Pearson correlation analysis showed that subjective angle and random dot stereogram (RDS) stereoacuity were positive correlation with RNCS, and the near and far strabismus degree (r=0.414, 0.516, and 0.559, all P<0.001; r=0.153, 0.142, and 0.173, all P<0.05). Subjective angle, RNCS, and the near and far strabismus degree were positive correlation with duration of disease (r=0.238, 0.195, 0.236, 0.239, all P<0.001) and negative correlation with age of onset (r=-0.184, -0.279, -0.112, -0.147, all P<0.05). Conclusions: Nearly 20% of IXT patients have normal visual perception. With the longer duration of disease or lower age of onset, the incidence of abnormal visual perception is higher and injury of visual perception and oculomotor control is more serious.