Analysis of Improvement Time and Influencing Factors of Diplopia after Intermittent Exotropia in Children

OBJECTIVE: To observe and analyze the occurrence rate, improvement time, and influencing factors of diplopia after intermittent exotropia in children. METHODS: A total of 135 children with intermittent exotropia treated in our hospital from February 2019 to April 2021 were recruited. A reasonable surgical plan was exerted according to the preoperative examination of the children, the children were divided into groups according to their age, degree of strabismus, visual acuity, and binocular visual function, and the postoperative diplopia occurrence rate and improvement time of diplopia in different groups were observed and compared. RESULTS: Postoperative diplopia occurred in 74 of 135 children with intermittent exotropia, and the postoperative incidence of diplopia was 54.81%. All diplopia occurred on the first day after the operation. There were 62 cases of contradictory diplopia (83.78%) and 12 cases of fusion of powerless diplopia (16.22%). Except for 1 case of amalgamated powerless diplopia, diplopia was not significantly improved after 6 months, which seriously affected the life of the children after the second operation, and all the others were significantly improved within 90 days. The improvement time of diplopia was 3–90 days, and the average improvement time of diplopia was 13.25 ± 3.16 days. According to their age, the children were divided into the 3–6 years old group (n = 69), the 7–10 years old group (n = 47), and the 11–14 years old group (n = 19). Postoperative diplopia occurred in 25 cases (36.23%) in the 3–6 years old group, 34 cases (72.34%) in the 7–10 years old group, and 16 cases (84.21%) in the 11–14 years old group. There was a significant difference in the incidence of postoperative diplopia among the three groups (P < 0.05). There was a significant difference in the improvement time of diplopia among the three groups (P < 0.05). According to the degree of strabismus before the operation, the children were divided into the <50△ group (n = 74) and the ≥50△ group (n = 61). Postoperative diplopia occurred in 32 cases (43.24%) in the <50△ group and 43 cases (70.49%) in the ≥50△ group. There was a significant difference in the incidence of postoperative diplopia between the two groups (P < 0.05). There was a significant difference in the improvement time of diplopia among the three groups (P < 0.05). According to the results of the visual acuity examination, the patients were divided into the ≥0.8 (naked eye) group (n = 21), the ≥0.8 (ametropia) group (n = 32), and the <0.8 (amblyopia) group (n = 32). Among them, diplopia occurred in 10 cases (47.62%) in the ≥0.8 (naked eye) group, 40 cases (48.78%) in the ≥0.8 (ametropia) group, and 24 cases (75.00%) in the <0.8 (amblyopia) group. The incidence of diplopia in the <0.8 (amblyopia) group was significantly higher than that in the ≥0.8 (naked eye) group and the ≥0.8 (ametropia) group, and the difference was statistically significant (P < 0.05). The postoperative diplopia improvement time in the <0.8 (amblyopia) group was significantly higher than that in the ≥0.8 (naked eye) group and the ≥0.8 (ametropia) group, and the difference was statistically significant (P < 0.05). There was no significant difference in diplopia occurrence rate and diplopia improvement time between the ≥0.8 (naked eye) group and the ≥0.8 (ametropia) group (P > 0.05). According to the results of binocular visual function examination, 92 cases had a primary function, 45 cases (48.91%) had diplopia after the operation, the average recovery time of diplopia was 12.58 ± 3.16, 43 cases had no primary function, and 30 cases (69.77%) had diplopia after the operation. The average recovery time of diplopia was 13.02 ± 3.84. There was a significant difference in the incidence of diplopia between the two groups (χ(2) = 5.162). There was no significant difference in the recovery time of diplopia between the two groups (χ(2) = 0.570, P < 0.05). In 80 cases with secondary function, diplopia occurred in 36 cases (45.00%), and the average recovery time of diplopia was 10.14 ± 2.88; in 55 cases without secondary function, diplopia occurred in 39 cases (70.91%), and the average recovery time of diplopia was 14.86 ± 3.73. There was a significant difference in the incidence of diplopia between the two groups (χ(2) = 8.861, P < 0.002). There was a significant difference in the recovery time of diplopia between the two groups (χ(2) = 6.469, P < 0.001). In 77 cases with tertiary function, diplopia occurred in 32 cases (41.56%), and the average recovery time of diplopia was 9.61 ± 2.39; in 58 cases without tertiary function, diplopia occurred in 43 cases (74.14%), and the average recovery time of diplopia was 13.11 ± 3.05. There was a significant difference in the incidence of diplopia between the two groups (χ(2) = 14.221 P < 0.001). There was a significant difference in the recovery time of diplopia between the two groups (χ(2) = 5.355, P < 0.001). CONCLUSIONS: The age, degree of strabismus, visual acuity, and binocular visual function of children with intermittent exotropia are significant factors affecting the occurrence rate and recovery time of diplopia after the operation. The younger the age, the smaller the degree of strabismus, the better the vision and the second or third grade of visual function, the smaller the occurrence rate of diplopia, and the shorter the recovery time of diplopia. Thus, the above influencing factors have a certain guiding significance in predicting the improvement of postoperative diplopia and the time of diplopia disappearance. The purpose of intermittent exotropia surgery in children is not only to correct eye position and improve appearance but also to establish normal retinal correspondence in order to obtain binocular monocular function. Furthermore, postoperative diplopia in children with concomitant exotropia is very common; therefore, careful examination, comprehensive analysis, and surgical plan should be designed according to the above factors. Stereoscopic vision training as early as possible after the operation is beneficial to the establishment of normal retinal correspondence and the elimination of diplopia.