Role of fusional convergence amplitude in postoperative phoria maintenance in children with intermittent exotropia

Wakayama, Akatsuki; Seki, Yukari; Takahashi, Rika; Umebara, Ikumi; Tanabe, Fumi; Abe, Kosuke; Matsumoto, Fumiko; Shimomura, Yoshikazu

doi:10.1007/s10384-018-0585-6

“…Scholars performed two methods and reported that the stereopsis of patients with intermittent exotropia after operation increased [22]. Li Dan et al have surveyed different types of intermittent exotropia and indicated that surgery is helpful to the recovery of binocular regulatory set function [23].…”

Section: Discussionmentioning

confidence: 99%

“…Scholars performed two methods and reported that the stereopsis of patients with intermittent exotropia after operation increased [ 22 ]. Li Dan et al have surveyed different types of intermittent exotropia and indicated that surgery is helpful to the recovery of binocular regulatory set function [ 23 ]. The clinical study of binocular visual function in children with intermittent exotropia before and after operation suggests that surgical therapeutics is beneficial to the reconstruction of binocular visual function [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

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

Wang

¹

,

Hong-ping

²

,

Zhang

³

et al. 2022

Journal of Healthcare Engineering

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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 (χ2 = 5.162). There was no significant difference in the recovery time of diplopia between the two groups (χ2 = 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 (χ2 = 8.861, P < 0.002 ). There was a significant difference in the recovery time of diplopia between the two groups (χ2 = 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 (χ2 = 14.221 P < 0.001 ). There was a significant difference in the recovery time of diplopia between the two groups (χ2 = 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.

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“…The fusional vergence amplitude reflects a patient’s ability to “control” a latent or intermittent deviation in IXT ( von Noorden and Campos, 2002 ; Adams et al, 2008 ) or a patient’s ability to maintain phoria in childhood X(T) ( Wakayama et al, 2018 ). Kushner and Morton (1998) and Kushner (1999) found that exotropia becomes more pronounced when fusional convergence is suspended.…”

Section: Discussionmentioning

confidence: 99%

“…Our study has limitations. First, the control score plays a vital role in assessing the patients’ ability to maintain phoria ( Hatt and Gnanaraj, 2013 ; Wakayama et al, 2018 ). However, it is unsuitable for patients with IXT after surgery.…”

Section: Discussionmentioning

confidence: 99%

Longitudinal Rehabilitation of Binocular Function in Adolescent Intermittent Exotropia After Successful Corrective Surgery

Peng

¹

,

Xu

²

,

Zheng

³

et al. 2021

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PurposeTo study the longitudinal rehabilitation of binocular visual function in adolescent intermittent exotropia (IXT) after successful surgery and compare the results with those of a normal population. The role of binocular function in ocular alignment stability was also evaluated postoperatively.MethodsIn this prospective study, 30 adolescents with IXT successfully corrected after 1 month were followed for 12 months, and 30 children with normal vision were enrolled as controls. Stereopsis, the fusional vergence amplitude, sensory fusion, and accommodative flexibility were measured to assess binocular function at baseline and 6 and 12 months postoperatively. The controls were tested once when they were enrolled in the study.ResultsThe deviation was −32.00 ± 8.60 prism diopters (PD) at distance fixation and −36.0 ± 9.10 PD at near fixation preoperatively with an average correction of 28.53 ± 3.79 PD and 30.67 ± 1.34 PD at 1 month postoperatively. Distance stereoacuity and near stereoacuity improved from 1 to 12 months postoperatively (p = 0.025 and p = 0.041, respectively). Compared with the controls, the fusional convergence reserve at distance (p = 0.025) and near (p = 0.033) fixations and fusion reserve ratio at distance (p = 0.000) and near (p = 0.000) fixations remained subnormal, whereas sensory fusion (p = 0.237), distance stereopsis (p = 0.120), and the fusional divergence amplitude at a distance (p = 0.168) were normal. However, no significant correlations were found between binocular functions at 1 month postoperatively and the postoperative drift.ConclusionBinocular function significantly improved from before to after successful corrective surgery and continued to improve from 1 to 12 months postoperatively in adolescents with IXT. No significant correlations were found between binocular functions at 1 month postoperatively and ocular alignment stability.

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“…Given their differences from normal children, binocular vision is more critical for children with IXT, as if these individuals lose maintenance of fusion, they could manifest exotropia. Previous studies proved that the positive fusional vergence (PFV) and fusion reserve ratio were correlated with the ability to maintain ocular alignment [13][14][15], and PFV was lower in IXT than in visually normal children [16,17], which could make it difficult for the fusional maintenance system to control ocular deviation. Since contact lenses for myopia control may influence the vergence and fusion systems in normal myopic children [8][9][10], therefore, it is worth exploring whether specialized spectacle lenses for myopia control will also affect binocular vision in myopic children, especially those with IXT.…”

Section: Introductionmentioning

confidence: 99%

Effect of Spectacle Lenses with Highly Aspherical Lenslets on Binocular Vision and Accommodation in Myopic Children with and without Intermittent Exotropia

Zhou

¹

,

Li

²

,

Huang

³

et al. 2022

Journal of Ophthalmology

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Purpose. To evaluate the influence of spectacle lenses with highly aspherical lenslets (HAL) on binocular vision and accommodation in myopic children with intermittent exotropia (IXT) and compare the changes after wearing HAL in binocular vision and accommodation in myopic children with or without IXT. Method. Forty myopic subjects aged 8–12 years were recruited: 20 with IXT and 20 visually normal children. Stereoacuity, phoria, accommodative facility, fusional vergence, vergence facility, near point of convergence, amplitude of accommodation, and accommodative response (AR) were measured by wearing HAL or single vision spectacle lenses (SVL) in a random order after adapting for 20 minutes. Accommodative microfluctuation (AMF) was defined as the standard deviation of AR. Changes in binocular vision and accommodation after wearing HAL were compared between the two groups. Results. No significant differences were found in binocular vision after wearing HAL versus SVL in either group (all P > 0.05 ). A greater AMF was found after wearing HAL than after wearing SVL in both groups (0.04 D, 95% confidence interval (CI), 0.03 to 0.05 D, P < 0.001 for the IXT group; 0.05 D, 95% CI, 0.03 to 0.07 D, P < 0.001 for the visually normal group); however, the other accommodation parameters did not change significantly (all P > 0.05 ). There were no differences in the changes after wearing HAL in any parameter between the two groups (all P > 0.05 ). Conclusion. HAL did not significantly change the binocular vision and accommodation for myopic children with or without IXT except for AMF in the short term.

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Role of fusional convergence amplitude in postoperative phoria maintenance in children with intermittent exotropia

Abstract: In childhood X(T), fusional amplitude plays a role in enforcing the patient's ability to maintain phoria. However, sufficient fusional amplitude does not guarantee fully functioning fusion if suppression is present during phoria.

Cited by 8 publications

References 16 publications

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

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

Longitudinal Rehabilitation of Binocular Function in Adolescent Intermittent Exotropia After Successful Corrective Surgery

Effect of Spectacle Lenses with Highly Aspherical Lenslets on Binocular Vision and Accommodation in Myopic Children with and without Intermittent Exotropia

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