Altered Homotopic Connectivity in the Cerebellum Predicts Stereopsis Dysfunction in Patients With Comitant Exotropia

Abstract

Purpose: Comitant exotropia (CE) is a common eye disorder characterized by impaired stereoscopic vision and eye deviation. Previous neuroimaging studies demonstrated that patients with CE were accompanied by specific functional and structural abnormalities of the brain. However, the effect of impaired stereoscopic vision and eye deviation on interhemispheric homotopic connectivity remains unknown.

Methods: A total of thirty-six patients with CE (25 males and 11 females) and 36 well-matched healthy controls underwent magnetic resonance imaging scanning. The voxel-mirrored homotopic connectivity (VMHC) method was applied to assess the interhemispheric homotopic connectivity changes in patients with CE. Furthermore, the support vector machine method was applied to assess to differentiate patients with CE from healthy controls (HCs) with the VMHC maps as a feature.

Results: Compared with HCs, patients with CE showed significantly increased VMHC values in the bilateral cerebelum_ 8 and cerebelum_4_5. Moreover, we found that the VMHC maps showed an accuracy of 81.94% and an area under the curve of 0.87 for distinguishing the patients with CE from HCs.

Conclusion: Our study demonstrates that patients with CE showed interhemispheric homotopic connectivity changes in the cerebellum, which might reflect the neurological mechanisms of impaired stereoscopic vision and eye deviation in patients with CE.

Keywords: comitant exotropia; functional connectivity; functional magnetic resonance imaging; support vector machine; voxel-mirrored homotopic connectivity.

FIGURE 1

One-sample t-test results of VMHC maps within comitant extropia (CE) group (A) and HC group (B). Abbreviations: CE, comitant exotropia; HC, health control; and VMHC, voxel-mirrored homotopic connectivity.

FIGURE 2

Significant VMHC differences in the CE and HC group (A); the mean of altered VMHC values between patients with CE and HCs (B). Abbreviations: CE, comitant exotropia; HC, health control; VMHC, voxel-mirrored homotopic connectivity; and CER, cerebellum.

FIGURE 3

Classification results using support vector machine (SVM) based on VMHC values. Function values of two groups (class 1: CE group; class 2: HC group); (A). The ROC curve of the SVM classifier with an AUC value of 0.87 (B). Abbreviations: CE, comitant exotropia; HC, health control; VMHC, voxel-mirrored homotopic connectivity; ROC, receiver operating characteristic; SVM, support vector machine; and AUC, area under the curve.