Altered Functional Connectivity of the Primary Visual Cortex in Adult Comitant Strabismus: A Resting-State Functional MRI Study

ABSTRACT

Purpose: The aim of this study was to examine the functional connectivity between the primary visual cortex and other cortical areas during rest in normal subjects and patients with comitant strabismus using functional magnetic resonance imaging (fMRI).

Methods: A prospective, observational study was conducted. Ten patients with comitant exotropia and eleven matched healthy subjects underwent resting-state fMRI with their eyes closed. Resting-state fMRI was performed using a 3.0 T MR scanner. The primary visual cortex was subdivided into anterior and posterior subdivisions. The resting-state functional connectivities within the primary visual cortex and between the primary visual cortex and other cortical areas were calculated for each group and compared between the strabismic and normal control groups. fMRI data were analyzed using Statistical Parametric Mapping software and Analysis of Functional NeuroImages software.

Results: Compared with the normal controls, patients with comitant strabismus had increased functional connectivity between the posterior primary visual cortex and other cortical areas, especially the visual cortex [Brodmann area 19 (BA19)] and other oculomotor regions, such as the frontal eye field (BA6).

Conclusions: The fMRI results suggest that ongoing and permanent cortical changes occur in patients with comitant strabismus. Disrupted brain functional connectivities are associated with abnormal eye movement and loss of stereopsis. Our study provides a neurological basis for understanding the pathophysiology of comitant strabismus, which may prompt new areas of research to more precisely define this basis and extend these findings to enhance diagnosis and treatment.

KEYWORDS:

• Functional connectivity
• primary visual cortex
• comitant strabismus
• resting-state
• functional magnetic resonance imaging (fMRI)

Author contributions

Conceived and designed the experiments: X.Y., X.L. and T.J. Performed the experiments: X.Y., S.S., K.D., and Y.L. Analyzed the data: Y.W., X.Y., L.X., and Y.Z. Contributed reagents/material/analysis tools: Y.W., Y.Z., Y.L. and T.J. Wrote the manuscript: X.Y. and X.L. All authors reviewed the manuscript.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Role of the funders/sponsor

The funding sources had no role in the design and conduct of the study, collection and analysis of the data, or preparation and approval of the manuscript.

Patient consent

All participants provided informed consent.

Ethics approval

The Medical Research Ethics Committee of the Zhongshan Ophthalmic Center, Sun Yat-sen University.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was supported by grants JCYJ20150730150557658 and JCYJ20170413143051465 from the Research Foundation of Science and Technology Plan Project, Shenzhen, China; grants 2012B061700084, 2013B020307004, 2015A020212002 and 2016A020216002 from the Research Foundation of Science and Technology Plan Project, Guangdong, China; grant 2014A030310084 from the Natural Science Foundation of Guangdong; and grant 81500708 from the National Natural Science Foundation of China.