Cortical Deficits are Correlated with Impaired Stereopsis in Patients with Strabismus
Sida Xi1,2,3,4 · Yulian Zhou1,2,3,4 · Jing Yao1,2,3,4 · Xinpei Ye5 · Peng Zhang6 · Wen Wen1,2,3,4 · Chen Zhao1,2,3,41 Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China
2 State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200031, China
3 Key Laboratory of Myopia, Fudan University, Ministry of Health, Shanghai 200031, China
4 Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031, China
5 Department of Radiology, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China
6 State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
Abstract
In this study, we explored the neural mechanism underlying impaired stereopsis and possible functional plasticity after strabismus surgery. We enrolled 18 stereo-deficient patients with intermittent exotropia before and after surgery, along with 18 healthy controls. Functional magnetic resonance imaging data were collected when participants viewed three-dimensional stimuli. Compared with controls, preoperative patients showed hypoactivation in higher-level dorsal (visual and parietal) areas and ventral visual areas. Pre- and postoperative activation did not significantly differ in patients overall; patients with improved stereopsis showed stronger postoperative activation than preoperative activation in the right V3A and left intraparietal sulcus. Worse stereopsis and fusional control were correlated with preoperative hypoactivation, suggesting that cortical deficits along the two streams might reflect impaired stereopsis in intermittent exotropia. The correlation between improved stereopsis and activation in the right V3A after surgery indicates that functional plasticity may underlie the improvement of stereopsis. Thus, additional postoperative strategies are needed to promote functional plasticity and enhance the recovery of stereopsis.
Keywords
Stereopsis; Binocular disparity; Functional magnetic resonance imaging; Strabismus; Intermittent exotropia
