Timing of Surgery for Infantile Esotropia in Humans: Effects on Cortical Motion Visual Evoked Responses
Christina Gerth 1,
Giuseppe Mirabella 1,
Xiaoqing Li 2,
Tom Wright 2,
Carol A. Westall 1,
Linda Colpa 2,
and
Agnes Wong 3*
1 Department of Ophthalmology, The Hospital for Sick Children - Toronto, Toronto, Canada; Ophthalmology and Vision Science, University of Toronto, Toronto, Canada
2 Department of Ophthalmology, The Hospital for Sick Children - Toronto, Toronto, Canada
3 Department of Ophthalmology, The Hospital for Sick Children - Toronto, Toronto, Canada; Ophthalmology and Vision Science, University of Toronto, 555 University Ave, Toronto, M5G1X8, Canada
* To whom correspondence should be addressed. E-mail: agnes.wong{at}utoronto.ca.
 |
Abstract |
|---|
Purpose: Infantile esotropia is associated with maldevelopment of cortical visual motion processing, manifested as directional asymmetry of motion visual evoked potentials (mVEPs). The purpose of this study was to determine whether early surgery at or before age 11 months could promote the development of cortical visual motion processing in human infants, as compared to standard surgery at age 11-18 months.
Methods: Sixteen children with a constant, infantile esotropia 
30 prism diopters and onset before age 6 months were recruited prospectively. Eight of them underwent early surgery at 
11 months of age, and eight underwent standard surgery at 11-18 months of age. Seven age-matched normal subjects served as controls. At 2 to 2.5 years of age, mVEPs were measured during monocular viewing of a grating that shifted between two positions with a lateral displacement of 90° at 10 Hz. Nasotemporal mVEP asymmetry was assessed by an amplitude "Asymmetry Index", and by the presence of a significant interocular phase difference.
Results: The mean Asymmetry Index and interocular phase difference in the early surgery group were comparable to that in age-matched controls, and they were significantly lower than those in the standard surgery group.
Conclusions: Early surgery for infantile esotropia promotes the development of cortical visual motion processing, whereas standard surgery is associated with abnormal mVEPs. Our results provide additional evidence that early strabismus repair is beneficial for cortical development in human infants.
Key Words:
strabismus, visual evoked potential, surgery
