Prevalence of Strabismus and Decreased Stereopsis in Parents of Children with Strabismus

OBJECTIVE: Strabismus affects 1-4% of children and shows strong familial predilections, although exact genetic mechanisms are not fully understood. Previous studies have noted abnormal binocularity in parents of children with strabismus. This study aimed to investigate the prevalence of strabismus and subnormal stereopsis in parents of children with various types of strabismus, including infantile, accommodative, non-accommodative esotropia, and exotropia. DESIGN: Prospective cohort study involving families enrolled in a genetics study at Boston Children's Hospital; retrospective review of a cohort of children without visual complaints presenting for screening eye examination. PARTICIPANTS: 2,164 parents of children with specific strabismus types were enrolled; 481 (303 mothers and 178 fathers) underwent orthoptic examination. 208 control children aged 8 or over with no visual complaints or history of strabismus. METHODS: Orthoptic examinations or self-reported survey data for diagnosis. MAIN OUTCOME MEASURES: Abnormal sensorimotor examinations among parents (strabismus, phoria, or decreased stereopsis), prevalence of strabismus and associated conditions on self-report, and alignment type correlation between parents and children. Additionally, stereopsis was evaluated in control children for a comparative baseline. RESULTS: Parents of children with strabismus had high rates of abnormal sensorimotor examinations: 50.2% of mothers and 60.1% of fathers demonstrated abnormalities. Specifically, 22.4% of mothers and 28.1% of fathers were diagnosed with strabismus, and 27.7% of mothers and 32.0% of fathers had conditions associated with strabismus (subnormal stereopsis, phorias 10PD or more, or a history of patching and/or exercises). There were no significant differences in rates of abnormal parental exam based on strabismus type of the child. Most parents shared the same deviation type with their children, signifying familial phenotypic inheritance. Stereopsis was subnormal in 14.9% of controls. CONCLUSIONS: This study highlights the familial nature of strabismus and high rate of abnormal stereopsis in parents of children with strabismus. This suggests that low stereopsis may be a subclinical form of strabismus. A notable discrepancy in self-reported and examined diagnosis underscores the need for clinical evaluations. Our findings suggest that low stereopsis could be used as a phenotype in large biobank genetic studies to allow greater understanding of strabismus, which is often neglected in eye genetic studies.