Abstract
Introduction: Approximately 20% of children with hyperopia greater than +3.5D develop accommodative esotropia. How do strabismic children differ from the 80% with aligned eyes? Infants and young children experience changing accommodation and vergence demands due to emmetropization and head growth. Typically developing young children and pre-presbyopic adults demonstrate vergence adaptation to extra demands in maintaining eye alignment (in both convergent and divergent directions). This study asked whether vergence adaptation differed between hyperopes with and without a history of strabismus. Methods: The hyperopic participants were children and pre-presbyopic adults with spherical dquivalent refractive error ≥+3D in at least one eye and cylinder power ≤2D. They were compared to age-matched emmetropes. Vergence adaptation was assessed using changes in heterophoria after subjects viewed through a 6pd prism binocularly for four 1-min intervals. Eccentric photorefraction and Purkinje image eye tracking were used to monitor accommodation and eye alignment at 50Hz. All participants were tested with base in prisms requiring divergent adaptation. Results: Of 17 hyperopic participants (3.6-21.9 years of age, Mean 8.0, SD 4.9), 7 currently aligned with a history of strabismus showed -12% to 70% adaptation (Median 37%, IQR 2%-65%) and 5 generated < 50% adaptation; 10 hyperopes with no strabismus history adapted by -17% to 86% (Median 64%, IQR 29%-72%), with 3 showing < 50% adaptation. The age-matched emmetropes showed 2% to 118% adaptation (Median 72%, IQR 35%-81%), with 3 of 11 showing < 50% adaptation. Accommodation responses were monitored in each trial. Conclusion: These data suggest that strabismic hyperopes are more likely to have poor vergence adaptation. After a larger clinical trial, this factor could identify those at higher risk for refractive esotropia.
Meeting abstract presented at VSS 2018