Relationship among clinical factors in childhood intermittent exotropia

Abstract

Purpose: To determine the relationships between stereoacuity, control of exotropia, and angle of deviation in children with intermittent exotropia (IXT).

Methods: Data collected for 652 participants 3 to <11 years of age with IXT meeting eligibility criteria for enrollment into one of two multicenter, randomized clinical trials were used to evaluate relationships between stereoacuity, control, and angle of deviation at enrollment.

Results: Any level of stereoacuity and angle of deviation could be accompanied by any level of control. Worse distance exotropia control was weakly associated with poorer distance stereoacuity (R = 0.26; 99% CI, 0.17-0.36) and larger angles of deviation at distance (R = 0.27; 99% CI, 0.17-0.36). Worse near exotropia control was weakly associated with poorer near stereoacuity (R = 0.17; 99% CI, 0.07-0.27) and moderately associated with larger angles of deviation at near (R = 0.37; 99% CI, 0.28-0.45). There was no association between stereoacuity and angle of deviation at distance (R = 0.07; 99% CI, -0.03 to 0.17) or at near (R = 0.02; 99% CI, -0.08 to 0.12).

Conclusions: Although weak and moderate associations were found between stereoacuity, control, and angle of deviation, a child may exhibit any combination of stereoacuity, control, and angle of deviation. The specific roles of control, stereoacuity, and angle of deviation in the diagnosis, management, and pathogenesis of IXT are unclear, and each appears to yield somewhat independent information.

FIG 1

Relationships between stereoacuity, control of exotropia, and angle of deviation between parameters measured at the same distance.

FIG 2

Suggested relationships between control, stereoacuity, and angle of deviation. The figure displays 6 potential relationships between stereoacuity, control of exotropia (control), and angle of deviation (angle) based on the results. A, Control may influence stereoacuity and angle. B, Angle and stereoacuity may influence control. C, Control may influence stereoacuity and may be noncausally associated with angle. D, Stereoacuity influences control. Control is noncausally associated with angle. E, Control influences angle and is noncausally associated with stereoacuity. F, Angle influences control. Control is noncausally associated with stereoacuity. Lines represent noncausal associations while arrows display causal associations.