PREDICTION OF EARLY-ONSET ESOTROPIA FROM COMPONENTS OF THE INFANTILE SQUINT SYNDROME

Purpose. To examine the association between components of the infantil e squint syndrome (ISS) and age of onset of esotropia among subjects i n the Cooperative Amblyopia Classification Study (CACS). Methods. Fift y subjects were classified retrospectively as having early-onset esotr opia (EOE) and 150 subjects were classified as having late-onset esotr opia (LOE), depending on whether symptoms of (or treatment for) strabi smus occurred before the first birthday or between tile first and nint h birthdays, respectively. The authors compared the degree to which la tent nystagmus (LN), dissociated vertical deviation (DVD), monocular a ssymetry of optokinetic nystagmus (MOKN), monocular asymmetry of smoot h pursuit (MSP), and perceived monocular speed bias (MSB) predicted EO E. Results. Slow-phase velocity of MOKN and MSP were faster in respons e to nasal than to temporal target motion. In contrast, MSB revealed t hat targets of equal velocity were perceived as moving faster temporal ly than nasally. The authors evaluated MOKN, MSP, and MSB as dichotomo us and as continuous predictors. Dichotomous analysis showed significa nt associations between DVD and asymmetries of MOKN in the preferred e ye of subjects with EOE, Univariate logistic regression models, based on DVD and LN as well as on continuous measures of MOKN, MSP, and MSB, revealed predictive power for all ISS components except LN. In the pr eferred eye, MSP asymmetry was tile strongest single predictor of EOE; multivariate analysis revealed that prediction of EOE improved with t he inclusion of DVD. Conclusions. Multivariate analysis indicated that dichotomous measures of DVD and continuous measures of MSP were indep endent predictors of EOE in a population of 8- to 40-year-old subjects with strabismus. In the preferred eye, MOKN asymmetry was predictive of EOE in the absence of information about MSP. Predictive values of a ll ISS components depended heavily on the baseline prevalence of EOE i n die target population.