Eighty-nine percent of the children, across all levels of GMFCS, had infantile-onset strabismus, as evident by markers for fusion maldevelopment in the first months of life: latent nystagmus, pursuit/OKN asymmetry, and DVD.
34 –36 The other 11% had onset after age 1 year and did not display these markers. Primary esotropia (ET) was present in 54% of the children and exotropia (XT) in 36% (the remaining 10% were dyskinetic). The angle of strabismus was stable (<10 PD variance; see Methods) in 76%, unstable in 14%, and dyskinetic in 10%. Dyskinetic strabismus was distinct in that it was present only in children with level 5 CP (
P < 0.01). Vertical misalignment, which included DVD, accompanying a horizontal heterotropia was also common. Vertical misalignment, across all levels of GMFCS, was detected in 52% of children. The children at different levels of GMFCS did not differ in gestational age or age at entrance into the study (ANOVA;
P = 0.9 and
P = 0.23, respectively).
Table 2 shows the frequency and type of ametropia, amblyopia, and fusion-maldevelopment gaze disorder in the subsets of children with esotropic, exotropic, or dyskinetic strabismus.