Visual Acuity and Disorders of Ocular Posture in Children With Cerebral Palsy

Abstract

Abstract: : Purpose: To assess visual acuity and disorders of ocular posture in children with different sub–types and severities of cerebral palsy (CP). Methods: 94 subjects with CP (aged 4–15 years) were recruited via the Northern Ireland CP Register (NICPR). The NICPR contains information regarding the CP sub–type and severity of all children in Northern Ireland diagnosed with CP. Whilst wearing appropriate refractive correction, binocular visual acuity was assessed objectively using the Cardiff Acuity Test. The presence and direction of strabismus were determined using the standard cover/uncover test and the Hirschberg Test. The presence of manifest and latent nystagmus were also noted. Subjects with ocular pathology, as determined by direct ophthalmoscopy (excluding nystagmus), were excluded from the present study (n=1). Data regarding the subject’s neurological status were derived from the NICPR. Results: Visual acuity was reduced, i.e <6/9, in 22.3% of subjects. One–way ANOVA demonstrated that subjects with ataxic CP, more severe motor impairments and more severe impairments (motor and intellectual) were at a greater risk for poor visual acuity (p<0.05). Examination of ocular posture revealed that 33 subjects were strabismic; 16 esotropes, 15 exotropes and three subjects with hypertropia (including one subject with both exotropia and hypertropia). These data included eight subjects with an alternating strabismus. Chi square analysis revealed that subjects with spastic CP were at a greater risk of strabismus (p=0.007). Statistical analysis demonstrated no significant association between the level of motor and intellectual ability and the presence of strabismus (p>0.05). Nystagmus was present in 10 subjects (10.5%), including four subjects with latent nystagmus. Chi square analyses demonstrated that those children with spastic CP and more severe motor and intellectual impairments were at a higher risk for nystagmus (p<0.05). Conclusions:CP significantly impacts upon visual acuity and binocular vision status in children. Poor visual acuity in the present study is associated with more severe motor and intellectual impairments. Therefore, it seems likely that the reduced visual acuity may be attributed to cortical visual impairment in addition to ametropic amblyopia and nystagmus.

Keywords: visual acuity • strabismus • nystagmus