The accommodative process in children with cerebral palsy: different strategies to obtain clear vision at short distance.

AIM: Accommodation is the ability of the eye to change focus in order to maintain a sharp image of objects at various distances. The accommodative process is largely unknown in children and requires new assessment techniques. The aim of the study was to investigate this process in children with and without cerebral palsy (CP).

METHOD: In a descriptive case-control study, children with CP (n=15; nine females, six males; median age 14y) and 21 typically developing children (11 females, 10 males; median age 12y) underwent standard ophthalmological examination and examination by the PowerRefractor. Six of the children had spastic bilateral CP, five had spastic unilateral CP, and four had dyskinetic CP. The children's Gross Motor Function Classification System (GMFCS) levels were as follows: level I, seven children; level II, two children; level III, three children; and level IV, three children. The PowerRefractor measures accommodation in response to minus lens stimuli. Continuous measurements of refraction/accommodation, eye position, and pupil size are obtained. The Kruskal-Wallis analysis of variance (ANOVA) and Mann-Whitney U test were used for between-group analysis (α=0.05), and Friedman ANOVA was used for within-group analysis.

RESULTS: The stimuli-response gain (input/output) was approximately 80% in typical children inducing a focusing error (0.2-0.5D) increasing with minus lens power. Children with CP accommodated significantly less (gain: ~30%; p<0.001), inducing a larger focusing error (1.1-1.7D) increasing with minus lens power. The accommodative response was slower and more variable in children with CP. The pupil response did not mirror the accommodative response.

INTERPRETATION: Children with CP exhibit problems in generating an appropriate accommodative response. This can affect everyday living and reading skills.