Abstract
Purpose: :
Children and young adults with cerebral palsy (CP) have an increased incidence of high refractive errors (Schenk-Rootlieb et al., 1992; Sobrado et al., 1999; Kozeis et al., 2007). Whilst in the developmentally normal population there is a strong association between refractive error and axial length there are no studies examining whether this relationship holds in CP. This study is the first to investigate the relationship between refractive error and ocular biometry in 44 children and young adults with CP.
Methods: :
Measures of refractive error, axial length (AL) and corneal curvature (CC) were attempted on 44 children and young adults with CP (aged 4-19 years). Refractive error was assessed using cycloplegic retinoscopy. AL was measured with the Zeiss IOLMaster and CC with the Nidek hand-held KM 500 autokeratometer. Data from the right eye were analysed.
Results: :
Refractive error was measured successfully in all subjects. Mean spherical equivalent (MSE) ranged from -7.125D to +6.375D. AL and CC were measured in 36 (82%) and 35 (80%) subjects respectively. AL ranged from 18.94 to 27.47mm: average CC ranged from 7.28 to 8.45mm. AL was significantly correlated with MSE refractive error (r=-0.91, p<0.0001). CC did not significantly influence refractive error (r=-0.11, p=0.51). AL/CC ratio was calculated and compared with refractive error, and also revealed a significant relationship (r=-0.92, p<0.0001), slightly strengthened by the inclusion of CC with AL data.
Conclusions: :
The relationship between refractive error and axial length in children and young adults with CP is similar to that in a developmentally normal population. Corneal power did not demonstrate an association with refractive error, again consistent with the literature. The aetiology of refractive error in CP is not due to a unique ocular biometric profile. Further investigation is required to determine why individuals with CP demonstrate high refractive errors.
Keywords: refractive error development • cornea: clinical science • optical properties