Hypo-accommodation Responses in Hypermetropic Infants and Children
Résumé
Aims: Accommodation to overcome hypermetropia is implicated in emmetropisation. This study recorded accommodation responses in a wide range of emmetropising infants and older children with clinically significant hypermetropia to assess common characteristics and differences. Methods: A PlusoptiXSO4 photorefractor in a laboratory setting was used to collect binocular accommodation data from participants viewing a detailed picture target moving between 33cm and 2m. 38 typically developing infants were studied between 6-26 weeks of age and were compared with cross-sectional data from children 5-9 years of age with clinically significant hypermetropia (n=15), corrected fully accommodative strabismus (n=14) and 27 age-matched controls. Results: Hypermetropes of all ages under-accommodated compared to controls at all distances, whether corrected or not (p<0.00001) and lag related to manifest refraction. Emmetropising infants under-accommodated most in the distance, while the hypermetropic patient groups under-accommodated most for near. Conclusions: Better accommodation for near than distance is typical of emmetropization in hypermetropic infants and would support delay in correction. In contrast, hypermetropic children referred for treatment for reduced visual acuity are not likely to habitually accommodate to overcome residual hypermetropia left by an under-correction.
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