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Vidhya Subramanian, Eileen E. Birch; Ocular Biometric Characteristics of Emmetropization in Infantile Esotropia. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3906.
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Emmetropization in infantile esotropia (ET) has been shown to be delayed (Birch et al 2010). Using cycloplegic retinoscopy, children with infantile ET were shown to have persistent mild to moderate hyperopia from infancy until 7 years, and then experience a myopic shift at around 8 years of age, which continues until at least 12 years of age. Here we examine the ocular biometric characteristics of emmetropization in infantile ET to determine which ocular components contribute to the myopic shift.
LENSTAR® ocular biometric measurements were obtained from 20 children with infantile ET and 43 normal controls from 3-17 years of age. Axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) were compared between the two groups. Averaged data (5 measurements per eye) from right eyes were analyzed.
Children with infantile ET between 3 and 7 years old had significantly shorter AL (mean = 21.8mm) than normal controls (mean = 22.66mm; p = 0.04). However, no significant difference in AL between infantile ET (mean = 22.91mm) and normal controls (mean = 23.43mm; p=0.11) was found in children older than 7 years. No significant difference was seen in ACD or LT between the two groups in either age group. Beyond 7 years of age, the infantile ET group showed a myopic shift of 0.23 mm/yr and the normal controls experienced a myopic shift of 0.13 mm/yr (p>0.05). No significant change in axial length was seen between 3 and 7 years of age in either the infantile ET group or in normal controls.
Ocular biometry results support the previous finding that late emmetropization occurs in infantile ET. Although children with infantile ET do not undergo the infantile loss of hyperopia that normally characterizes emmetropization, they do experience axial elongation beginning at 8 years of age similar to the axial elongation related myopic shift seen in juvenile myopia. Although the vision-dependent mechanisms that influence emmetropization during infancy and the onset of myopia in later childhood are often considered to reflect the same underlying mechanism, in infantile ET we observed dissociation between these two phases of eye growth.
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