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L. E. Ernst, L. T. Sinnott, M. D. Bailey; Ciliary Body Thickness and the Chance of Becoming Myopic. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3953.
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To determine the relationship between the chance of becoming myopic and ciliary body thickness in a cross-sectional sample of emmetropic children.
The right eyes of 69 emmetropic children ages six to eleven years were measured. Outcome measures included cycloplegic autorefraction (spherical equivalent), cycloplegic measurements of ciliary body thickness at 2 mm posterior to the scleral spur, and axial length (IOLMaster). A discrete-time survival model for the chance of becoming myopic within four years was developed using data from the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study using age, refractive error, axial length and number of myopic parents. The model was then applied to the 69 emmetropic children. The relationship between the chance of developing myopia and ciliary body thickness was modeled with a repeated measures analysis of variance.
The mean ± SD age was 8.62 ± 1.40 years, refractive error was +0.71 ± 1.00 D and axial length was 23.20 ± 0.76 mm. The thickness of the ciliary body was significantly associated with chance of becoming myopic (p = 0.04). Modeled thickness estimates were 751.8µm for emmetropic children with no chance of becoming myopic (chance < 0.01), 797.0 µm for children with a little chance of becoming myopic (0.01 < chance < 0.10), and 806.3 µm for children with some chance of becoming myopic (chance > 0.10).
These data suggest that the ciliary body is probably increasing in thickness before myopia onset in a manner similar to how axial length increases prior to myopia onset. A longitudinal study is needed to confirm the temporal relationships between changes in ciliary body thickness, refractive error, axial length, and the onset of myopia.
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