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Donald O. Mutti, Robert I. Sholtz, Nina E. Friedman, Karla Zadnik; Peripheral Refraction and Ocular Shape in Children. Invest. Ophthalmol. Vis. Sci. 2000;41(5):1022-1030.
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purpose. To evaluate the relation between ocular shape and refractive error in
methods. Ocular shape was assessed by measuring relative peripheral refractive
error (the difference between the spherical equivalent cycloplegic
autorefraction 30° in the nasal visual field and in primary gaze) for
the right eye of 822 children aged 5 to 14 years participating in the
Orinda Longitudinal Study of Myopia in 1995. Axial ocular dimensions
were measured by A-scan ultrasonography, crystalline lens radii of
curvature by videophakometry, and corneal power by videokeratography.
results. Myopic children had greater relative hyperopia in the periphery
(+0.80 ± 1.29 D), indicating a prolate ocular shape (longer axial
length than equatorial diameter), compared with relative peripheral
myopia and an oblate shape (broader equatorial diameter than axial
length) for emmetropes (−0.41 ± 0.75 D) and hyperopes
(−1.09 ± 1.02 D). Relative peripheral hyperopia was associated
with myopic ocular component characteristics: deeper anterior and
vitreous chambers, flatter crystalline lenses that were smaller in
volume, and steeper corneas. Lens thickness had a more complex
association. Relative peripheral hyperopia was associated with thinner
lenses between refractive error groups but changed in sign to become
associated with thicker lenses when analyzed within each refractive
error group. Receiver operator characteristics analysis of the ocular
components indicated that vitreous chamber depth was the most important
ocular component for characterizing the myopic eye, but that peripheral
refraction made a significant independent contribution.
conclusions. The eyes of myopic children were both elongated and distorted into a
prolate shape. Thinner crystalline lenses were associated with more
hyperopic relative peripheral refractions across refractive error
groups, but failure of the lens to thin may account for the association
between thicker lenses and more hyperopic relative peripheral
refractions within a given refractive group. Increased
ciliary–choroidal tension is proposed as a potential cause of ocular
distortion in myopic eyes.
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