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KMID : 1159320070090040423
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Korean Journal of Vision Science
2007 Volume.9 No. 4 p.423 ~ p.440
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Correlation of asphericity and ocular components according to the change of spherical equivalent for elementary school students in Ilsan city during two years
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Chang Bong-Soon
Kim Jeong-Mi
Eom Chang-Deuk
Mah Ki-Choong
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Abstract
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To obtain reference data for contact lens fitting in clinics and for the design and manufacturing of contact lens for Korean young students, cycloplegic autorefraction, corneal topography(Oculus Co., Keratograph V 1.65, Germany) and A-scan ultrasonography (Sonomed A/B Scan 5500, USA) were performed on 66 eyes of 33 young students who were living in Ilsan city near Seoul(mean age of 9.01(1.16 yrs in 2004).
The change of spherical equivalent, corneal apical radius, axial length and corneal astigmatism during 2 years were -0.818±0.704 D(p = 0.000), -0.007±0.033 mm(p = 0.044) and 0.310±0.309 mm(p = 0.000), -0.024±0.367 D(p = 0.590) respectively. The asphericity(Q-value) of cornea increased toward negative value as it moved from apex to periphery. The change of corneal asphericity was 0.005±0.092 in 10° radius, 0.003±0.076 in 20° radius and -0.012±0.063 in 30° radius, but the differences were all no significance.
Asphericity were not correlated to spherical equivalent and axial length. In the myopic group, asphericity and corneal apical radius showed a low correlation(1st : r = -0.399, p=0.014, 2nd : r = -0.361, p = 0.028) and the change of two ocular components showed a low correlation(r = 0.410, p = 0.012). Asphericity and corneal astigmatism showed a significant correlation(1st : r = 0.354, p = 0.032, 2nd : r = 0.427, p = 0.008), but the change of two ocular components was not significantly correlate(r = -0.012, p = 0.945). While asphericity were not correlated to ocular componets in the nonmyopic
group.
Further studies are needed to fully understand the correlation corneal asphericity with the ocular components in young students during growing period on the myopic group and to apply this information for design and manufacture of contact lenses.
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KEYWORD
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asphericity, corneal shape, corneal topography, corneal apical radius, spherical equivalent
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