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Pauline Kang, Paul Gifford, Helen A Swarbrick; Refraction along the vertical meridian in different refractive groups. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2726.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate differences in refraction along the vertical meridian in emmetropes and myopes
31 subjects (age range 18-33 years; 7M, 24F) were enrolled and stratified into two groups based on their central refractive error. Subjects with spherical equivalent refraction (M) between +0.50 and -0.50DS were categorized as emmetropes and those with M between -0.51 and -6.00DS as myopes. Central and peripheral refraction along the vertical meridian was measured at 10°, 20° and 30° along the superior and inferior visual fields using the IVS Discovery aberrometer. Repeated measures ANOVA and posthoc t-tests with Bonferroni correction were used to analyze differences in refraction along the vertical meridian. A p-value of 0.05 was used to denote statistical significance.
There was a significant difference in vertical refraction profiles between emmetropes and myopes (F=-4.741, p=0.003). Refraction was significantly more myopic compared to center at all positions along the vertical meridian in the emmetropic group except at 10° in the superior (p=0.156) and inferior (p=1.000) visual fields. There was no asymmetry in refraction between the superior and inferior visual fields (p>0.05). In contrast, myopes demonstrated no significant difference in peripheral refraction values from center along the vertical meridian (F=0.641, p=0.566).
Differences in peripheral refraction profiles were found between emmetropes and myopes along the vertical meridian. Furthermore, peripheral refraction profiles along the vertical meridian in both emmetropes and myopes were different to refraction profiles reported previously in these groups along the horizontal meridian. These findings suggest that if peripheral retinal defocus is the driver for refractive error development in humans, induction of myopic peripheral defocus rather than correction of hyperopic peripheral defocus may be necessary for myopia control.
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