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J. Shen, C. Clark, P.S. Soni; Peripheral Refraction Across Horizontal Visual Field With And Without Contact Lenses . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1174.
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It has been suggested that peripheral refraction may effect development of refractive error. For example over corrected peripheral refraction in myopes may provide a stimulus for local compensatory eye growth. A few studies have characterized status of peripheral refraction in ametropic eyes. An attempt has been made to model the effect of spectacle lens correction on peripheral refraction. However there is no empirical data to show the effect of spectacle or contact lens correction on peripheral refractive error. The purpose of this study is to determine the central and peripheral refraction in uncorrected and corrected (contact lenses) adult myopic eyes.
The Hartmann–Shack technique was used to measure the central and peripheral refractive error at 10° intervals out to ±50° in the nasal and temporal periphery along the horizontal meridian. Data were collected on 3 eyes, two with low and one with high myopia. A measure of spherical equivalent power was used as the retinal defocus. The experiment was repeated with contact lenses of various powers which either fully, partially or overcorrected the ametropia.
In an uncorrected eye there is no significant difference in spherical equivalent correction within 10° of the center. Beyond this point, there is a hyperopic shift which increases with eccentricity. With soft contact lenses of varying corrective power, the change in central and peripheral refractive correction is a measure of the lens power. With contact lenses, the central 10° continues to show no difference with changing power. However, the refraction at peripheral locations out to 50° shows a slightly increased rate of hyperopic shift compared to that noted in uncorrected eyes. Astigmatism increased peripherally in all eyes, increasing especially rapidly beyond 20° as has been reported by a number of earlier investigators.
In this study we are able to demonstrate that peripheral refractive error data can be collected out to 50° nasally and temporally with the Hartmann–Shack technique. In addition, we have demonstrated that peripheral refractive data can be collected with soft contact lenses. However the current data shows, in these low and moderate myopes, that the peripheral refraction tends to be more hyperopic with and without correction (soft contact lenses). Additional subjects will be added as we proceed with this study.
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