Volume 9, Number 3, Article 14, Pages 1-13 doi:10.1167/9.3.14 http://journalofvision.org/9/3/14/ ISSN 1534-7362
Influence of accommodation on off-axis refractive errors in myopic eyes
Andrew Whatham
Institute for Eye Research, Sydney, NSW, Australia, & School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia
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Frederik Zimmermann
University of Applied Sciences, Berlin, Germany
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Aldo Martinez
Institute for Eye Research, Sydney, NSW, Australia
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Stephanie Delgado
Institute for Eye Research, Sydney, NSW, Australia
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Percy Lazon de la Jara
Institute for Eye Research, Sydney, NSW, Australia
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Padmaja Sankaridurg
Institute for Eye Research, Sydney, NSW, Australia, & School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia
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Arthur Ho
Institute for Eye Research, Sydney, NSW, Australia, & School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia
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Abstract

Introduction: This study aims to understand off-axis refraction during accommodation and to identify whether the relative hyperopia generally observed in myopic eyes changes with accommodation. Method: Twenty bilateral myopes (18 to 33 years) between −0.50 D and −4.25 D (spherical equivalent) and astigmatism less than 1.25 D participated in this study. A soft contact lens was used to correct refractive error for all measurements. Non-cycloplegic autorefraction was measured at the fovea and 20°, 30°, and 40° eccentricities in the nasal and temporal retina at distances of 2 m, 40 cm, and 30 cm. Results: Peripheral refractive error, relative to central refraction, became less hyperopic with increasing eccentricity and with increasing accommodation. Lag of accommodation increased with accommodation (p < 0.001) shifting the image-shell backward relative to the retina. In the farther periphery, there was either no change in refractive error or increased myopic shifts with accommodation. Astigmatism increased with eccentricity and significantly increased in the farther eccentricities with accommodation (p < 0.001). Conclusion: Myopes display hyperopic shifts in the center and near peripheral field during near-viewing, while the farther periphery either remains unshifted or demonstrates a myopic shift. These results are due to the combined effect of lag of accommodation and an increased curvature of field during accommodation.

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History
Received July 18, 2008; published March 20, 2009
Citation
Whatham, A., Zimmermann, F., Martinez, A., Delgado, S., de la Jara, P. L., Sankaridurg, P., & Ho, A. (2009). Influence of accommodation on off-axis refractive errors in myopic eyes. Journal of Vision, 9(3):14, 1-13, http://journalofvision.org/9/3/14/, doi:10.1167/9.3.14.
Keywords
myopia, accommodation, eccentricity, off-axis, astigmatism, curvature of field
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