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The Nepal longitudinal study: Biometric characteristics of developing eyes

Stewart, Alistair W.; Garner, Leon F.; Kinnear, Robert F.; Frith, Michael J.; Owens, Helen


Alistair W. Stewart

Leon F. Garner

Robert F. Kinnear

Michael J. Frith

Helen Owens
Senior Lecturer in Optometry


PURPOSE. To identify differences in potential biometric markers for predicting refractive error in school children. METHODS. Biometric data on 895 Tibetan children, aged 6 to 18 years, residing in Katmandu, Nepal, were collected biennially from 1992 to 2000. Measurements included cycloplegic autorefraction, A-scan ultrasonography, and video phacometry. Only those children who had been studied at least once at age 12 years or more were included in the analysis. Subjects were divided into two groups: a myopia group if the refractive error was myopic by more than -0.50 D and a nonmyopia group if the refractive error was maximally myopic by -0.50 D, expressed as a spherical equivalent error in the left eye. RESULTS. Biometric measures that differed significantly with increasing age between the two refractive groups included: anterior chamber depth + 0.012 mm/year (p = 0.014), anterior lens radius of curvature + 0.073 mm/year (p = 0.001), lens power -0.059 D/year (p = 0.082), lens thickness -0.005 mm/year (p = 0.02), and vitreous chamber depth + 0.084 mm/year (p < 0.001). Corneal radii of curvature of the myopic group were steeper at all ages by 0.09 mm (p < 0.001), but the rate of change with age was equivalent across the refractive groups. CONCLUSIONS. Compared with those who remained nonmyopic, children who developed myopia had a crystalline lens that was initially thicker and steeper, and a vitreous chamber that was initially shorter. With age, children who became myopic developed greater lens thinning, greater flattening of the anterior lens surface radius, and a greater increase in vitreous chamber depth than their nonmyopic counterparts. Copyright © 2006 American Academy of Optometry.


Frith, M. J., Kinnear, R. F., Stewart, A. W., Garner, L. F., & Owens, H. (2006). The Nepal longitudinal study: Biometric characteristics of developing eyes. Optometry and Vision Science, 83(5), 274-280.

Journal Article Type Article
Acceptance Date Feb 2, 2006
Publication Date May 1, 2006
Journal Optometry and Vision Science
Print ISSN 1040-5488
Publisher Lippincott, Williams & Wilkins
Peer Reviewed Peer Reviewed
Volume 83
Issue 5
Pages 274-280
Keywords myopia, ocular biometry, Tibetan children
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