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A Model of the Effect of Lens Development on Refraction in Schoolchildren

He, Ji C. PhD*

doi: 10.1097/OPX.0000000000001146
Original Investigations

SIGNIFICANCE The study provides a new theory on the mechanism underlying myopia development, and it could be useful in clinical practice to control myopia development in schoolchildren.

PURPOSE To model the effect of the crystalline lens on refractive development in schoolchildren.

METHODS The Zemax 13 was used to calculate Zernike aberrations and refractions across 50° horizontal visual fields. Optical effects of the anterior chamber depth, lens thickness, and radii of curvature of the lens surfaces on refractions were modeled. Refractive changes induced by lens development in emmetropic and myopic eyes, based on a previous longitudinal study from literature, were calculated.

RESULTS A lens thickness reduction with an anterior chamber depth deepening caused a hyperopic shift over the visual fields and even more at the periphery. Opposite effects were found when the lens was thinned without any change of the anterior chamber depth. While a flattening of the anterior lens surface produced hyperopic refractions overall, a posterior lens flattening caused a myopic shift at the periphery, but a hyperopic shift of the central refraction. In the myopic eye, lens development induced refractive change toward more hyperopic over the visual fields and more at the periphery.

CONCLUSIONS Lens thinning and lens axial movement participate in peripheral refractive development in schoolchildren, and lens development with a deeper anterior chamber depth and a flatter lens surface in the myopic eye could generate extra hyperopia over visual fields. The myopic lens development could be due to a backward movement of the lens, driven by a backward growth of the ciliary process, which might be a causative factor of myopia development.

New England College of Optometry, Boston, Massachusetts *

Submitted: August 4, 2016

Accepted: August 29, 2017

Funding/Support: The author has reported no funding/support.

Conflict of Interest Disclosure: The author has reported no conflict of interest.

Author Contributions: Conceptualization: JCH; Data Curation: JCH; Formal Analysis: JCH; Funding Acquisition: JCH; Investigation: JCH; Methodology: JCH; Project Administration: JCH; Resources, Software: JCH; Supervision: JCH; Validation: JCH; Visualization: JCH; Writing – Original Draft: JCH; Writing – Review & Editing: JCH.

© 2017 American Academy of Optometry