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N. C. Strang, B. Cagnolati, L. S. Gray, D. Seidel, M. Day; Longitudinal Investigation of Ocular Shape Changes During Refractive Development. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3963.
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© ARVO (1962-2015); The Authors (2016-present)
To characterise changes in ocular dimensions and refractive power longitudinally as a function of refractive error.
140 subjects (44 hyperopes (HYP), 61 emmetropes (EMM) and 35 myopes (MYO)), with an age range of 5 to 20 years participated with informed consent in the study. Baseline mean spherical refractive error (MSE) was between -5.88D and +3.45D. The following measurements were obtained at baseline and 2 years later: 1. Axial length centrally and 19 degrees horizontally and vertically using partial coherence interferometry (Zeiss IOLMaster) and 2. Central and peripheral refraction with an open-field infrared autorefractor (Shin-Nippon NVision-K 5001).
Mean baseline peripheral refraction in the MYO was significantly (p<0.05) less myopic (mean difference 0.32±0.73D) than central refraction, and the axial length was significantly shorter in both the horizontal (mean difference 0.34±0.17mm, p<0.01) and vertical (mean difference 0.16±0.14mm, p<0.01) meridian. A significant (p<0.01) myopic change in central MSE of -0.48±0.50D was found in the MYO group over the two year period. This was accompanied by a significant (p<0.01) increase in central axial length of 0.26±0.23mm. Mean peripheral refraction became significantly more myopic (mean difference 0.57±0.56D, p<0.01), and mean peripheral axial length increased in both the horizontal (mean difference 0.22±0.21mm, p<0.01) and vertical (mean difference 0.25±0.21mm, p<0.01) meridian. In the HYP group peripheral refraction was significantly less hyperopic (mean difference 0.66±0.85D, p<0.01) than central refraction and the axial length was significantly shorter in both the horizontal (mean difference 0.19±0.13mm, p<0.05) in the rate of refractive development between relative peripheral myopes and relative peripheral hyperopes.
The prolate shape found in myopic eyes is maintained during myopic growth as similar levels of expansion occur centrally and peripherally. The more spherical eye shape found in hyperopes is maintained during eye growth. Eye shape and peripheral retinal defocus do not appear to be strong causative factors in refractive development.
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