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LA Jones, GL Mitchell, DO Mutti, NE Friedman, ML Moeschberger, K Zadnik; Growth of Ocular Components as a Function of Refractive Error Groups . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2025.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: An important question related to refractive error development is whether the ocular components grow in similar ways as a function of refractive error. Growth curves were generated from the Orinda Longitudinal Study of Myopia (OLSM) to compare ocular components among emmetropes, hyperopes and myopes. Methods: OLSM subjects seen between 1989 and 1996 with at least three annual study visits were included in the analysis. Refractive error was defined as follows: myopia at least –0.75 D in both meridians at any visit, hyperopia at least +2.00 D in both meridians at any visit, and emmetropia between –0.75 D and +1.00 D at all visits. Growth curves were generated using mixed models in SAS to determine the best fitting model for the emmetropic eyes. The functional forms from the emmetropes were applied to the myopes and hyperopes to create curves. The resulting curves were then compared to the emmetropes. Results: Five hundred twelve subjects were available for analysis, 140 myopes, 33 hyperopes, and 339 emmetropes. At the first visit, hyperopes were younger, with shorter mean axial length, and higher calculated lens power than both emmetropes and myopes, and lower corneal power than the myopes. The axial length growth curve shape for the hyperopes (p-value testing growth curve shape= 0.0254) was significantly different from the emmetropes as was the myopes growth curve shape (p < 0.0001). The myopic eyes grew faster than the emmetropic eyes. Growth curve shapes for lens thickness, Gullstrand and calculated lens power, and lens refractive index did not differ between emmetropes and either of the other two groups. Conclusion: Hyperopic eyes had similar growth curves compared to the emmetropes for 7 of 9 ocular components, but on average, they began growing from a different position (e.g., shorter eye with flatter cornea). The axial length curve shape for hyperopic eyes was significantly different from that of emmetropes though differences appear minor. The myopic growth curve function indicates that these eyes start from a similar place and grow faster than the emmetropic eye.
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