Peripheral Refraction in Myopic Children Wearing Orthokeratology and Gas-Permeable Lenses

The University of New South Wales, Sydney, New South Wales, Australia.
Optometry and vision science: official publication of the American Academy of Optometry (Impact Factor: 1.6). 04/2011; 88(4):476-82. DOI: 10.1097/OPX.0b013e31820f16fb
Source: PubMed


To investigate changes in peripheral refraction after orthokeratology (OK) and rigid gas-permeable (GP) lens wear in progressing myopic children and to compare these peripheral defocus changes with reported changes in adults wearing OK.
Sixteen myopic children subjects were fitted with an OK lens in one eye for overnight wear and a GP lens in the other eye for daily wear. Central and peripheral refraction were measured at baseline and then after 3 mo of lens wear.
At baseline, myopic children showed relative peripheral hyperopia compared with central refraction at and beyond 20° in the temporal visual field (VF) and 30° in the nasal VF. Three months of OK lens wear produced hyperopic shifts in refraction between 30° in the temporal VF and 20° in the nasal VF. Peripheral refraction was similar to center at all positions in the temporal VF while remaining significantly myopic at all locations in the nasal VF. No change in either central or peripheral refraction was found after 3 mo in the eye assigned for GP lens wear.
OK significantly reduced myopia in the central 20° VF in myopic children, converting relative peripheral hyperopia measured at baseline to relative peripheral myopia. These changes in children are similar to changes reported in myopic adults wearing OK lenses. No change in either central or peripheral refraction was found after 3 mo of daily GP lens wear. OK lenses can be used to induce myopic defocus in the periphery in myopic children and may thus provide a potential mechanism for myopia control.

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    • "Recent studies suggest that peripheral vision can influence axial length in human eyes, potentially altering the central refractive error and its development because of the emmetropization effect of eye growth. Conversion of relative peripheral hyperopia to relative peripheral myopia is a good method to limit the axial elongation that leads to myopia [26,35], and OK lenses appear to be an excellent option for achieving this objective. OK lenses appear to be a good tool to control high myopia. "
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    ABSTRACT: Many efforts have been invested in slowing progression of myopia. Among the methods, atropine administration and orthokeratology (OK) are most widely used. This study analyzed the efficacy of atropine and OK lens in controlling myopia progression and elongation of axial length. This retrospective study included 105 patients (210 eyes) who wore OK lenses and 105 patients (210 eyes) who applied 0.125% atropine every night during the 3 following period. Student t-test, linear regression analysis, repeated measure ANOVA, and Pearson's correlation coefficient were used for statistical analysis. The change in axial length per year was 0.28 +/- 0.08 mm, 0.30 +/- 0.09 mm, and 0.27 +/- 0.10 mm in the OK lens group, and 0.38 +/- 0.09 mm, 0.37 +/- 0.12 mm, and 0.36 +/- 0.08 mm in the atropine group for years 1, 2, and 3, respectively. Linear regression analysis revealed an increase in myopia of 0.28 D and 0.34 D per year, and an increase in axial length of 0.28 mm and 0.37 mm per year in the OK lens and atropine groups, respectively. Repeated measure ANOVA showed significant differences in myopia (p = 0.001) and axial length (p < 0.001) between the atropine and OK lens groups; in astigmatism, there was no significant difference in these parameters (p = 0.320). Comparison of increases in axial length in relation to baseline myopia showed significant correlations both in the OK lens group (Pearson's correlation coefficient, r = 0.259; p < 0.001) and atropine group (r = 0.169; p = 0.014). High myopia patients benefited more from both OK lenses and atropine than did low myopia patients. The correlation of baseline myopia and myopia progression was stronger in the OK lens group then in the atropine group. OK lens is a useful method for controlling myopia progression even in high myopia patients.
    BMC Ophthalmology 03/2014; 14(1):40. DOI:10.1186/1471-2415-14-40 · 1.02 Impact Factor
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    • "All of these systems have a varying potential to induce peripheral myopic defocus and therefore may be beneficial for myopia progression control. Orthokeratology alters the corneal front surface in a way such that the resultant optics produces a focused image at the central retina and the desired myopic defocus at the peripheral retina [17] [18]. Regular soft contact lenses have the potential to induce peripheral myopic defocus only if their power exceeds –6.00 D [19]. "
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    ABSTRACT: Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men; mean age 27.3 ± 3.2 years; range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.
    The Open Ophthalmology Journal 08/2012; OJOph(2-3):45-53. DOI:10.4236/ojoph.2012.23011
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