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David Berntsen, Carl Kramer; Peripheral Defocus with Spherical and Bifocal Soft Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5455. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Peripheral myopic defocus has been hypothesized to slow the progression of myopia. We describe peripheral defocus when myopic eyes are corrected with spherical and center-distance multifocal soft contact lenses while looking at distance and near objects.
Twenty-five subjects with spherical contact lens-corrected refractive error of -0.50 to -6.00 DS participated. A modified open-field autorefractor was used to measure refractive error of the right eye while wearing a spherical soft contact lens (Biofinity) and a center-distance multifocal soft contact lens with a +2.50-D add (Biofinity Multifocal "D" Lens). Measurements were made centrally and along the horizontal meridian at ±20°, ±30° and ±40° from the line of sight both at near (30-cm demand) and at distance (under cycloplegia). Lens type and measurement starting location were randomized. Repeated-measures ANOVAs with post-hoc t-tests were used for analysis.
The mean (±SD) age and central spherical equivalent refractive error were 23.8 ± 1.3 years (range: 22 to 27 years) and -3.62 ± 1.56 DS, respectively. At distance, mean spherical equivalent refractive error (defocus) when wearing contact lenses was significantly more hyperopic with the spherical lens than with the multifocal lens (p<0.001). The multifocal lens resulted in peripheral myopic defocus at all locations. The largest difference in defocus between the spherical and multifocal lens occurred temporally with a difference of 2.35 D, and the smallest difference was 1.06 D (all p<0.05). When accommodating to a near target with each lens type, there was a myopic shift that was greater in the far periphery than at more central locations (p<0.001). Compared to the spherical lens at near, the multifocal resulted in more myopic defocus at three locations (range: 0.91 to 0.38 D; all p<0.05), more hyperopic defocus at two locations (range: 0.27 to 0.42 D; both p<0.05), and no difference at two locations.
Multifocal soft contact lenses resulted in peripheral myopic defocus at all locations measured while spherical lenses resulted in peripheral hyperopia when viewing at distance. Both lens types exhibited more similar effects on defocus when viewing a 30-cm near target. If myopic retinal defocus is able to slow axial eye growth in children, wearing center-distance multifocal contact lenses results in an optical profile that could be an effective method for slowing myopia progression.
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