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Nevin Wadie El-Nimri, Christine Frances Wildsoet, ; The Effect of Discontinuous Wear of 2-zone Concentric Bifocal Spectacle Lenses on Refractive Error Development & Eye Growth in Young Chicks. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5842.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize in young chicks the myopia control effects of two-zone, distance or near center concentric multifocal lens designs worn on an alternate day schedule interleaved with standard single vision corrective lenses.
Monocular -10 Diopter (D) single vision (SV) lenses were worn by ten-day-old chicks for 4 days to induce myopia, after which the SV lenses were replaced by one of 2 multifocal lens designs (-10 D center/ -5 D periphery, MFDC) or -5 D center/ -10 D periphery (MFDP)) every other day for a total of 6 days. A control group wore -10 D SV lenses every day. A minimum of 4 birds was included in each treatment group. Refractive error and axial ocular dimensions were monitored every three days with retinoscopy and high frequency A-scan ultrasonography respectively.
The MFDC lens had greater myopia control effects than MFNC lenses although both groups recorded less myopia than the SV group and intergroup differences in on-axial dimensions were consistent with refractive errors. Mean baseline interocular optical axial length differences (± SD) were 0.29 ± 0.14 mm (SV), 0.26 ± 0.14 mm (MFNC), and 0.32 ± 0.17 mm (MFDC). After 6 days of lens wear, equivalent values were 0.46 ± 0.27 mm (SV), 0.39 ± 0.19 mm (MFNC), and 0.28 ± 0.17 mm (MFDC). Mean interocular refractive error differences (± SD) on day 6 were -12.18 D ± 1.77 (SV), -11.01 ± 1.14 D (MFNC), and -7.60 ± 0.97 D (MFDC) compared to baseline values of -12.32 ± 0.95 D (SV), -12.17 ± 1.56 D (MFNC), and -12.48 ± 0.41 D (MFDC).
The results demonstrate that discontinuous wear of multifocal lenses, e.g., every other day, interleaved with standard single vision correction of refractive errors, may be sufficient to control the progression of myopia.
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