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Baskar Arumugam, Li-Fang Hung, Chi-ho To, Padmaja Sankaridurg, Earl L Smith; The Effects of Peripheral Simultaneous Competing Defocus Signals on Emmetropization in Infant Rhesus Monkeys. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5512.
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© ARVO (1962-2015); The Authors (2016-present)
In the presence of simultaneous competing defocus signals across the entire retina, emmetropization is dominated by the more anterior focal plane. The aim of this study was to determine how simultaneous competing defocus signals restricted to the periphery influence refractive development.
Starting at 3 weeks of age, infant monkeys were reared with binocular dual-focus (Fresnel design) spectacles that had central zones of zero power surrounded by concentric annular zones of alternating powers of +3.0 D and 0 D (+3/pl). The widths of the annular zones were constant and equal, but the diameters of central zero-power zones were varied from 2 mm to 6 mm (n≥6 per group). The monkeys wore the treatment lenses continuously until 150±2.3 days. Refractive status, corneal power and axial dimensions were assessed every 2 weeks throughout the lens rearing period. Comparison data were obtained from monkeys reared with binocular full field +3D lenses (FF+3D, n=6) and from 34 monkeys reared with unrestricted vision.
The median refractive errors for the right eyes of animals reared with the dual focus lenses with central zero-power-zone diameters of 2 (+5.25 D), 4 (+5.60 D), and 6 mm (+3.50 D) were similar to those for the FF+3D animals (+4.63 D, p=0.11 to 0.27), but more hyperopic than those in control animals (+2.50 D, p=0.0002 to 0.01). The average vitreous chamber depths for infants reared with dual focus lenses were also shorter than those for controls (9.82±0.30 mm vs 9.31±0.30 mm for +3/pl 2mm, p=0.0001; 9.43±0.21 mm for +3/pl 4mm, p=0.005; 9.58±0.56 mm for +3/pl 6mm, p=0.09). The median ametropia for the +3/pl 6mm group was significantly less hyperopic than that for animals reared with central zones of 2 (p=0.04) or 4 mm (p=0.02), however there were no significant differences between the dual-focus lens groups in either the average vitreous chamber depths or in the changes in vitreous chamber depth that took place during the lens-rearing period (p=0.08 to 0.52).
The results demonstrate that imposing simultaneous, relative myopic defocus in the periphery can effectively slow axial elongation and produce hyperopic shifts in central refraction. However, the more of the visual field that is affected by competing relative myopic defocus, the larger and more consistent the hyperopic shifts in the central ametropias.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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