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A. Nour, A. Benavente-Perez, D. Troilo; The Effect of Simultaneous ±5 D Defocus Imposed by Multizone Soft Contact Lenses on Eye Growth and Development of Refractive State in Marmosets. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1728.
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© ARVO (1962-2015); The Authors (2016-present)
Earlier studies showed that the common marmoset, a New World primate, like other animal models studied, can compensate for both imposed myopic or hyperopic retinal defocus by changes in eye growth and refractive state. This study determines how simultaneous exposure to myopic and hyperopic defocus affects axial growth and refractive state in marmosets.
Four marmosets were reared with a dual-power multizone lens over one eye and a plano lens over the fellow (control) eye. Lens treatment began at 10 weeks of age (mean starting refractive state: 0.23D±1.30D) and continued for 10 weeks. The lenses had two alternating powers (-5D/+5D) arranged in concentric zones centered around a -5D central zone that gave an approximately 50:50 ratio of surface area for a 2.8 mm pupil (average diameter of marmoset pupils). The effects of multizone lenses on the vitreous chamber depth and refractive state were measured and compared to those from earlier studies on marmosets reared with single vision lenses of -5D or +5D.
After 10 weeks of lens treatment, in 3 of the 4 marmosets, the multizone lens treated eyes were shorter and more hyperopic compared to the plano control eye (exp-con: VC depth, mean -0.041 mm, range -0.059 to -0.026 mm; refractive state, mean +1.71D, range +0.69D to +2.71D). These effects were similar to those seen in marmosets treated with single vision positive lens for comparable periods (exp-con: VC depth, mean -0.096 mm, range -0.287 mm to +0.063 mm; refractive state, mean +1.56D, range -0.46D to +3.72D). The fourth animal examined developed myopia in both eyes, but with relatively more in the lens treated eye (exp-con: VC depth, +0.122 mm; refractive state, -3.81D).
This study indicates that when retinal defocus of opposite sign is imposed simultaneously on the primate retina, myopic defocus appears to dominate in most, but not all, of the eyes tested thus far. These results suggest that properly balanced multizone contact lenses may be an effective treatment for preventing, or even reversing, the development of myopia.
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