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Ann Nour, Alexandra Benavente-Perez, David Troilo; Eye Growth and Changes in the Refractive State of Marmosets after Imposing Peripheral Myopia or Hyperopia using Bifocal Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3456.
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© ARVO (1962-2015); The Authors (2016-present)
The ability of the peripheral retina to process visual stimuli for the control of eye growth has been demonstrated in animal models using spectacle lenses to impose defocus on the periphery; however, eye movements will affect the amount of retinal defocus delivered to the periphery. In this study, bifocal contact lenses were used to impose more controlled myopic and hyperopic defocus to the retinal periphery of marmosets, and their effects on eye growth and refractive state were evaluated.
Marmosets were treated with two custom designed bifocal annular soft contact lenses over their right eyes (left eyes wore plano controls). Both designs had a 3mm central plano zone surrounded by +5D (AN+5, n=9) or -5D (AN-5, n=8) to lens edge (total diameter, 6.5mm), that provided a unifocal peripheral myopic or hyperopic hemifield of defocus of approximately 66 deg. Treatment began at 70 days and continued for 10 weeks. On-axis vitreous chamber depth (VC) and refractive state (Rx) were measured and compared to those in single vision negative (SVN, n=19) and positive (SVP, n=19) marmosets.
At the end of treatment, the AN+5 marmosets had relatively shorter VCs (mean±SE exp-con VC depth: -0.037±0.018mm, p=0.035; Rx: +0.23±0.43D, p=0.30; one-tailed paired t-tests); whereas the AN-5 marmosets had longer VCs in the experimental eyes (VC: +0.092±0.040mm, p=0.027; Rx: -0.07±0.41D, p=0.43). The interocular differences in VC differed statistically between AN+5 and AN-5 (p=0.015, two-tailed unpaired t-test), and were similar to those of SVP and SVN lens-reared animals (mean±SE exp-con SVP: -0.045±0.026mm; SVN: +0.135±0.054mm). While their refractive changes were not significant, in the AN+5 condition, 5 of 9 animals were more myopic in the experimental eye (mean±SE exp-con: Rx±SE-0.75±0.17D); whereas in the AN-5 condition, 5 of 8 were relatively more hyperopic in the experimental eyes Rx±SE: +0.59±0.21D).
Imposing myopia or hyperopia in the far peripheral retina of marmosets resulted in compensatory growth changes in vitreous chamber depth. Although the refractive error effects were variable and not as clear as in animals treated with single vision defocusing lenses, the effects on eye growth provide some support for the hypothesis that the retinal periphery can be manipulated with contact lenses. We are currently investigating the effects of imposing refractive error to larger areas of peripheral retina.
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