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Alexandra Benavente-Perez, Ann Nour, Luying Yan, Keisha Roden, Kathleen Abarr, David Troilo; Daily interruptions to hyperopic defocus can reduce induced eye growth in marmosets. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2327.
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To assess the effect that short daily interruptions to imposed hyperopic defocus have on the eye growth of marmosets, and to measure the effective refractive state during the interruption period.
A total of 20 marmosets were treated with -5D contact lenses on their right eyes for 12 weeks from the age of 10 weeks of age (left eyes wore plano controls). On-axis vitreous chamber depth (VC) was measured after four (T4), eight (T8) and twelve weeks of treatment (T12). Fifteen marmosets wore contact lenses continuously for 9hrs/day and five had both contact lenses removed for 30mins twice/day (mid morning and mid afternoon) during the first four and last four weeks of treatment. Vision during the interruptions was controlled by placing the marmoset in a primate chair at the center of a 1m radius cylinder with videos of animal scenes projected on the wall. Noncyloplegic Rx was measured at 5min intervals using an infrared video photorefractor (Power Refractor, MultiChannel System) while the marmosets were in the chair. Untreated marmosets (N=25) were used as controls.
At T4 the interocular difference in ocular growth rates in the interrupted lens-reared group was smaller than in the continuous lens reared group (mean±SE exp-con: -0.3±1.3 vs +3.6±1.0 µm/day, p<0.05) and similar to the untreated group (-0.2±0.4 µm/day, p=0.97). At T8, after both treatment groups worn -5D contact lenses continuously for 4weeks, their growth rates were the same (+2.8±0.7 vs +1.8±1.2 µm/day, p=0.47). At T12, after the second period of lens interruption, the growth rate in the interrupted lens-reared group was again smaller than in the continuous lens reared group growth, but did not reach significance (-0.07±0.8 vs +0.85±1.5 µm/day, p>0.05). While inside the cylinder, the marmosets experienced an overall relative myopic defocus of -2.07±0.63D during T4 that increased to -4.08±1.63 D during T12.
Daily brief interruptions to imposed hyperopic defocus prevent the increased rate of ocular growth triggered by -5D contact lenses in marmosets. The effects were stronger when the interruptions happened early during treatment than when the interruptions were applied to eyes that were already growing faster to compensate for imposed hyperopia.
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