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Earl L. Smith, III, Li-Fang Hung, Ronald S. Harwerth; The Degree of Image Degradation and the Depth of Amblyopia. Invest. Ophthalmol. Vis. Sci. 2000;41(12):3775-3781.
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purpose. To determine whether the depth of monocular form-deprivation amblyopia
is dependent on the degree of retinal image degradation.
methods. Chronic monocular form deprivation was produced in nine infant rhesus
monkeys by securing one of three different strengths of diffuser
spectacle lenses in front of the treated eye and a clear zero-powered
lens in front of the fellow eye. Three infant monkeys reared with plano
lenses in front of both eyes provided control data. The treatment
lenses were worn continuously from approximately 3 weeks of age for
periods ranging between 11 and 19 weeks. When the monkeys were
approximately 18 months of age, psychophysical procedures were used to
measure the effects of the rearing procedures on the spatial contrast
sensitivity function for each eye.
results. The treated eyes of all nine diffuser-reared monkeys showed contrast
sensitivity deficits that were indicative of amblyopia. On average, the
interocular grating acuity difference increased systematically from 0.6
octaves for the weakest diffuser lens to 2.3 ± 0.7 and 3.5 ± 0.8 octaves for the intermediate and strongest diffuser lenses,
respectively. There was a close correspondence between the magnitude of
the amblyopic deficits and the reduction in retinal image contrast
produced by the diffuser lenses.
conclusions. The results demonstrate that the depth of monocular, nonstrabismic
amblyopia is strongly influenced by the degree of retinal image
degradation experienced early in life.
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