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Stereoacuity may be partially due to similarity in refractive errors between eyes
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A large prospective study of Native American children with a high prevalence of astigmatism has found that increased differences in best corrected interocular acuity may be related to both the quantity and kind of refractive error difference between eyes.
"Disruption of best corrected random dot [stereoacuity] occurs with smaller interocular differences than those producing an increase in [interocular acuity difference], suggesting that the development of [stereoacuity] is particularly dependent on similarity of the refractive error between eyes," the study authors said in the October issue of Investigative Ophthalmology & Visual Science.
Velma Dobson, PhD, and colleagues at the University of Arizona in Tucson assessed refractive errors, best corrected monocular visual acuity, best corrected stereoacuity and anisometropia among 972 children from the Tohono O'odham tribe who were between 4 and 13 years of age. Specifically, anisometropia was calculated in clinical notation for spherical equivalent and cylinder, as well as in two forms of vector notation that accounted for interocular differences in both axis and cylinder magnitude.
The investigators found that 415 of these children (42.7%) had 1 D or more of astigmatism in one or both eyes.
Interocular difference and presence of amblyopia were significantly elevated in children with 1 D or more of hyperopic anisometropia and between 2 D and 3 D of cylinder anisometropia.
Stereoacuity decreased significantly with 0.5 D or more of hyperopic, myopic or cylinder anisometropia, the authors noted.
Vector notation results showed that stereoacuity was disrupted at lower values of anisometropia than those associated with increases in interocular acuity difference and amblyopia, according to the study.