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Jiayan Huang, Gui-Shuang Ying, Maureen G. Maguire, Graham E. Quinn, Marjean T. Kulp, Elise Ciner, Lynn A. Cyert, Agnieshka Baumritter; The Association between Anisometropia Measured by Vector Analysis and Unilateral Amblyopia in Preschoolers. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6330.
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To examine the association of unilateral amblyopia, inter-ocular acuity difference (IAD), and stereo-acuity (SA) with the degree of anisometropia as measured by vector analysis.
Monocular visual acuity (VA) (Electronic Vision Tester), SA (Random Dot E or Stereo Smile), and Refractive Error (Cycloplegic Retinoscopy) were measured in 3- to 5-year-old non-strabismic children (N=3894) participating in Head Start. Measures of anisometropia were inter-ocular differences in M (spherical equivalent), J0 (power in the vertical/horizontal meridians), J45 (power in the oblique meridians) and in VDD (vector diopter difference), which incorporates differences in sphere, cylinder and axis. Unilateral amblyopia was defined as >= 2 lines difference in VA. The proportion of amblyopia, mean IAD and SA were compared among different severity levels of anisometropia. Sensitivity, specificity and AUC (area under the ROC curve) were used to summarize the ability to identify children with amblyopia.
For each measure, greater magnitude of anisometropia is associated with a higher proportion with amblyopia, greater inter-ocular VA differences, and worse stereo-acuity (trend p-values < 0.01). Compared to when minimal anisometropia (< 0.35 VDD, 2% with amblyopia, 0.05 logMAR in mean IAD) is present, the percentage with amblyopia and the mean IAD increase significantly when VDD is 0.8-1.2D (10%, 0.07), 1.2-2D (19%, 0.11), 2-4D (28%, 0.13) and > 4D (66%, 0.39). The AUC for detecting amblyopia using VDD is 0.84 (95% CI: 0.81-0.87), which is significantly higher than using M (0.69, CI: 0.65-0.73), J0 (0.79, CI: 0.76-0.82), J45 (0.70, CI: 0.67-0.73), and J0/J45 combined (0.80, CI: 0.77 - 0.84) (all p-values < 0.01). Using VDD >= 0.75 D as an indicator for amblyopia leads to sensitivity of 0.64 and specificity of 0.81.
Among Head Start preschoolers, higher levels of anisometropia measured by vector analysis are associated with greater proportions with amblyopia, greater IAD and worse SA. Anisometropia measured by VDD provides greater discrimination of amblyopia than spherical equivalent or J0/J45 among preschoolers.
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