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J. R. Drover, L. M. Wyatt, D. R. Stager, Sr., E. E. Birch; The Teller Acuity Cards are Effective in Detecting Amblyopia. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2833. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Detection of amblyopia in infants and toddlers is challenging as the current clinical standard, fixation preference, yields poor sensitivity (~ 30%). Although grating acuity represents an alternative, reports indicate that it overestimates visual acuity in children with amblyopia. Here we examine whether the Teller Acuity Cards (TAC) can detect amblyopia effectively by testing children old enough to complete the gold standard, optotype acuity.
Grating acuity was assessed monocularly using the TAC following a staircase protocol in 71 children with unilateral amblyopia (age:6.3+3.1 yrs), 54 children with amblyogenic factors (strabismus, cataracts, ptosis, anisometropia) without amblyopia (age:7.7+4.3 yrs), and 28 children with no known vision disorders (age:8.7+2.4 yrs). Children also completed a crowded or linear optotype acuity test. Formal amblyopia diagnoses were based on an interocular difference of ≥0.2 logMAR in optotype acuity with ≥0.3 logMAR in the nonpreferred eye. Each child’s grating acuity was classified as normal/abnormal based on age-corrected norms and a standard normal interocular difference (IOD) of <0.3 logMAR. Sensitivity and specificity were calculated.
Among amblyopic eyes, grating acuity was superior to optotype acuity (0.26 v 0.53 logMAR, p<0.001), whereas grating and opotype acuities of fellow eyes did not differ (0.07 v 0.07 logMAR). Bland-Altman plots revealed that the grating acuity-optotype acuity discrepancy among amblyopic eyes was small (0.17 logMAR) for cases of moderate amblyopia (0.3-0.5 logMAR) but increased with increasing severity of amblyopia. Nevertheless, there was a significant correlation between grating and optotype acuity of amblyopic eyes (r=0.50, p<0.001) and between grating and optotype acuity IODs of amblyopic children (r=0.77, p<0.001). Furthermore, despite the acuity overestimation, most cases of amblyopia were detected by the TAC, yielding a sensitivity of 81% and a specificity of 71%. Sensitivity ranged from 73-86% across amblyopia subtypes (strabismic, anisometropic, mixed, deprivation).
Although our results confirm that grating acuity overestimates optotype acuity in amblyopic eyes, particularly in severe cases, most children with amblyopia scored outside the normal range. These results suggest that the TAC can be an effective clinical alternative for detecting amblyopia.
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