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Eric P. Andrade, Paula Y. Sacai, Adriana Berezovsky, Solange R. Salomao; Anisometropic And Strabismic Amblyopia Assessed By Grating And Optotype Acuity. Invest. Ophthalmol. Vis. Sci. 2011;52(14):403.
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© ARVO (1962-2015); The Authors (2016-present)
Our purpose is to compare the ability to diagnose amblyopia using two different types of visual tasks - grating and optotype acuity.
A group of 36 patients (17 females) with clinically defined amblyopia (interocular best-corrected acuity difference of at least 2 lines in Snellen chart): 20 with strabismus, 11 with anisometropia and 5 with a combination of both was tested. Age ranged from 5 to 14 years (mean 8.6±2.3 years, median 8 years). Grating acuity was measured with sweep visually evoked potentials and optotype acuity was measured with a retro-illuminated ETDRS tumbling-E chart. Visual acuities and inter-ocular acuity differences (IAD) were calculated in logMAR.
Overall, grating acuity (mean 0.09±0.1 logMAR, median 0.08 logMAR) was comparable with optotype acuity (mean 0.1±0.17 logMAR, median 0.0 logMAR) in the fellow eye and it was significantly better (mean 0.43±0.26 logMAR, median 0.4 logMAR) in the amblyopic eye when compared to optotype acuity (mean 0.62±0.3 logMAR, median 0.58 logMAR; p=<0.001). In strabismic amblyopes significantly worse grating acuity (mean 0.07±0.03 logMAR, median 0.08 logMAR) was found in the fellow eye (p=0.018) when compared to optotype acuity (mean 0.04±0.06 logMAR, median 0.0 logMAR). Grating acuity in the strabismic amblyopic eye was significantly better (mean 0.43±0.25 ogMAR, median 0.36 logMAR) when compared to optotype acuity (mean 0.64±0.30 logMAR, median 0.6 logMAR; p=<0.001). In the anisometropic amblyopia group, grating acuity (mean 0.12±0.14 logMAR, median 0.06 logMAR) was comparable to optotype acuity (mean 0.15±0.25 logMAR, median 0.0 logMAR) in the fellow eye, and it was better (0.43±0.29 logMAR, median 0.41 logMAR) in the amblyopic eye (paired t-test; p=0.009). Statistically larger IADs were found in optotype acuity compared with grating acuity overall (mean 0.46±0.36 logMAR, median 0.3 logMAR vs. 0.32±0.31 logMAR, median 0.24 logMAR, p=0.020) ; in strabismic amblyopes (mean 0.52±0.32 logMAR, median 0.46 logMAR vs 0.34±0.27 logMAR, median 0.25 logMAR, p=<0.001) and in anisometropic amblyopes (mean 0.6±0.31 logMAR, median 0.57 logMAR vs. mean 0.36±0.25 logMAR, median 0.28 logMAR, p=<0.001).
In this small cohort of patients, grating acuity has underestimated amblyopia magnitude when compared to the clinical gold standard optotype acuity. These results confirm previous findings that amblyopia causes deeper functional deficits in more complex visual tasks such as optotype acuity.
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