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Rachel Mercer, Tomohiko Yamada, David Leske, Pamela Moke, Jonathan Holmes; Comparison of HOTV with Lea Optotypes Using the Amblyopia Treatment Study Protocol in 2- to 4-Year-Old Children. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3984.
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Obtaining optotype visual acuity (VA) in 2- to 4-year-old children can be challenging. The Pediatric Eye Disease Investigator Group (PEDIG) developed the Amblyopia Treatment Study (ATS) visual acuity protocol to standardize presentation of HOTV optotypes for children aged three years and older. Alternative optotypes for children are Lea symbols, which may allow testing of even younger children. Previous studies have focused on comparing testability of HOTV and Lea Symbols as screening tools, rather than for determining VA thresholds. We compared testability and VA thresholds between HOTV and Lea optotypes using the ATS-VA protocol in 2-to 4-year-old children.
Sixty children aged 2 to 4 years were prospectively enrolled from outpatient pediatric ophthalmology/optometry clinics. VA was measured using two optotype sets, HOTV and Lea, each presented using the standardized ATS-VA protocol (isolated and crowded) on the Electronic Visual Acuity Tester, using a matching card for each optotype set. Testing order was randomized. Testability (defined as completion of the full presentation protocol for both eyes) was compared with Fisher’s Exact tests. VA thresholds (defined as the smallest optotype level passed with 3 of 3 or 3 of 4 correct responses) were compared using generalized estimating equations. Intraclass correlation coefficients (ICC) were also calculated to assess agreement of thresholds between tests.
Testability was high for both HOTV and Lea in 4-year olds (91% on HOTV vs 91% on Lea, p=1.0) and for 3-year olds (70% vs 80%, p= 0.7). Testability was low for 2-year olds (0% vs 6%, p=1.0). For 66 eyes of 33 children testable with both tests, VA thresholds were almost identical (HOTV mean 0.215 vs Lea mean 0.201 LogMar, difference = 0.014 LogMar, 95% confidence interval (CI), -0.018, 0.049). Agreement of thresholds was excellent for both right eyes (ICC=0.91, 95% CI 0.84, 0.96) and left eyes (ICC=0.91, 95% CI=0.84, 0.96).
Using the ATS VA protocol and matching cards, which standardizes the presentation of isolated crowded optotypes, both HOTV and Lea had excellent testability in 3- and 4-year olds, but poor testability in 2-year olds. VA thresholds were similar between HOTV and Lea using the ATS VA protocol. Using either HOTV or Lea optotype is very reasonable for testing VA thresholds in 3- to 4-year-old children.
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