Recognition acuity in children measured using The Auckland Optotypes

Abstract

Purpose: Sloan letters displayed by the Electronic Visual Acuity (EVA) system are the gold standard for recognition acuity measurement in research settings. However, letters are not always appropriate for children. The Auckland Optotypes (TAO) are a new, open-access set of 10 pictograms available in regular and vanishing formats. We sought to assess feasibility of using both formats of TAO for measuring visual acuity (VA) in children using a Bayesian adaptive staircase, in a community setting. Methods: We tested 121 children (5-12 years old) with both formats of TAO, a handheld flipchart vision screener (Parr vision test), as well as the gold standard EVA. We measured feasibility of the three comparison tests in three ways. First, using limits of agreement (LoA) with EVA, second, calculating area under the receiver operating characteristic curve (AUC), and finally, investigating trial-bytrial responses. Results: Agreement between tests was within test-retest reliability of EVA measures (LoA TAOregular = AE0.14, LoA TAOvanishing = AE0.15, LoA Parr = AE0.16 logMAR). TAO tests were highly effective at identifying children with vision impairment (AUC TAOregular = 0.96, AUC TAOvanishing = 0.95), whereas Parr was less effective (AUC Parr = 0.82). In 5-6 year old children there was an enhanced advantage of TAO (AUC TAOregular = 0.97, AUC TAOvanishing = 0.98) over Parr (AUC Parr = 0.75). Although each child completed 16 trials, approximately 10 trials were sufficient to achieve excellent LoA, and six trials sufficient for accurate screening. Conclusion: Threshold VA assessment and vision screening are feasible using both vanishing and regular formats of TAO.

Preliminary clinical validation of a new picture–based visual acuity test in children with amblyopia: a comparison of The Auckland Optotypes and crowded logMAR letters

“…Good agreement was established between TAO and letter VA (Figure 2 a-c), indicating that TAO appears to be an equivalent measure to letter VA in children with amblyopia. The 95% LoA established in this study in the AE (±0.24 logMAR) and FE (±0.25 logMAR) were similar to, albeit slightly wider than, previously reported comparisons between TAO and logMAR letters in visually normal children (±0.20 logMAR) (7,8). The LoA observed in this study are also in line with those for well-established and widely used picture acuity charts.…”

“…Existing evidence suggests that VA obtained with TAO is comparable to that obtained with ETDRS in adults. Similarly, strong agreement has been found between TAO and Sloan letters as well as Lea symbols in visually normal children (6)(7)(8). Such agreement is promising and suggests that TAO could enhance the accuracy of VA assessment in pre-literate children and potentially fulfil the criteria for a picture optotype test suitable for use in clinical trials.…”

Identification of appropriate tools to gauge brain functions in a clinical setup of a developing country: A pilot study

“…The reason Visual Function (VF) was preferred over Visual Acuity (VA) despite both having the same overall score was that; AUC for visual fields falls between 0.9 and 1.0 17 and that for visual acuity is between 0.8 and 0.9. 16 Similarly, accuracy for VA is 70-89% 17,18 and that for VF falls between 90-100%. 19 The link with brain function is higher for VF than for VA.…”

Bearing fixing: A new computer algorithm method for subjective determination of astigmatism

“…This technique is likely to be inefficient, because it ignores the results of other trials. Just as adaptive and Bayesian methods 34,38,39 of psychophysics can improve other threshold measures by making efficient use of previous estimates, e.g., acuity measurement, it is possible that better psychophysical procedures could be developed for measuring refraction. Computers, with their ability to store and use information from all previous trials, may be better suited than human clinicians for this.…”

“…Such computer‐controlled methods are commonly used for clinical decision making 33 and controlling other clinical psychophysical procedures, e.g., visual acuity measurements for children 34 and automated perimetry 35–37 . They offer the ability to standardise testing between clinicians and allow trained assistants to perform the procedures.…”