Can listening provide a useful clinical estimate of low vision reading parameters?

Abstract

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The purpose of this study was to determine whether a clinician can assess critical print size (CPS) and/or reading fluency by listening to a visually impaired patient reading aloud across a range of print sizes on an MNREAD chart, rather than needing to plot and analyse reading speed data as a function of print size. Fifty-six low vision participants were audio-recorded reading an MNREAD chart under standard conditions. Two experienced raters listened to the recordings and made judgments of the CPS (logMAR), and of the level of reading fluency achieved at large print sizes on a 4-point rating scale. Reading times were plotted as a function of print size to determine the CPS as the smallest print size that supported the participant's maximum reading speed (MRS) by inspection, and the MRS as the mean reading speed across print sizes including, and larger than, the CPS. Listened CPS judgments made for each rater were slightly larger than the CPS values obtained by inspection (mean differences 0.04logMAR (p=0.06), 0.08logMAR (p<0.01); limits of agreement (LoA) ±0.28logMAR, ±0.39logMAR, respectively). CPS judgments were consistent both between raters (mean difference 0.04logMAR [p=0.18]; LoA ±0.42logMAR) and between two judgments made by each rater (mean differences 0.00logMAR (p=1.0), 0.03logMAR (p<0.05); LoA ±0.23logMAR, ±0.17logMAR). Reading fluency could be categorised as 'functional' (MRS>80wpm) or 'non-functional' (MRS<80wpm) with a sensitivity of 88%-90% and a specificity of 100%. Experienced raters listening to a patient reading an MNREAD chart can determine a clinically useful estimate of critical print size and can discriminate maximum reading speeds that are above and below that likely to provide sustained reading ability. Listening to a patient reading an MNREAD chart is an option for the low vision clinician's armoury of assessments.