Comparison of applicability of different visual acuity charts for pediatric outpatient visual tests.

PURPOSE: To evaluate the applicability of different visual acuity charts for outpatient pediatric visual tests.

METHODS: Fifty-three children (53 eyes) aged 4-8 years undergoing visual acuity tests as outpatients were randomly selected for this study. The best corrected visual acuity (BCVA) of the eye with better visual acuity was measured for each child using the digital LogMAR visual chart, the ETDRS visual chart, and a new standard logarithm visual chart; all measurements were repeated twice and the BCVA was recorded. Paired comparisons were made between the LogMAR visual acuity chart and ETDRS chart measurements or between the ETDRS chart and logarithm visual acuity chart measurements for statistical analysis of the differences in measurement of visual acuity. The results of different measurements by the same chart were compared to evaluate the consistency of the measurement results. Bland-Altman analysis was employed to evaluate the most suitable chart for outpatient measurement of visual acuity in children.

RESULTS: Bland-Altman analysis revealed that the mean visual acuity measured was (0.447 ± 0.017 LogMAR) by the digital LogMAR chart, (0.301 ± 0.024 LogMAR) by the standard logarithm visual acuity chart, and (0.309 ± 0.018 LogMAR) by the ETDRS visual acuity chart. The BCVA was significantly lower when measured by the LogMAR visual acuity chart than by the ETDRS chart (P < 0.01). The BCVA was slightly higher when measured by the logarithm visual acuity chart than by the ETDRS chart, but the difference was not statistically significant (P > 0.05). The Bland-Altman plot showed that the highest consistency was obtained with the digital LogMAR chart, with a difference between two repeated measurements of 0.068 LogMAR, compared to 0.090 and 0.072 LogMAR for the logarithm and ETDRS visual acuity charts, respectively.

CONCLUSION: All three types of visual acuity charts are applicable for outpatient measurement of pediatric visual acuity. The ETDRS and logarithm visual acuity charts have a higher consistency, but the LogMAR visual acuity chart shows better reproducibility. Consequently, it is difficult to identify and distinguish which acuity chart is most suitable for cooperative children.