Validation of a modified ETDRS chart for European-wide use in populations that use the Cyrillic, Latin or Greek alphabet
Plainis S., Moschandreas J., Giannakopoulou T., Vitanova V., Nikolitsa P., Rozema JJ., Tassignon MJ., Tsilimbaris MK., Pallikaris IG.
Purpose: To validate a modified ETDRS visual acuity (VA) chart developed for European-wide use, in populations that use the Cyrillic, Latin or Greek alphabet. Methods: The charts were validated in three groups: 310 school children in Bulgaria (mean age 13 ± 1 years), 227 school children in Greece (mean age 14 ± 1 years) and 85 patients with no ocular pathology in Belgium (mean age 26 ± 5 years). VA was assessed with the habitual refractive correction, using the standard ETDRS charts and the modified European-wide charts. The intra-class correlation coefficient (ICC) was used to assess the test-retest reliability of the European-wide chart. The Bland-Altman comparison method was used to assess agreement between the two different versions of the new chart, as well as to compare these to the standard ETDRS-charts. Limits of agreement were calculated for differences in VA scores (test-retest variability (TRV)) between measurement sessions for the European-wide charts. Results: The TRV of the European-wide charts was found to be ±0.10 logMAR, corresponding to 5 ETDRS letters, for both chart 1 and chart 2. The ICC was estimated to be 0.968 for the RE and 0.961 for the LE. The European-wide charts generated on average slightly higher logMAR scores compared to the standard ETDRS charts in all three groups. Conclusions: The "European-wide" charts appear to be a valid alternative to the standard ETDRS acuity charts, offering the advantage of containing letters readable by all European citizens. © 2012 Spanish General Council of Optometry.