The visual acuity charts developed for the Early Treatment Diabetic Retinopathy Study (ETDRS) offered a rigorous chart design and test protocol, that has been widely adopted in basic and clinical vision research. Today, the ETDRS format forms the gold standard for measuring visual acuity.

A limitation of the original ETDRS charts is that they do not allow for European-wide implementation, since they contain letters from the Latin (Roman) alphabet, which are not readable by all European citizens.

To facilitate reliable visual acuity screening for clinical trials and exchange of patient data between doctors, clinics and researchers throughout Europe and beyond, researchers at the University of Crete (Dr. Sotiris Plainis, Prof. Miltiadis Tsilimbaris and Prof. Ioannis Pallikaris), have developed modified ETDRS charts that contain only capital letters that are common to all three European alphabets (Latin, Greek, Cyrillic), and are thus recognizable for a much wider population.

The new charts have been validated against the original ETDRS charts in Greece, Bulgaria and Belgium (see relevant article). They were found to produce comparable visual acuity scores with a test-retest repeatability of about 0.10 logMAR (see ARVO poster). Charts for measuring both distance and near/intermediate visual acuity are available.