Towards Worldwide Comparability of Visual Acuity Assessment A Pilot Study Comparing ETDRS Visual Acuity Charts, Projected Landolt Charts and the Freiburg Visual Acuity Test (FrACT) With a View to Developing a Mathematical Transformation Routine Between the Results From These Three Tests

Assessment of distant visual acuity is the most frequently used procedure for estimation of visual performance. However, there exist a vast number of markedly differing visual acuity tests worldwide; furthermore there are differing report formats to express acuity. This variety may critically interfere with standardization and comparability of this basic visual test method.

Purpose of this study is to investigate the agreement, the test-retest reliability of three established and widely used visual acuity tests, i.e., the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity charts, a conventional projected distant visual acuity test according to DIN 58220 part 3, and the Freiburg visual acuity test (FrACT), to develop a mathematical transformation routine between the results from these three tests, to assess the examinees´ and examiners´ acceptance and to compare the test durations.