title: Assessing visual acuity across five disease types: ETDRS charts are faster with clinical outcome comparable to Landolt Cs.
abstract: BACKGROUND
  Given the diversity of visual acuity tests being employed across the world, we compared two frequently applied tests: ETDRS charts and an eight-orientation projected Landolt C test in accordance with ISO 8596 and DIN 58220 part 3. The goals of the investigation were to determine (i) test agreement and (ii) test-retest reliability, to assess (iii) test durations, and (iv) the acceptance of the tests by the examinees as well as the subjects' coping with the tests as rated by the examiner.
  
  
  METHODS
  Seventy-five adult subjects with a visual acuity of ≥0.2 (4/20) were included in one of the following groups: normal, media opacity, maculopathy, optic neuropathy, (post)chiasmal lesion, or amblyopia. Visual acuity testing was carried out monocularly, in balanced randomized order and in two runs for each test on the same eye, applying forced choice.
  
  
  RESULTS
  Agreement: Within each group, all tests were performed similarly, within ±0.048 logMAR. Reliability: Across all subject groups, with a probability of 95 %, test-retest differences were <0.18 logMAR for both ETDRS and Landolt tests.
  
  
  METHODS
  The Landolt test lasted, on average, 1.8 times longer than ETDRS charts (p < 0.001). Acceptance: Examinees preferred the ETDRS test (p < 0.001), the examiner on average had no preference.
  
  
  CONCLUSIONS
  The Landolt C test and the ETDRS test yielded comparable results in visual acuity and test-retest reliability in all disease groups. The ETDRS test was usually faster and more accepted by both examiners and examinees than the Landolt test.
authors.affiliation: Centre for Ophthalmology, University Eye Hospital, Schleichstraße 12, 72076, Tuebingen, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Koenig
authors.forename: Felix
authors.initials: F
authors.lastname: Tonagel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schiefer
authors.forename: Michael
authors.initials: M
authors.lastname: Bach
authors.forename: Sven P
authors.initials: SP
authors.lastname: Heinrich
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000550:Amblyopia / Q000503:physiopathology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D015203:Reproducibility of Results; D012164:Retinal Diseases / Q000503:physiopathology*; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult