title: PROSPECTIVE EVALUATION OF VISUAL ACUITY AGREEMENT BETWEEN STANDARD EARLY TREATMENT DIABETIC RETINOPATHY STUDY CHART AND A HANDHELD EQUIVALENT IN EYES WITH RETINAL PATHOLOGY.
abstract: OBJECTIVE
  To evaluate the visual acuity agreement between a standard back-illuminated Early Treatment Diabetic Retinopathy Study (ETDRS) chart and a handheld internally illuminated ETDRS chart.
  
  
  METHODS
  Two-center prospective study. Seventy patients (134 eyes) with retinal pathology were enrolled between October 2012 and August 2013. Visual acuity was measured using both the ETDRS chart and the handheld device by masked independent examiners after best protocol refraction. Examination was performed in the same room under identical illumination and testing conditions.
  
  
  RESULTS
  The mean number of letters seen was 63.0 (standard deviation: 19.8 letters) and 61.2 letters (standard deviation: 19.1 letters) for the ETDRS chart and handheld device, respectively. Mean difference per eye between the ETDRS and handheld device was 1.8 letters. A correlation coefficient (r) of 0.95 demonstrated a positive linear correlation between ETDRS chart and handheld device measured acuities. Intraclass correlation coefficient was performed to assess the reproducibility of the measurements made by different observers measuring the same quantity and was calculated to be 0.95 (95% confidence interval: 0.93-0.96). Agreement was independent of retinal disease.
  
  
  CONCLUSIONS
  The strong correlation between measured visual acuity using the ETDRS and handheld equivalent suggests that they may be used interchangeably, with accurate measurements. Potential benefits of this device include convenience and portability, as well as the ability to assess ETDRS visual acuity without a dedicated testing lane.
authors.affiliation: *Retina Service, Wills Eye Hospital, Philadelphia, Pennsylvania; and †Retina-Vitreous Associates Medical Group, Los Angeles, California.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Rahimy
authors.forename: Sahitya
authors.initials: S
authors.lastname: Reddy
authors.forename: Francis Char
authors.initials: FC
authors.lastname: DeCroos
authors.forename: M Ali
authors.initials: MA
authors.lastname: Khan
authors.forename: David S
authors.initials: DS
authors.lastname: Boyer
authors.forename: Omesh P
authors.initials: OP
authors.lastname: Gupta
authors.forename: Carl D
authors.initials: CD
authors.lastname: Regillo
authors.forename: Julia A
authors.initials: JA
authors.lastname: Haller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D034201:Computers, Handheld; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012160:Retina / Q000503:physiopathology; D012164:Retinal Diseases / Q000503:physiopathology*; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult