title: Screening for myopia and refractive errors using LogMAR visual acuity by optometrists and a simplified visual acuity chart by nurses.
abstract: OBJECTIVE
  To compare the sensitivity and specificity of a widespread method of screening for refractive errors in Singapore schoolchildren using a simplified acuity screening chart with a more rigorous method using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. A secondary aim is to estimate the best cutoff values for the detection of refractive errors using these two methods.
  
  
  METHODS
  This is a population-based study, involving 1779 schoolchildren from three schools in Singapore. Logarithm of the minimum angle of resolution (logMAR) visual acuity was recorded using a modified Bailey-Lovie chart by trained optometrists, and visual acuity measurement was also undertaken using a simplified 7-line visual acuity screening chart by school health nurses. The main outcome measures were the receiver-operating characteristics (ROC's) of logMAR and the simplified screening visual acuity to detect myopia or any refractive errors. The difference between measurements, simplified screening visual acuity--logMAR visual acuity, was calculated.
  
  
  RESULTS
  The optimal threshold using the simplified screening visual acuity chart for the detection of myopia or any refractive error was 6/12 or worse. Using logMAR visual acuity, the most efficient threshold for the detection of myopia was 0.26, but this was 0.18 for the detection of any refractive error. The area under the ROC curves was significantly greater in the case of the logMAR visual acuity measurement compared with the simplified screening visual acuity measurement for the detection of myopia or any refractive errors. The 95% limits of agreement for the two methods (simplified screening--logMAR acuity) was -0.219 to +0.339.
  
  
  CONCLUSIONS
  Bearing in mind that the visual acuity measurements were performed by two different groups of professionals, visual acuity screening using the ETDRS method appears to be more accurate than the simplified charts for the detection of myopia or any refractive errors in children.
authors.affiliation: Singapore National Eye Center, Singapore. Louistong@hotmail.com
authors.forename: Louis
authors.initials: L
authors.lastname: Tong
authors.forename: Seang-Mei
authors.initials: SM
authors.lastname: Saw
authors.forename: Edwin Shih-Yen
authors.initials: ES
authors.lastname: Chan
authors.forename: Mabel
authors.initials: M
authors.lastname: Yap
authors.forename: Heow-Yong
authors.initials: HY
authors.lastname: Lee
authors.forename: Yoke-Pin
authors.initials: YP
authors.lastname: Kwang
authors.forename: Donald
authors.initials: D
authors.lastname: Tan
mesh_terms: D002648:Child; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis*; D009726:Nurses; D009907:Optometry / Q000379:methods*; D012372:ROC Curve; D012030:Refractive Errors / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D015351:Vision Screening / Q000379:methods; D014787:Vision Tests / Q000295:instrumentation; D014792:Visual Acuity