title: Catatrac: a novel red light-emitting diode device for screening cataracts in the developing world.
abstract: OBJECTIVE
  The purpose of this study was to critically evaluate the Catatrac device as a potential tool for rapid cataract screening in the developing world.
  
  
  METHODS
  Patients attending the day case unit at Gartnavel General Hospital for routine cataract surgery were recruited into the study, and divided into two groups: those with mild cataracts with LogMAR acuities <0.48, and those with advanced cataracts with LogMAR acuities ≥0.48. The subjects were examined without pharmacological dilation in a dimly lit room independently by two nurses. Each patient was then examined by an ophthalmologist with a slit lamp, after dilation. If present, cataracts were graded objectively according to the LOCS III classification system.
  
  
  RESULTS
  One hundred and twenty-two eyes of 73 patients were screened for the presence or absence of cataract using the Catatrac device. Thirty-nine eyes had mild cataracts, 43 eyes had advanced cataracts, and there were 40 control eyes with no cataracts. For detecting advanced cataracts, the two nurses using the Catatrac device had a specificity of 95.0%, a sensitivity between 86.0 and 93.0%, and κ values between 0.81 and 0.88 for agreement with slit lamp assessment. For detecting mild cataracts the two nurses using the Catatrac device again had a specificity of 95%, sensitivity of 71-84.6%, and κ values between 0.67 and 0.80 for agreement with slit lamp assessment. Interobserver agreement between the two nurses had a κ value of 0.61 for mild cataract and 0.74 for advanced cataract.
  
  
  CONCLUSIONS
  The Catatrac device has a high specificity, sensitivity, and interobserver agreement for advanced cataracts. Although having a slightly lower sensitivity for mild cataracts, the authors believe that this study has demonstrated that it may be a low cost and easy to use device for rapid screening of visually significant cataracts in the developing world.
authors.affiliation: Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, UK. mamun.rahman@nhs.net
authors.forename: M Q
authors.initials: MQ
authors.lastname: Rahman
authors.forename: A P
authors.initials: AP
authors.lastname: Rotchford
authors.forename: K
authors.initials: K
authors.lastname: Ramaesh
mesh_terms: D000368:Aged; D002386:Cataract / Q000175:diagnosis*; D003906:Developing Countries; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D054023:Lasers, Semiconductor; D008027:Light; D008297:Male; D008403:Mass Screening / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity