title: An investigation into the validity of self-reported classification of refractive error.
abstract: OBJECTIVE
  To assess the validity of questionnaire use in the self-identification of refractive status.
  
  
  METHODS
  Two hundred and forty adults (21-60 years of age) presenting for a routine eye examination at various optometric practices in Northern Ireland were asked to complete one of two questionnaires. Both questionnaires used identical questions to ascertain age, gender, current spectacle use, age of first spectacle use and level of education. For the identification of refractive status, Questionnaire 1 used layman's terminology whilst Questionnaire 2 combined optometric terminology with descriptive explanations. Current refractive status was identified by the examining optometrist who did not see the completed questionnaire. The spherical equivalent refractive error of the non-cycloplegic subjective refraction was used to categorise myopia as <0D and hyperopia as ≥+1.00D. Astigmatism was defined according to two different criteria: ≥0.50DC and ≥1.00DC.
  
  
  RESULTS
  Questionnaire 1 had a sensitivity of 0.63 and a specificity of 0.90 for identifying myopia; a sensitivity of 0.58 and a specificity of 0.71 for identifying hyperopia; a sensitivity of 0.12 and a specificity of 0.98 for identifying astigmatism ≥0.50DC and a sensitivity of 0.19 and a specificity of 0.95 for identifying astigmatism ≥1.00DC. Questionnaire 2 had a sensitivity of 0.83 and a specificity of 0.93 for identifying myopia; a sensitivity of 0.45 and a specificity of 0.86 for identifying hyperopia; a sensitivity of 0.32 and a specificity of 0.88 for identifying astigmatism ≥0.50DC and a sensitivity of 0.50 and a specificity of 0.84 for identifying astigmatism ≥1.00DC. For both questionnaires, altering a positive self-identification of myopia to include only those who had worn spectacles prior to age 30 reduced the sensitivity and increased the specificity slightly.
  
  
  CONCLUSIONS
  Questionnaires are a valid tool in self-identification of myopic refractive status. However, they are not an effective way of identifying hyperopia and astigmatism and objective or subjective refraction remains the most appropriate method of identifying such individuals.
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, UK.
authors.forename: Karen M M
authors.initials: KM
authors.lastname: Breslin
authors.forename: Lisa
authors.initials: L
authors.lastname: O'Donoghue
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Saunders
mesh_terms: D000328:Adult; D059026:Diagnostic Self Evaluation; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009660:Northern Ireland; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult
keywords: astigmatism; hyperopia; myopia; questionnaire; sensitivity; specificity