title: Enhancing the cross-cultural adaptation and validation process: linguistic and psychometric testing of the Brazilian-Portuguese version of a self-report measure for dry eye.
abstract: OBJECTIVE
  To provide a reliable, validated, and culturally adapted instrument that may be used in monitoring dry eye in Brazilian patients and to discuss the strategies for the enhancement of the cross-cultural adaptation and validation process of a self-report measure for dry eye.
  
  
  METHODS
  The cross-cultural adaptation process (CCAP) of the original Ocular Surface Disease Index (OSDI) into Brazilian-Portuguese was conducted using a 9-step guideline. The synthesis of translations was tested twice, for face and content validity, by different subjects (focus groups and cognitive interviews). The expert committee contributed on several steps, and back translations were based on the final rather than the prefinal version. For validation, the adapted version was applied in a prospective longitudinal study to 101 patients from the Dry Eye Clinic at the General Hospital of the University of São Paulo, Brazil. Simultaneously to the OSDI, patients answered the short form-36 health survey (SF-36) and the 25-item visual function questionnaire (VFQ-25) and underwent clinical evaluation. Internal consistency, test-retest reliability, and measure validity were assessed.
  
  
  RESULTS
  Cronbach's alpha value of the cross-culturally adapted Brazilian-Portuguese version of the OSDI was 0.905, and the intraclass correlation coefficient was 0.801. There was a statistically significant difference between OSDI scores in patients with dry eye (41.15 ± 27.40) and without dry eye (17.88 ± 17.09). There was a negative association between OSDI and VFQ-25 total score (P < 0.01) and between the OSDI and five SF-36 domains. OSDI scores correlated positively with lissamine green and fluorescein staining scores (P < 0.001) and negatively with Schirmer test I and tear break-up time values (P < 0.001).
  
  
  CONCLUSIONS
  Although most of the reviewed guidelines on CCAP involve well-defined steps (translation, synthesis/reconciliation, back translation, expert committee review, pretesting), the proposed methodological steps have not been applied in a uniform way. The translation and adaptation process requires skill, knowledge, experience, and a considerable investment of time to maximize the attainment of semantic, idiomatic, experiential, and conceptual equivalence between the source and target questionnaires. A well-established guideline resulted in a culturally adapted Brazilian-Portuguese version of the OSDI, tested and validated on a sample of Brazilian population, and proved to be a valid and reliable instrument for assessing patients with dry eye syndrome in Brazil.
authors.affiliation: Department of Ophthalmology, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255 - São Paulo - SP, 05403-000, Brazil. Electronic address: santo.ruth@gmail.com.
authors.forename: Ruth Miyuki
authors.initials: RM
authors.lastname: Santo
authors.affiliation: Department of Radiology, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255 - São Paulo - SP, 05403-000, Brazil.
authors.forename: Felipe
authors.initials: F
authors.lastname: Ribeiro-Ferreira
authors.affiliation: Department of Ophthalmology, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255 - São Paulo - SP, 05403-000, Brazil.
authors.forename: Milton Ruiz
authors.initials: MR
authors.lastname: Alves
authors.affiliation: Université de Lorraine, Université Paris Descartes, APEMAC EA 4360, Faculté de Médecine, 9 avenue de la Forêt de Haye, 54505 Vandoeuvre-lès-Nancy, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Epstein
authors.affiliation: Department of Ophthalmology, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255 - São Paulo - SP, 05403-000, Brazil.
authors.forename: Priscila
authors.initials: P
authors.lastname: Novaes
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil; D003431:Cross-Cultural Comparison; D015352:Dry Eye Syndromes / Q000175:diagnosis*; D005260:Female; D006306:Health Surveys; D006801:Humans; D007802:Language; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011174:Portugal; D011446:Prospective Studies; D011594:Psychometrics / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D057566:Self Report; D011795:Surveys and Questionnaires; D014177:Translations; D055815:Young Adult
keywords: Cross-cultural adaptation; Dry eye; Ocular Surface Disease Index; Questionnaires; Self-report measure; Translation; Validation studies