Background: To develop the Chinese version of quality of life scale for dry eye patients based on the Impact of Dry Eye on Everyday Life (IDEEL) questionnaire and to assess the reliability and validity of the developed scale.
Methods: The original IDEEL was adapted cross-culturally to Chinese language and further developed following standard procedures. A total of 100 Chinese patients diagnosed with dry eye syndrome were included to investigate the psychometric properties of the Chinese version of scale. Psychometric tests included internal consistency (Cronbach's ɑ coefficients), construct validity (exploratory factor analysis), and known-groups validity (the analysis of variance).
Results: The Chinese version of Dry Eye Related Quality of Life (CDERQOL) Scale contains 45 items classified into 5 domains. Good to excellent internal consistency reliability was demonstrated for all 5 domains (Cronbach's ɑ coefficients range from 0.716 to 0.913). Construct validity assessment indicated a consistent factorial structure of the CDERQOL scale with hypothesized construct, with the exception of "Dry Eye Symptom-Bother" domain. All domain scores were detected with significant difference across three severity groups of dry eye patients (P < 0.05) except for "Satisfaction with Treatment" domain, indicating good known-groups validity.
Conclusions: The results indicated that the CDERQOL scale is a reliable and valid instrument for patients with dry eye syndrome among Chinese population, and could be used as a supplementary diagnostic and treatment-effectiveness measure.
Keywords: Dry eye syndrome; Health-related quality of life; Reliability; Scale; Validity.