Thai version of the dry eye-related quality-of-life score questionnaire: preliminary assessment for psychometric properties

Abstract

Background: This study aimed to develop a Thai version of the Dry Eye–Related Quality-of-Life Score (DEQS-Th) questionnaire and evaluate its validity, reliability, and feasibility among Thai participants. Methods: The DEQS-Th, a 15-item self-report measuring dry eye and its impact on quality of life (QOL) was developed based on the DEQS. The questionnaire was divided into two subscales: Bothersome Ocular Symptoms (six questions), and Impact on Daily Life (nine questions). It employed a 5-point Likert scale, addressing on both the frequency and the degree of symptoms. Backward and forward and cultural adaptation process translation methods were employed. Thirty healthy participants were enrolled to evaluate the feasibility of the DEQS-Th in terms of difficulty and convenience. Reliability was assessed using internal consistency determined by Cronbach’s alpha, with values > 0.7 considered acceptable. Convergent validity was determined by the correlation between DEQS-Th and overall health status. Confirmatory factor analysis was conducted for its factor structure. Results: The participants’ mean age was 38.6 ± 12.9 years, and 23 (76.7%) were females. The mean time to complete the questionnaire was 9.3 ± 2.7 min. The Cronbach’s alpha of the ocular symptoms subscale, impact on QOL subscale, and summary score on frequency and degree were 0.80 and 0.70, 0.89 and 0.89, and 0.90 and 0.89, respectively. The overall health status significantly correlated with the summary score (r = 0.564, p =.001), subscale ocular symptoms (r = 0.594, p =.001), and impact on QOL scores (r = 0.626, p <.001) of the DEQS-Th, respectively. A one-factor model fitted the data the best for both the ocular symptoms subscale (CFI = 1.000, TLI = 1.000, RMSEA = 0.000) and the impact on QOL subscale (CFI = 0.998, TLI = 0.997, RMSEA = 0.053). Conclusion: When tested among normal participants, the DEQS-Th is a valid and reliable measurement for dry eye symptoms and impact on QOL.