Purpose: Dry eye is common in Asian populations, but there are limited validated instruments available to assess ocular symptoms within these populations. This study aimed to develop and assess the psychometric properties of a Chinese version of the ocular comfort index (OCI-C).
Methods: The OCI was translated and back translated by 32 bilingual volunteers and a preliminary OCI-C was produced for analysis; 165 bilingual volunteers completed both the OCI and the preliminary OCI-C. The item scores for preliminary OCI-C were compared with the OCI using Cronbach's α. Repeatability of the total score of OCI-C was evaluated in a subgroup of 20 participants after a week by calculating the coefficient of repeatability (CoR) and intraclass correlation coefficient (ICC) for the OCI-C score; 322 subjects, including 81 dry eye subjects, completed the OCI-C to verify the sensitivity in dry eye diagnosis. Rasch analysis was used to estimate interval measures from ordinal Likert score and assess psychometric property of item-fit, category function, targeting of items to subjects, and person separation reliability.
Results: Cronbach's α for all items was above 0.85. The CoR was ± 5.84 and the ICC was 0.96 (95% confidence interval 0.91-0.98). The total score of OCI-C was able to differentiate dry eye (40.0) with non-dry eye (30.2) (P < 0.0001). In the Rasch analysis model, the OCI-C showed robust psychometric properties for item-fit and category calibration: person-separation reliability: 2.47 and item reliability: 8.42.
Conclusions: The psychometric properties of the OCI-C are comparable with the OCI and the instrument is appropriate as a diagnostic tool and to determine the severity of dry eye in this population.
Keywords: Chinese population; Rasch analysis; dry eyes; questionnaire; symptoms.
Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.