The Turkish version of the 5-item Dry Eye Questionnaire (T-DEQ-5): Translation, validity, and reliability

To evaluate the reliability and validity of Turkish translation of the 5-item Dry Eye Questionnaire (T-DEQ-5) and to compare it with the Ocular Surface Disease Index (OSDI) questionnaire, tear break-up time (TBUT), corneal staining, and Schirmer test results.

The linguistic validation procedures adopted internationally, including forward translations, backward translation into English, examination of the translation quality, and a pilot test on 10 subjects, were employed. The translated and validated questionnaire was applied to 25 subjects two-time points (second time within three days) to evaluate the intra-test reliability. One hundred subjects were recruited for the study. They underwent an ophthalmic examination, including Schirmer tests, TBUT, and ocular surface staining (OSS) after completing OSDI questionnaire. Receiver operating characteristics (ROC) were assessed to determine sensitivity and specificity of the T-DEQ-5.

The mean age of subjects was 45.7 ± 16.2 years, with 65 % being female. Overall, the test-retest reliability was excellent with an intra-class correlation coefficient value of 0.95 (95 % CI 0.90-0.98, p < 0.001). The Cronbach's alpha reliability coefficient was 0.90, which demonstrated a strong level of internal consistency of the T-DEQ-5. Using ROC analysis to compare the results of the T-DEQ-5 with those of the OSDI, the area under the curve was found 0.95, with an optimal cut-off threshold of 6, resulting in 81 % sensitivity and 91 % specificity. Establishing the diagnosis based on a positive OSDI (≥13) and at least one positive sign (TBUT and/or OSS) yielded a sensitivity of 95 % and a specificity of 87 % at the cut-off threshold of 6.

The Turkish version of the DEQ-5 is a valid and reliable questionnaire and capable of differentiating patients with dry eye.