Translation and Validation of the 5-Item Dry Eye Questionnaire into Lithuanian

Background and Objectives: This study aimed to translate and validate the Lithuanian version of the 5-Item Dry Eye Questionnaire (DEQ-5). Materials and Methods: The original English DEQ-5 was translated and adapted into Lithuanian according to guidlines. A total of 40 Lithuanian-speaking adults without diagnosed ocular or systemic disease completed the questionnaire twice, with a 2-3-day interval. Internal consistency was evaluated using Cronbach's alpha and corrected item-total correlations. Test-retest reliability was assessed using the intraclass correlation coefficient (ICC), and convergent validity was evaluated by correlating DEQ-5 scores with the Lithuanian version of the Ocular Surface Disease Index (OSDI). Results: The Lithuanian DEQ-5 demonstrated good internal consistency (Cronbach's α = 0.843). Corrected item-total correlations ranged from 0.160 to 0.829, with Item 3 showing the weakest correlation. Test-retest reliability was good (ICC (A, 1) = 0.868; 95% CI: 0.764-0.928; p < 0.001). Bland-Altman analysis showed a mean difference (bias) of 0.075 points, with 95% limits of agreement ranging from -4.73 to 4.88 points. DEQ-5 scores showed a strong positive correlation with OSDI scores (Spearman's ρ = 0.796; 95% CI: 0.55-0.92, p < 0.001), providing evidence of convergent validity in the OSDI subgroup. Conclusions: The Lithuanian version of the DEQ-5 demonstrated good internal consistency and test-retest reliability, while evidence of convergent validity was observed among participants who completed the OSDI.