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

Background/Objectives: This study aimed to translate and validate the Lithuanian version of the 5-Item Dry Eye Questionnaire (DEQ-5). 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.