Reliability and validity of the ocular surface disease index

Objective: To evaluate the validity and reliability of the Ocular Surface D isease Index (OSDI) questionnaire. Methods: Participants (109 patients with dry eye and 30 normal controls) co mpleted the OSDI, the National Eye Institute Visual Functioning Questionnai re (NEI VFQ-25), the McMonnies Dry Eye Questionnaire, the Short Form-12 (SF -12) Health Status Questionnaire, and an ophthalmic examination including S chirmer tests, tear breakup time, and fluorescein and lissamine green stain ing. Results: Factor analysis identified 3 subscales of the OSDI: vision-related function, ocular symptoms, and environmental triggers. Reliability (measur ed by Cronbach alpha) ranged from good to excellent for the overall instrum ent and each subscale, and test-retest reliability was good to excellent. T he OSDI was valid, effectively discriminating between normal, mild to moder ate, and severe dry eye disease as defined by both physician's assessment a nd a composite disease severity score. The OSDI also correlated significant ly with the McMonnies questionnaire, the National Eye Institute Visual Func tioning Questionnaire, the physical component summary score of the Short Fo rm-12, patient perception of symptoms, and artificial tear usage. Conclusions: The OSDI is a valid and reliable instrument for measuring the severity of dry eye disease, and it possesses the necessary psychometric pr operties to be used as an end point in clinical trials.