OBJECTIVES: The EAPIQ was developed based on a pilot study conducted in the US and focus groups with eye allergy sufferers in Europe. The purpose of this study is to present the results of the EAPIQ's construct validity and reliability testing. METHODS: A total of 146 patients from 2 allergy clinics completed the EAPIQ twice over a two-week period during the fall and winter allergy seasons, along with concurrent measures of health status, work productivity, and utility. Construct validity, reliability and known groups validity were assessed. RESULTS: Results from the validation study suggested the deletion of 14 items that required patients to complete the percentage of time they were troubled by something (daily activity limitations/emotional troubles). These questions yielded a significant amount of missing or inconsistent data (50%). The resulting factor analysis suggested four domains: symptoms, daily activity limitations, emotional well-being, and treatment satisfaction. The relative merits of assessing symptom-bother separately from symptom-frequency were also assessed. Results indicated that the two scales were highly correlated (>0.9) and known groups validity testing suggested the superior discriminative ability of the symptom frequency measure (F = 44.63 vs 39.63). However, when symptom bother and frequency items were summated discriminative validity was superior (F = 45.29). As a result, it was decided to sum the symptom bother and frequency items. All items met the tests for item convergent validity (item-scale correlation > = 0.4). The success rate for item discriminant validity testing was 97% (item-scale correlation greater with own scale than with any other). Internal consistency reliability criterion (> = 0.7) were met for all scales (range 0.89-0.93). Ongoing work will assess the test-retest reliability and known groups' validity of the EAPIQ. CONCLUSIONS: Asking patients to write in responses can lead to inconsistent responses or missing data. With the deletion of those items, the EAPIQ was found to have satisfactory construct validity and reliability.