Validation of the daily living tasks dependent on vision (DLTV) questionnaire in a U.S. population with age-related macular degeneration

Purpose: The Daily Living Tasks Dependent on Vision questionnaire (DLTV) has been used to assess functional impairment among patients with age-related macular degeneration (AMD). This study evaluated the psychometric properties of the DLTV using patient-reported rates of use of services and devices in an outpatient population. Methods: The DLTV was included in a survey mailed to members of an AMD advocacy organization. Included in the survey were questions about demographic and clinical characteristics as well as questions about use of low vision aids and care-giving. Respondents provided informed consent. Data were analyzed in SAS. Results: Four respondents of 803 did not complete the DLTV; missing data were uncommon. Most (56%) respondents were male; the mean age was 73 years. Internal consistency reliability of the DLTV was 0.9699. Construct validity was demonstrated with moderate to high correlations between the DLTV and use of services and devices. The DLTV demonstrated discriminant validity and could distinguish between respondents with different levels of impairment, i.e., those who reported regular care-giving compared to those without regular care-giving. Conclusions: In this outpatient population, the DLTV demonstrated reliability and validity. This analysis complements existing research and supports the use of the DLTV in AMD patients.