Abstract
Abstract: :
Purpose:Determine the number of dimensions of disability among low vision patients that are measured by the SF–36, SIP, and a visual function activity inventory. Methods: A visual function activity inventory was administered by telephone interview to 407 low vision patients. In addition, the SF–36 was administered to 200 of these patients and the SIP was administered to the other 207 patients. Rasch analysis was performed on each of 4 visual function domains (reading, mobility, visual motor, visual information), each of 4 SF–36 domains, and each of 12 SIP domains. Exploratory factor analyses were performed on the person measures for each domain for each of the two groups of patients. Results:Four factors were found to be necessary and sufficient to account for the intercorrelations among domains for each of the two groups (74% of the variability for the SF–36 and 80% for the SIP). Two of the factors were visual, one associated with visual resolution and the other associated with mobility, one factor is associated with physical limitations and one factor is associated with mood/psychological state. The results were the same for the two groups of patients. Conclusions:The results indicate that there are at least four dimensions of disability within the low vision patient population: visual resolution, mobility, physical limitations, and psychological state/mood. The results would indicate that systemic co–morbidities and psychological state do not confound estimates of vision disability based on patient responses to visual functioning questionnaires.
Keywords: quality of life • low vision • clinical (human) or epidemiologic studies: outcomes/complications