Abstract
Abstract: :
Purpose: To develop a reliable and valid questionnaire (L V Prasad-Functional Vision Questionnaire, LVP-FVQ) to assess self-reported functional vision problems of visually impaired school children. Methods: A draft LVP-FVQ, consisting of 19 items was administered verbally to 78 visually impaired Indian school children aged 8-18 years. Each item was rated on a 5-point Likert scale. Test-retest reliability (intraclass coefficient) and internal consistency reliability (Cronbach's alpha) were assessed. Construct validation included consideration of the content validity, comparison with WHO categories of vision loss, and concurrent validity by comparing LVP-FVQ scores with clinical measures of vision. In the final LVP-FVQ, subjects also assessed their level of vision compared to friends (global rating of vision). Results: After item reduction, the final LVP-FVQ consisted of 4 domains with 13 items related to day-day activities of school children. The mean total LVP-FVQ score of 13 items was 17.02 (SD 11.68). Using factor analysis, the most frequently reported problems were grouped into 4 factors - visually demanding high contrast tasks, moderately visually difficult low contrast tasks, self-care and play activities - that accounted for 66.2% of the variability in the subjects' questionnaire responses. Test-retest reliability was 0.76 to 0.92 for the 4 domains and internal consistency was high (0.83). Item-total correlations ranged from 0.25-0.79 indicating good homogeneity. Construct validity was demonstrated by a significant relationship between responses to the global rating of vision and subjects' vision loss as per WHO criteria (p=0.012). Concurrent validity was demonstrated by a strong correlation between binocular distance visual acuity and the total score of distance vision items (p<0.001). From multiple linear regression analysis, the responses to 2 items, copying from the blackboard and reading at arm's length, were the best predictors of distance and near visual acuities. Conclusion: The LVP-FVQ shows promising results as a reliable, valid, and simple questionnaire to assess problems with functional vision in visually impaired children in developing countries such as India.
Keywords: 459 low vision • 619 vision and action • 359 clinical research methodology