Description and measurement of handicap caused by vision impairment

To develop an instrument to describe and quantify handicap caused by vision impairment an item pool was derived from focus groups and from a review of vision-related quality-of-life questionnaires. Only items related to handicap were included and grouped into five subscales. The 76-item 'Impact of Vision Impairment' was administered to 95 people who were vision impaired. Content validity was established by consultation with professionals and with people with impaired vision. Forty-six items remained after the elimination of those found to be irrelevant and others with inter-item correlation coefficients of > or = 0.7. Univariate and multivariate analyses revealed an association between visual acuity and type and degree of handicap on subscales, except emotional reaction to vision loss, which is related to cause of vision impairment. The instrument is responsive to the level of vision loss and discriminates the different performances of people with different causes of vision loss.