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 handi cap were included and grouped into five subscales. The 76-item 'Impact of V ision Impairment' was administered to 95 people who were vision impaired. C ontent validity was established by consultation with professionals and with people with impaired vision. Forty-six items remained after the eliminatio n of those found to be irrelevant and others with inter-item correlation co efficients of greater than or equal to 0.7. Univariate and multivariate ana lyses revealed an association between visual acuity and type and degree of handicap on subscales, except emotional reaction to vision loss, which is r elated to cause of vision impairment. The instrument is responsive to the l evel of vision loss and discriminates the different performances of people with different causes of vision loss.