Relation between Self-Perceived Status of Visual Functioning (VF-14) and Indices of Functional Vision Derived from Visual Acuity Measurements

Abstract

Many sources have advocated the use of indices of functional vision to measure the severity of visual impairment and their consequences on the quality of life. Different methods have been proposed. Traditional methods rely on monocular or binocular visual acuity (VA). The severity scale of impairment of the World Health Organisation1 is based on the best-eye VA and/or on the visual field. Other methods use various combinations of monocular VA (expressed as percentages) to calculate "weighted binocular scores", as proposed by the American Medical Association2 or Colenbrander3. A more recent approach, relies on the self-perceived status of visual functioning as measured by vision-related questionnaires. A variety of instruments have been devised to assess vision-targeted functional performance associated with visual impairment in subjects with cataract4-7. Of these, the Visual Functioning Index (VF-14) is one of the most widely used. The reliability, validity as well as the responsive ness of the VF-14 has been well documented in the case of cataract surgery7-10. In addition, this questionnaire has recently been validated for the evaluation of corneal and other ocular diseases11, 12