Important areas of the central binocular visual field for daily functioning in the visually impaired

Purpose:  To determine the areas of the central binocular visual field which correspond best with self-reported vision related activity limitations (VRAL) in individuals with visual impairment using a clinically relevant and accessible technique. Methods:  One hundred participants with mixed visual impairment undertook binocular threshold visual field testing using a Humphrey 30-2 SITA Fast program. The Activity Inventory (AI) was administered to assess overall, mobility related and reading related self-reported VRAL as part of a face-to-face clinical interview. Different eccentricities of the binocular field (central 5, 5–10, and 10–30°) were compared to self-reported VRAL in bivariate analyses and further explored using multivariate analyses. Results:  All areas of the binocular visual field were significantly associated with self-reported VRAL in bivariate analyses, with greater field loss associated with increased VRAL (p < 0.001). Multivariate analyses identified that function of the central 5–10° best predicted overall self-reported VRAL, and function of the central 5° (especially the right-hand-side) and the central 10–30° (especially 10–20°) best predicted self-reported VRAL in reading and mobility tasks, respectively. Conclusions:  The results highlight the association between central binocular visual fields and self-reported VRAL in people with visual impairment. Central binocular fields can be measured using a widely available threshold test in order to understand the likely functional limitations of those with vision loss, particularly in mobility tasks. Self-reported VRAL can be estimated using the regression equations and graphs provided and difficulty levels in specific tasks can be determined.