A practical approach to measuring the visual field component of fitness to drive

Abstract

Abstract: : Purpose:To determine the level of agreement between merged bilateral monocular visual field tests (the Integrated Visual Field, IVF) and the binocular Esterman visual field test in classifying patients’ visual status for UK legal fitness to drive. To examine the link between these two tests and the Useful Field of View (UFOV), a test which is considered to be a surrogate for the visual capability for safe driving. Methods:Primary open–angle glaucoma patients with bilateral overlapping visual field defects were recruited prospectively in a clinic–based setting. Patients performed the bilateral monocular field tests (to generate the IVF), the Esterman test and the UFOV test on the same visit. Patients were classified as ‘pass or ‘fail’ by both the IVF and the Esterman test. UFOV risk scores were calculated for each patient. Results:Sixty–five patients were recruited. Substantial agreement was found between the IVF and the Esterman test in classifying patients as ‘pass’ or ‘fail’ (kappa = 0.69). No patients classified as ‘pass’ by the IVF were classified as ‘fail’ by the Esterman test. Eight patients who were classified as ‘pass’ by the Esterman test were classified as ‘fail’ by the IVF. None of these eight were in the UFOV ‘low risk’ or ‘no risk’ categories. The UFOV characteristics of these eight were significantly different from those of the 44 patients who were classified as ‘pass’ by both the IVF and the Esterman test, but were very similar to those of the 13 patients who were classified as ‘fail’ by both the IVF and the Esterman test. Conclusions:The Integrated Visual Field agrees well with the current method (the Esterman test) of classifying visual fields with regard to legal fitness to drive in the UK. It appears superior to the current method in identifying those with reduced fitness to drive as measured by the UFOV. The Integrated Visual Field could perform a valuable screening or diagnostic role in the assessment of glaucoma patients’ fitness to drive. Comparison of Esterman test with IVF 

Keywords: visual fields • perimetry • quality of life