Current licensing authority standards for peripheral visual field and safe on-road senior aged automobile driving performance

Background: The current licensing authority's (Austroads) visual field standards are met when a person demonstrates an intact visual field extending horizontally at least 120 degrees within 10 degrees above and below the horizontal midline. A person cannot be licensed unconditionally if they have a hemianopia, quadrantanopia or any significant visual field loss (scotoma) that is likely to impede driving performance. Despite fairly rigorous implementation of these vision standards by licensing authorities, there is little scientific evidence available to demonstrate that a driver will or will not be safe on road depending on the extent of their visual field. Methods: This study was developed to examine if the current licensing authority vision standards predict safe on-road driver performance in a cohort of 100 senior drivers. The study consisted of four stages in which participants underwent on-road assessment by a multidisciplinary team including a driving instructor, orthoptist and occupational therapist; off-road occupational therapy cognitive skills assessment using the Visual Recognition Slide Test (VRST-USyd); off-road orthoptic assessment including history, visual acuity and visual fields; and feedback from the team regarding the participant's visual and driving status. Visual fields were assessed using both the Goldmann and Esterman tests. Correlations were calculated to determine the relationship between visual field results and on-road driving performance. Results: Generally it was found that visual field test results did not predict driving performance accurately for both participants with and without visual field loss. Conclusion: The results bring into question the current Austroads visual field standards for safe driving.