Bright prospects for City's colour vision research
A pioneering study carried out by the Applied Vision Research Centre has the potential to revolutionise medical certification process for a large number of visually demanding occupational environments.
John Barbur, Professor of Optics and Visual Science (pictured), founded the Applied Vision Research Centre (AVRC) at City University London in 1987 and has since led research into fundamental mechanisms of vision and development of novel instrumentation for vision research. In 2003, a £1.55 million grant from the Wellcome Trust and additional support from the University helped create the Henry Wellcome Laboratories for Vision Science. The combination of unique expertise in the field of colour vision science and cutting-edge research facilities has brought AVRC international recognition.
AVRC research areas cover fundamental visual processes, ophthalmic and physiological optics, vision care and clinical practice, visual neuroscience and the development of specialised instrumentation with emphasis on clinical applications.
Colour vision in safety-critical occupational environments
One of the Centre's recent research projects has the potential to revolutionise medical certification processes for professions where good eyesight and colour vision are critical. Conventional tests screen for congenital red-green deficiency; however, these tests exhibit large variability and cannot be used to diagnose the class of deficiency or to quantify accurately the severity of colour loss. In some professions, such as air traffic control, extensive use of colour signals and displays also requires normal yellow-blue colour vision.
In the past, pilot, train driver and firefighter applicants often failed certification because of congenital colour deficiency, even when they were able to carry out visually-demanding, colour-related tasks with the same accuracy as subjects with normal colour vision. As part of studies on camouflage, the AVRC team discovered the existence of independent visual mechanisms for the processing of luminance contrast noise and colour signals. This investigation led to the development of the Colour Assessment and Diagnosis (CAD) test with funding from the UK Civil Aviation Authority (CAA) and US Federal Aviation Administration (FAA).
The CAD test identifies the class of colour vision deficiency and provides a far more accurate assessment of a person's colour vision. The test establishes with perfect specificity whether a person's red-green and yellow-blue colour vision falls within the normal range and quantifies the severity of any form of colour loss. Results showed that many people with minimal colour deficiency are able to perform visually-demanding, safety-critical tasks just as well as those with normal colour vision.
The adoption of the CAD test led to the introduction of new pass/fail limits for aviation that do not disadvantage applicants with congenital colour vision deficiency who can perform colour-critical tasks. Dr Sally Evans, Chief Medical Officer at the CAA, says:
Under the methods and limits used in this study, 35 per cent of colour deficient applicants would be eligible for medical certification as a pilot. The CAA and the FAA promote this research. The CAD test is likely to be incorporated into worldwide standards in the future.
Today the test is used routinely by worldwide aviation authorities, Transport for London and government departments as well as by research establishments, hospitals and optometrists.
Looking into the future
Professor Barbur has always recognised that the application of the CAD test may be extended beyond occupational health. In 2008 he was awarded the first City University London Annual Research Award for a project to study early vision changes in subjects with high risk of age-related macular degeneration. This work has evolved through a joint project with the Department of Ophthalmology, King's College London, and the first clinical trial of the CAD test has started in collaboration with Moorfields Abu Dhabi Hospital and the Imperial College Diabetes Unit. This will establish the usefulness of the test in early diagnosis of retinal disease with emphasis on related macular degeneration and diabetes.