The flight of colours test. Its value as an indicator of dysfunction of the visual pathways

The flight of colours (FOC) test was compared with visual evoked potentials (VEPs) in 135 patients in a 2 year prospective study, to determine whether the FOC test is a sensitive and reliable alternative. We obtained an 80% overall agreement between the tests, confirming the levels of agreement reported by Rolak (87%) and Swart and Millac (92%). Abnormal VEPs, however, were more closely associated with cases of clinically definite multiple sclerosis (MS) while abnormal FOCs were more frequent in cases of non-demyelinating disease and cases without clinically evident optic nerve or other ocular disorder. We cannot explain this result by any demonstrated superiority of the FOC test over VEPs in non-demyelinating visual disturbances, whether clinically evident or not. Thus the study does not confirm the earlier expectation that the FOC test would be a reliable alternative to the study of VEPs in the differential diagnosis of MS.