Evaluation of visual pathways in multiple sclerosis. I. After-images compared to visual evoked potentials

The value of flight of colours (FOC), i.e. the succession of coloured afterimages following light stimulation, in diagnosing and following visual impairment was evaluated in 65 patients with multiple sclerosis (MS). Previous optimistic reports of the use of a pocket flashlight (PFL) method could not be confirmed, and are ascribed to inadequate methods. An electronic flashlight (EFL) method developed by us, proved a significantly better diagnostic tool (61% abnormal versus 18% abnormal). The EFL method was diagnostically less sensitive than pattern reversal visual evoked potential (PR-VEP) (80% abnormal). It did, however, add to PR-VEP by diagnosing 16 eyes with normal PR-VEP latency. The EFL method reflected the degree of degenerative changes in the central visual pathways and may be of value in following the disease activity in MS. The potential of the EFL method may be further improved by proposed modifications.