Electrophysiological discrimination between retinal and optic nerve disorders

In this study we show how the Pattern ERG (PERG) can be used to distinguish between optic nerve and retinal disease. Records from eyes with RBN and delayed visual evoked responses are compared with those recorded from the normal fellow eyes. In optic nerve disease there is a selective reduction of the later negative component of the PERG. PERGs were also recorded from patients with mild diabetic retinopathy. These were divided into three groups on the basis of the delay in their Visual Evoked Potential (VEP). The amplitude of both positive and negative components of the PERG fall with increasing severity of the disease thus showing that the abnormally long delay in VEP found in some cases is due to retinal disease rather than optic nerve disease.

Computerized localization of sources of evoked potentials in the assessment of visual field impairment

Objective computer-based techniques are described along with their underlying theoretical rationale for investigating visual field disorders. The paper concerns methods for the collection and analysis of evoked potentials and provides a description of methods for obtaining information about the conduction pathways of the visual system for clinical, neurological and neuropsychological applications.

Clinical uses of the visually evoked potential

The visually evoked potential is defined and described. The development of this test as a valuable clinical aid is traced. Its assistance in the diagnosis of Lesions of the Optic Nerve and Visual Pathways is shown, together with its use and assessment of visual acuity and visual fields both in infancy and adults. Future developments of this test are reviewed.

Neurophysiological investigation in optic nerve disease: combined assessment of the visual evoked response and electroretinogram

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Effect of body temperature on visual evoked potential delay and visual perception in multiple sclerosis

Seven multiple sclerosis patients were cooled and four heated, but evoked potential delay changed in only five out 11 experiments. Control limits were set by cooling eight and heating four control subjects. One patient gave anomalous results in that although heating degraded perceptual delay and visual acuity, and depressed the sine wave grating MTF, double-flash resolution was improved. An explanation is proposed in terms of the pattern of axonal demyelination. The medium frequency flicker evoked potential test seems to be a less reliable means of monitoring the progress of demyelination in multiple sclerosis patients than is double-flash campimetry or perceptual delay campimetry, although in some situations the objectivity of the evoked potential test would be advantageous.

Assessment of visual field impairment by objective technique

An objective psychophysical technique for investigating visual fields by averaged scalp potentials evoked by pattern gratings of alternating contrast and by sinusoidally modulated flicerking light is applied to a child with a right homonomous hemianopsia. This technique illustrates a value, in obtaining clinical data on visual fields in situations were subjective perimetry is difficult to administer or where conservating diagnostic methods do not yield evidence of pathology.