IN-vision

This section is intended for use by optometry students who wish to gain an insight into the types of examination techniques that can be applied to a patient who appears to have nystagmus.

History and symptoms

Make sure to ask if there is a family history of nystagmus or of the conditions that are commonly associated with nystagmus. The further back any problems can be traced the better as, due to the inheritance mechanisms, many conditions can skip several generations.

Ask about the observed time of onset of the symptoms and their characteristics such as their progression and changes in severity under different conditions e.g. lighting, stress etc. An intermittent problem may impede the examination process as it may or may not appear during the examination.

Also ask about any visual difficulties that the patient has experienced such as photophobia or poor night vision as these may indicate an underlying sensory defect that may be the cause of the problem. Make sure to enquire about any previous treatment that they could have received such as surgery or any medication that they may be taking.

Ocular examination

A full examination should be carried out which should include ophthalmoscopy, slit-lamp, colour vision testing and refraction. Measure the patient’s visual acuity binocularly and monocularly, at distance and near and with and without a head turn if applicable.

Oculomotor examination

Axis

Determine the axis of the oscillations as horizontal, vertical, oblique, torsional or circumrotatory. Small or torsional oscillations can be observed by viewing fundus movements through an ophthalmoscope.

Asymmetry

Record any asymmetry in oscillations that occurs between the two eyes and in what position of gaze it appears.

Gaze-dependency

Record any changes in the oscillations that occur following a change of gaze position.

Monocular occlusion

Occluding one of the eyes will reveal any latent component of the nystagmus.

Electronystagmography

Eye movement recordings allow accurate classification of the nystagmus waveform.

Electrophysiological examination

These types of examination techniques are rarely available but can be useful, for instance, the determination of normal electroretinography and pattern visual evoked potentials is an indication of an IINS. Abnormal results in these electrophysiological tests can reveal less obvious sensory defects that may be present or identify a neurological abnormality.