PATIENT EDUCATION

Humphrey visual fields

This test is used to detect blind spots or scotomas in the visual field which could be a sign of an eye or a neurological disease. The nature of such blind spots (shape, size, depth) can point towards different disorders of eye, optic nerve or visual pathway in the brain.

Indications:

  • Glaucoma
  • Optic nerve pathologies
  • Retinitis pigmentosa
  • Drug toxicities
  • Brain tumours
  • Stroke

Preparation:
Patient must have minimum vision of 3/60. There is no need for dilatation. However, if this test is initially done under dilatation, the subsequent tests must also be done under dilatation in order to ensure comparability.

Procedure:
The patient’s head is placed on a chin rest inside a large bowl-like instrument. The patient is asked to look at a source of light straight ahead and lights of different intensities are flashed from random points in their visual field. Each time the patient sees the light, he or she has to immediately press a button which is recorded by the instrument. The information thus gathered and processed. Sometimes it is also compared with age matched normative data in order to decide whether the findings are normal for that particular population.

The report thus obtained gives an idea of the shape of the scotoma which helps in diagnosis and the extent and the depth of field loss which helps us to understand the severity of the disease.