Visual fields

1. Gross testing by CONFRONTATION. Compare the patient's fields of vision by advancing a moving finger or, more accurately, a red 5 mm pin from the extreme periphery towards the fixation point. This maps out 'cone' vision. A 2 mm pin will define central field defects which may only manifest as a loss of colour perception.

In the temporal portion of the visual field the physiological blind spot may be detected. A 3 mm object should disappear here.

The patient must fixate on the examiner's pupil.

Patient

Examiner

Test object

Examiner

Patient

Test object

2. Peripheral visual fields are more sensitive to a moving target and are tested with a GOLDMANN PERIMETER.

The patient fixes on a central point. A point of light is moved centrally from the extreme periphery. The position at which the patient observes the target is marked on a chart. Repeated testing from multiple directions provides an accurate record of visual fields.

Fixation point

Fixation point

240 255 270 285 300 RIGHT

GOLDMANN EYE

PERIMETER

T20 105 90 75 60 Peripheral

.45 field

,30 Central , field

240 255 270 285 300 RIGHT

GOLDMANN EYE

PERIMETER

3. Central fields are charted with either a Goldmann perimeter using a small light source of lesser intensity or a TANGENT (BJERRUM) SCREEN. The HUMPHREY FIELD ANALYSER provides an alternative and particularly sensitive method of testing central fields. This records the threshold at which the patient observes a static light source of increasing 10 intensity.

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