How to interpret visual fields

Imagine you are assessing a patient with visual difficulties or optic disc swelling. After a bedside visual field examination with waggling fingers and even a red hatpin, you decide that there is an abnormality. After requesting quantified visual field tests, the patient returns with a black and white printout with numbers (eg, Humphrey fields) or coloured lines on a sheet (eg, Goldmann fields). Where is the report you ask? There is none! Static perimetry uses flashing stationary lights. This can be automated (eg, evenly spaced points on a grid) or manual (eg, as a small part of Goldmann test: detailed later). The Humphrey field analyser is by far the most commonly used for automated static perimetry, although there are also other machines such as Octopus and Henson. Later, we describe in detail the interpretation of Humphrey perimetry. Kinetic perimetry uses a moving illuminated target and is done either manually (eg, Goldmann) or on an automated machine (eg, Octopus). Goldmann machines are no longer manufactured, being slowly replaced by Octopus machines. Nevertheless, Goldmann remains the most commonly used kinetic perimetry, and so we use this here to illustrate interpretation of kinetic fields. The principles for interpreting Goldmann also apply to results from Octopus machines. It is beyond the scope of this paper to cover the neuroanatomical localisation of visual field defects. Instead we recommend two excellent recent reviews.1 ,2 Skilled interpretation of visual field tests requires a good grasp and application of this prior knowledge. ### Useful aspects of eye anatomy 1. The fovea is the area of greatest visual sensitivity, where the cone photoreceptor density is at its highest. The visual sensitivity slopes off further from the fovea. This drop in sensitivity can be visualised as a hill, with the fovea is at the peak (figure 1). Conventional perimetry is carried out under photopic (well …