Automated perimetry and malingerers. Can the Humphrey be outwitted?

BACKGROUND

Through detailed strategies and sophisticated analysis, the Humphrey automated visual field analyzer attempts to indicate if visual field loss is artefactual. Can these measures be outwitted by malingerers?

METHODS

The author investigated the ease with which motivated individuals (such as are malingerers) could simulate visual field defects consistent with organic neurologic disease on the Humphrey visual field analyzer. Visual field test results were analyzed for characteristic features and compared with visual field tests from patients with documented pituitary tumors.

RESULTS

Volunteers, given only broad suggestions as to the visual field they were to simulate, produced consistent, convincing, neurologic-type field defects, according to textbook descriptions of such fields. These plotted fields were only distinguishable from genuine pituitary tumor Humphrey field tests, in that they more convincingly fitted the classic descriptions of visual fields seen with chiasmal compression.

CONCLUSIONS

The author concludes that single routine Humphrey visual field tests do not show malingerers. An incidental finding of this study was the extent to which Humphrey visual fields from patients with genuine neurologic disease contain field defects with characteristics different from those of the (kinetic) visual field test appearances described in the textbooks.