What is the role visual field testing in the evaluation of a glaucoma suspect?

Updated: Jul 27, 2020
  • Author: Robert H Graham, MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Results of visual field testing should be normal.

Absence of visual field defects does not ensure absence of glaucoma.

As many as 50% of optic nerve fibers in a single optic nerve may be damaged before visual field defects are found by Goldmann perimetry.

Common pitfalls in visual field testing are as follows:

  • Pupillary diameter should be maximized

  • Correct refraction should be used

  • Patient reliability is limited in some cases

Interpretation of visual field testing: Use comparable tests when comparing fields. For example, one cannot directly compare Swedish interactive thresholding algorithm (SITA) with Fastpac or HVF 30-2 threshold testing. If a field defect is detected, ensure that it is reproducible. The abnormal points should be contiguous, paralleling the pattern of the nerve fiber layer in an arcuate pattern respecting the horizontal midline. The greater the abnormal points and the deeper the defects, the more likely it represents a true scotoma.

The standard testing strategy used by many ophthalmologists in past evaluations has been HVF 30-2 or 24-2 traditional threshold testing with statistical analysis.

Humphrey Fastpac requires less testing time; decrease in precision of threshold algorithm estimate.

SITA reduces testing time by about 50% without sacrificing accuracy. Less interindividual variability occurs, and gray scale printouts may look lighter.

Short wavelength automated perimetry (SWAP) uses blue target on a yellow background to isolate those visual pathways that are believed to be damaged selectively in early glaucoma. Many studies suggest that it is capable of earlier detection of glaucomatous defects, which may be useful in detecting progression to glaucoma in those patients who are glaucoma suspect and at a high risk. [32, 33] It requires longer testing time with 3-minute adaptation to yellow background.

Frequency-doubling technology perimetry uses a coarse striped grating of rapidly alternating dark and light bands. It takes 4-5 minutes for each eye; screening test takes less than 1 minute. A potential role exists in diagnosing early glaucoma and in detecting moderate-to-advanced glaucoma. [34] Liu et al suggest that frequency-doubling technology is effective in monitoring visual field progression and that it may detect field defects earlier than standard automated perimetry. [35]

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