The usual clinical 24 degree visual field has 54 points. Standard visual field defect detection is based on testing these individual points one by one. Moreover, each individual point may have to be tested a few times in order to determine the retinal sensitivity there. The retinal sensitivity at each point is then compared to a ‘normative’ database. The retinal sensitivity is then statistically either ‘within normal limits’ or ‘outside normal limits’.
Other computer based visual field or iPad based tests imitate this point by point testing.
Visual field fast displays the stimulus everywhere in the area to be tested. The observant viewer may then see and identify visual field defects.