“Trigger happy” visual field: Ten pointers

ABSTRACT

Background: While performing the visual field test, some patients press the response button, at random and not in response to seeing a stimulus, resulting in a classical trigger happy visual field. Purpose: This can be identified by 10 pointers as shown in this single field analysis printout of Humphrey visual field (HVF), 24?2, Swedish interactive threshold algorithm (SITA) standard test of the right eye. These points are useful teaching points for the students to recognize. Synopsis The video describes classical 10 points, which can be identified in an HVF 24?2 printout in a patient with high false?positive (FP) error. Highlights The FP index is the most useful of the reliability indices. In SITA strategy, the FP rate is based upon the assessment of patient’s reaction time over the entire course of the test, and hence is not calculated until the test is completed. Therefore, it is important for the perimetrist to be alert to recognize the signs early during the test, such as high fixation los s (despite good fixation as seen on screen monitor) and unusually high retinal sensitivity values (up to 50 dB), and reinstruct the patient. If the test is completed, it should be repeated. This is important as the FP rates >15% are associated with compromised test results and are automatically removed from the glaucoma progression analysis.