Visual Field Testing Flashcards

A patient undergoing automated perimetry consistently presses the response button when no light stimulus is presented. On the Humphrey Field Analyzer printout, this will be recorded as a high number of:

Answer: False positives

False positives occur when a patient responds (presses the button) in the absence of a light stimulus. This indicates that the patient is "trigger happy" and can compromise the reliability of the test results.

Which of the following visual field defects is most characteristic of advanced, untreated glaucoma?

Answer: Arcuate scotoma progressing to a nasal step

Glaucoma typically damages the optic nerve fibers in a characteristic pattern, often starting with an arcuate (arc-shaped) scotoma that follows the path of the nerve fiber layer. As it progresses, this can lead to a "nasal step" defect. Bitemporal hemianopia is associated with chiasmal lesions, a central scotoma with macular disease, and altitudinal loss with vascular events affecting the optic nerve.

A technician is preparing a patient for a Goldmann visual field test. Which of the following describes the stimulus presentation method used in this type of perimetry?

Answer: A moving light stimulus of a set size and intensity brought from non-seeing to seeing areas.

Goldmann perimetry is the primary example of kinetic perimetry. In this method, a light stimulus of a specific size and brightness is moved from the periphery of the visual field toward the center until the patient indicates they can see it. This process maps out isopters, or areas of equal retinal sensitivity.

During a Humphrey visual field test, the instrument checks for fixation losses by presenting a stimulus in which location?

Answer: The patient's physiological blind spot

The Humphrey Field Analyzer uses the Heijl-Krakau method to monitor fixation. It first maps the patient's physiological blind spot and then periodically presents stimuli within that area. If the patient responds to a stimulus in their blind spot, it indicates they have shifted their gaze from the central fixation target, and a fixation loss is recorded.

A patient with a pituitary tumor compressing the optic chiasm would most likely exhibit which type of visual field defect?

Answer: Bitemporal hemianopia

The optic chiasm is where the nasal retinal fibers from each eye cross over. A lesion, such as a pituitary tumor, pressing on the center of the chiasm damages these crossing fibers. This results in the loss of the temporal (outer) visual fields in both eyes, a condition known as bitemporal hemianopia.

When instructing a patient for their first automated visual field test, which of the following is a critical instruction?

Answer: "Keep looking at the central fixation light and press the button for any light you see, even if it's dim."

Proper patient instruction is crucial for a reliable test. The patient must maintain steady fixation on the central target throughout the test and respond to any stimulus they perceive, regardless of its brightness. Looking around for the lights results in fixation losses, and only pressing for bright lights will inaccurately map their field.