Visual field testing is an eye examination performed in conjunction with a basic eye examination in order to measure central and peripheral vision. The test can be used to evaluate and rule out glaucoma and to evaluate the integrity of the visual pathway. Small blind spots in the visual field begin to appear early in glaucoma. The visual field examination may detect diseases that affect the eye, optic nerve, or brain and screen for visual sequelae of cerebrovascular injury or head or eye trauma. There are several types of visual field tests, such as the confrontation visual filed examination, which measures peripheral vision, and automated perimetry test, which is a computerized measurement of the visual filed.
Confrontation Visual Field Examination
Position the patient at eye level to the tester.
Have the patient cover one eye and focus the other eye directly on the tester's eye.
Ask the patient to respond with how many of the tester's fingers can be seen (without moving their gaze).
Repeat the examination with the other eye.
Automated Perimetry Test
Position the patient in front of the visual field analyzer and ask them to place the forehead against the machine (Figure 16.1).
Instruct the patient to stare at the fixation light.
Ask the patient to click a button when they see lights of varying intensity that are displayed at intervals.
Inform the patient that the procedure time is about 5-10 minutes for each eye.
Abnormal findings show the depressions of sensitivity that appear in glaucoma or pathology affecting the optic nerve (i.e., ischemic neuropathy).
Positive results should be confirmed with a repeat examination.
Pretest Patient Care
Explain the purpose and procedure of the test.
If evaluating for glaucoma, explain that risk factors include age, race, family history, and elevated intraocular pressure.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results and counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. Modify the nursing care plan as needed.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.