Your job as the perimetrist is to enhance patients' ability to respond accurately, thereby eliminating false positives and false negatives in visual field testing. The first steps to an accurate visual field test include setting patients at ease, making them physically comfortable in position at the perimeter, and ensuring that they understand the task. Paying attention to patients, encouraging them, and preventing distractions all augment the success of the testing.
The following strategies increase the accuracy of automated perimetry:

  • Advise patients to respond promptly, but not in haste, when they see a brief stimulus.
  • Test a patient's better-seeing eye first, especially if he or she has not undergone perimetry before.
  • Completely cover the eye not being tested.
  • Properly position patients at the perimeter. This reduces their fatigue and helps them to maintain proper ocular alignment. Both affect the test result.
  • Remember that best-corrected distance refraction is critical. Correct for cylinder of more than 1.00 D during the visual field test. Accommodating adds are considered according to the patient's age.
  • Bear in mind that four circumstances require a full add (+3.25 D) for perimetry: (1) age greater than 60 years; (2) pseudophakia or aphakia; (3) cycloplegia; and (4) myopia greater than -3.00 D.
  • Use a full-aperture lens with a narrow metal rim around the glass, not a lens with a broad rim around a smaller glass.

INSTRUCTIONS FOR THE VISUAL FIELD TECHNICIAN

Review the last clinical note for visual field instructions. Most clinicians generally prefer a SITA-Standard 24-2 algorithm, but they may sometimes want to use SITA-Fast, short-wavelength automated perimetry (blue on yellow), and 10-2 strategies.

Take a thorough history and complete the front page of the clinical note. Do not leave any sections blank. Always check the patient's best-corrected distance and near visual acuity before the visual field test. Refract all new patients and also returning patients who have a change in visual acuity. Always record the refraction in the clinical note and on the visual field.

Assess pupillary size. If pupil is less than 3 mm in diameter, ask your doctor about possible dilation before performing visual field testing. Only dilate the pupils of patients with your doctor's approval. Always record the pupil's size on the visual field test. Fortunately, the pupil's size is measured automatically when the gazetracking function is on.

Be sure always to use a size III stimulus unless told otherwise. Foveal function should always be on. The foveal function helps clinicians to determine the etiology of visual field loss.

Pay close attention to the patient during the visual field test. Encourage and instruct him or her as necessary. Assess his or her reliability, concentration, eye and head movement, and understanding of the examination. Record your assessment at the bottom of the visual field. Include your name on each visual field test you perform.

Report to your doctor any questions or difficulties you encounter during visual field testing.