Visual Field Testing
The visual field is a complete area that can be seen when your eyes focus on a single point; this comprises of objects that can be seen on either side, and above and below the point that your eyes focus on. Visual field tests are diagnostic tests used to measure the entire scope of vision, which includes the central and peripheral (side) vision.These are most commonly used to evaluate any damage to the optic nerve. They are also used to detect and monitor retinal diseases, drooping of the eyelids and conditions affecting the visual pathways in the brain. The examination helps to determine the loss of vision in the visual field. The visual field examination is performed in different ways:
- Confrontation visual field exam: This is a primary examination, during which the clinician asks you to cover one eye and look straight ahead. The clinician stands at a distance of 3 to 4 feet and moves his/her hand towards and away from your field of vision. You are instructed to indicate when you can clearly see the examiner's hand.
- Tangent screen or Goldmann field exam: You are seated about 3 feet away from a screen with a target in the centre. You are instructed to stare at the centre and inform the clinician when you see an object moving into your side vision. Your clinician uses this information to create a map of your field of vision. This helps Dr Chiu detect areas of blindness in your visual field.
- Automated perimetry: You are seated in front of a concave dome and instructed to stare at an object in the centre. You are instructed to press a button when you observe small flashes of light in the peripheral vision. Computer images will help in determining defects in the visual field. Humphrey visual field testing is the gold standard of automated perimetry. If you have had previous field tests and are referred to Dr Chiu, the field test may need to be repeated if it does not meet not the gold standard of testing.
Dr Chiu or her staff will discuss the type of visual field examination to be done.