Visual Field Testing Predicts And Confirms

by CRfan

Visual field testing in a powerful tool your eye doctor uses to diagnose and watch for progression of disease.

Eye doctors make it a point to test peripheral vision during eye exams. People use peripheral vision when they say, "I saw it out of the corner of my eye." Therefore, this type of visual field is tested by holding up fingers to the side of the eye, or by other similar methods.

Visual field testing is done for many reasons. First and foremost is to check for vision problems. Such tests can include screening for blind spots which are indicative of Glaucoma, and in some cases, pituitary tumors. Those who are near sighted, far sighted, or have astigmatism are tested according to their particular visual ailment. Regardless of current eye health, changes can appear at any given time in the future. This is why it is important to keep current with eye exams which include various screenings.

Visual Field Test Types

The Confrontation test is a basic test that involves covering each eye alternately while fixating on an object.  The object can be something like an ink pen or even the eye of the doctor himself.  Using the example of looking into the doctor's eye, a patient can expect to be asked if it appears that other parts of their face are missing.  A patient may also be asked to voice when a moving object is first noticed from the side.  If any major issues are noticed, the patient will be asked to partake in a more thorough test.

Automated Tests

Sometimes something known as Automated Perimetry is employed.  This includes flashing lights in a patient's side visual field.  Responses are recorded either verbally or by pressing a signaling device.  The amount of light used is pre-determined by machine.  Computer software analyzes all data for an accurate review.  Some such machines are able to compare multiple visual field tests to predict future vision changes.

A close up of the Humphrey Field Analyzer
A close up of the Humphrey Field Anal...
A patient using the HFA
A patient using the HFA

Automated Perimeter Types

The Humphrey Field Analyzer (HFA) is the standard in automated perimetry.  Many people are familiar with this process although the name may not be recognized.  This piece of equipment is used when a person is asked to place their chin in a chin rest.  The patient is also asked to fixate on lights which are flashed around the periphery. 

Another frequently employed testing process is known as FDT, or Frequency Doubling Technology.  FDT makes use of alternating white and black bars which flicker.  The flickering creates the illusion that there are twice as many bars as there actually are.  This test is intended to identify Glaucoma.  Studies suggest FDT is capable of detecting visual field changes up to four years earlier than the standard automated perimetry test.  FDT can be used as a screening aid to assess the visual field or to complete an in-depth field analysis.

An In-Depth Non-automated Visual Field

Updated: 06/12/2012, CRfan
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Mira on 02/23/2016

Interesting. I learned a few things. Thank you!

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