The eyes, optic nerve, and occipital lobe of the brain collaborate with each other to maintain vision through the visual pathway. Everything that we see while focusing on a single point is considered our visual field.
If anything disrupts the normal structure of the optic pathway, it can result in visual field defects. Visual field defects are usually not apparent in their early stages as the eye compensates for the loss in the visual field by distorting the perceived image. However, if left undiagnosed and untreated, visual field defects may progress further and significantly impair vision. Several tests that diagnose asymptomatic visual field defects are available, but the most common among these tests is the automated visual field test.
The automated visual field test is a tool used to detect defects in peripheral vision. While the most common indication of a visual field test is to screen, diagnose, determine the severity, and monitor the prognosis of glaucoma, the automated visual field test can detect numerous other eye conditions as well.
Sudden vision loss of a particular pattern may occur as a result of devastating neurological conditions such as stroke, traumatic brain injury, or brain tumors compressing the visual pathway. Identification of the pattern of visual field defect can help determine the location of the neurological injury. Automated visual field test can be used to detect visual field defects caused by the following conditions:
The automated visual field test is usually done in a separate room, unlike other optic tests which may be done in your doctor’s room. It is because this test requires a dark room where no other visual stimulus is present while performing the examination. One eye is examined at a time, and the other eye may be covered with an eye patch to minimize errors.
Once your personal details are entered into the machine, you will be asked to rest your chin on the chin rest with your forehead supported by the forehead rest. There is usually an attached lens holder inbuilt on the machine where your prescription glasses or lenses can be adjusted accordingly. You do not need to wear your prescription glasses during the examination.
As the examiner turns off the light and the room becomes pitch black, you will be able to see an orange dot in the bluish background on the screen. You will be asked to focus on the orange dot throughout the examination. The examiner will give you control of a switch where you will be asked to press whenever you see a flash of light during the process. Even when there is a flash, do focus on the orange dot during the examination.
It is okay to miss some of the flashes of light while undergoing the test. The machine records the points at which the flashes of light emitted got missed. Some of the dim flashes may be missed, and the examiner may increase the brightness of the light to the point until which the orange dot is still visible to the patient. You can alert your examiner if you experience any inconvenience. The result is given instantly, and the data can be interpreted by the specialist.
Apart from an automated visual field test, there are several tests that can be used to detect visual field defects. Some of them are:
While this test has its own significance, automated static perimetry or automated visual field test is preferred among the above tests for several advantages it provides over the other methods, such as:
Although automated visual field tests are the preferred investigation over other visual field tests, there are some disadvantages of this test. The possible setbacks of automated visual field testing are as follows:
Automated visual field test or automated static perimetry is an investigation used to detect defects in the visual field. It is superior to other available visual field tests as it provides a greater range of detection of visual field defects and is helpful in screening glaucomatous changes early. It has minimal setbacks and is the preferred investigative tool to detect focal defects of the visual field.
