Diagnosis

Visual field examination

What is the field of view?

The field of vision describes the region or environment in which the eye can perceive objects.
So how far can the patient perceive something in the upper field of vision without looking up, for example? The same applies to the field of vision below, right, left and of course everything in between (upper right, etc.).
The values determined by a visual field examination are given in degrees.

The cooperation of the patient is of great importance in order to achieve representative and usable results.

General

For orientation, even the non-medical practitioner can use very simple means to get an impression of the field of vision and also of any possible failures.

All that is needed is a narrow object (a pen would be conceivable) and an eye cover (usually the patient simply covers his eye with the palm of his hand).
Here too - as with the visual acuity test - each eye is tested individually. Because each eye can have a failure that can possibly be compensated for by the other eye. Both eyes are checked individually so that such important details are not overlooked.

The examiner sits across from the patient. Both hold the opposite eye to each other.
(If the patient covers their left eye, the examiner must cover their right eye and vice versa.)
The fact that the examiner also turns a blind eye is used for comparison.
In the amateur test, the examiner's field of vision functions as a reference value in order to be able to detect gross deviations.

Now an object - the pen - is brought into the field of vision from all sides. The patient indicates when he sees the object for the first time. It is important that the eyes are fixed on each other and do not move, but always look straight ahead. The head must also be kept absolutely still.
If the field of view is normal, the doctor and patient see the object at the same time. This process is repeated for the other eye.

This approximate method can be used to quickly identify failures. Here, for example, there is the possibility that a quarter or even half (right or left) of the field of view has failed. Isolated failures also occur.
In the case of glaucoma, for example, only central parts of the field of vision may have failed.

How is the process?

The process of a visual field examination depends on the type of test.
There are different variants for the examination:

In so-called finger perimetry, the examiner examines the visual field by moving his fingers from back to front into the patient's field of vision.
As soon as the patient perceives this, the patient reports.
In this way, the limits of the field of view can be roughly and quickly assessed.

With so-called static perimetry, the patient's head sits firmly in a device. His eyes fix the center of a hemisphere in which points of light shine. If the patient perceives this in his field of vision, he reports.
With the device it is also possible to measure the examination with different light intensities in order to achieve a better result.

How long does the examination take?

The roughly orientated finger perimetric examination of the visual field takes only a few minutes.

The static examination of the field of view usually takes around 15-20 minutes.
The treatment is neither invasive nor painful.
You don't need much preparation and you don't have to be sober.

The only thing that is required is a high level of concentration and willingness to cooperate.

Static perimetry

Our field of vision is measured precisely using perimetry.

At the ophthalmologist's or eye clinic, the field of vision is measured more precisely: with the help of an apparatus called a perimeter. Here, too, each eye is measured individually, with the head held still and the eye looking straight ahead. The apparatus appears as a hemisphere in the middle of which there is a fixation point, which the patient must aim at. Now a point of light is brought into the hemisphere from outside. Again, the patient must give notice when he first perceives the point. Again, all directions are tested (up, down, right, left, up left, up right, etc.). In this way, the dimensions and possible failures can be determined precisely with precise degrees.

The “blind spot” is referred to as a physiological finding. This is quite normal and is present in everyone. This is the exit point for the optic nerves at the posterior pole of the eye.
There are no photoreceptor cells here. In everyday life we do not notice the "blind spot" and do not affect us in any way.

How is the evaluation carried out?

The evaluation of a visual field examination is the responsibility of an ophthalmologist or a specialized optician.
The investigation provides a number of data and graphs. With the help of this data, the doctor can now determine in which area there is a loss of visual field and thus identify possible causes.

As a rule, two crosses are seen in the graphics, which represent the two eyes.
There are dots or similar around the crosses. entered in order to be able to display the field of view.
Ideally, an approximately circular shape should emerge on both sides at the end.

Physiologically, the field of vision is wider outwards than inwards, as the nose restricts the field of vision on the inside of both eyes.
If there is now a disease that leads to visual field defects or the like, this can be seen from the missing entries in the diagram.

By interpreting these failures, one can now infer the completeness of the visual field, but also the size and location of dark spots, so-called scotomas.
Further causes can then be specified for the exact diagnosis.

Possible outcomes

Defects in the visual field are called scotomas. There are different types of scotomas.

The deficits can be centrally located at the point of sharpest vision and thus impair visual acuity, or they can be outside the center.

Complete failures also occur. Quarter or even half of the field of view may have failed.

What to do if the result is bad

If the result is poor, further examinations are usually undertaken.

Often times, patients complain of dark spots in their vision, so a bad result is not surprising.
Conversely, abnormalities in the visual field are relatively rare in healthy patients.

Through the examination, the doctor can now say more precisely where the cause could be and therefore carry out more specific examinations.
In some cases, for example, a CT scan of the head is then carried out.

This article might also interest you: Radiation exposure in computed tomography

How high are the costs?

The cost of a visual field examination depends on the underlying disease and insurance.
For some patients with proven visual disturbances or eye diseases, the examination is covered by the health insurance, both statutory and private, and is therefore free of charge for the patient.

The examination is also often free of charge for different professional groups who have to undergo regular eye examinations.
This includes, for example, pilots or drivers.

If you want to do a visual field examination for other reasons, it usually costs no more than 15-20 €.

Is that covered by the health insurance?

In most cases, the costs of a visual field examination carried out are covered by health insurance companies.
The reason for reimbursement of costs can, for example, be an existing eye disease that requires frequent check-ups.

Often, however, the assumption of costs also depends on whether you have statutory or private insurance.
To be on the safe side, you should contact your health insurance company to find out if the costs are covered.

In the case of statutory health insurances, the treatment is often only considered an IGeL service.