Examinations

There are various additional tests that the ophthalmologist or optometrist can request to make the diagnosis.

  • FAG research
  • OCT examination
  • Perimetry

FAG research

What is a FAG or FLU examination?
FAG or FLU examination is the mapping of the retina and blood vessels. FAG stands for Fluorescence Angiography. This examination is done for a large number of different retinal abnormalities. The retina is the light-sensitive part of the eye and is attached to the back of the eye. The retina is supplied with blood by two blood systems. One is the choroid system and the other is the retinal arterial system. To get a good picture of these blood vessels, a technique is required in which a contrasting dye is injected into the blood. The course of this dye can then be followed through the different blood systems.

In the past, a FAG examination was regularly performed. With the advent of the possibility of performing an OCT examination, this necessity has decreased considerably. The OCT examination usually provides sufficient clarity to make a diagnosis in order to be able to start treatment and to evaluate it afterwards.

Who is eligible for a FAG examination?
There are many diseases of the retina that lead to poor vision. The results of the photos indicate where exactly the abnormality is in the retina. This way the ophthalmologist can determine the treatment path. The examination can be repeated more often.

At the previous appointment you received eye drops from us. You should place these drops (Tropicamide and Phenylephrine) in both eyes 1 hour before the agreed time, every 15 minutes.

The examination
Upon arrival, it will be determined whether the pupils are wide enough and you will be taken to the function room. The photos are taken with a special camera. There is a chin rest in front of the camera on which you place your chin and place your forehead against the strap. You will see a small red flashing light that you should look at with one eye. Follow the photographer’s instructions carefully. First, some photos are taken without injection. Afterwards you will probably have to wait a while for the ophthalmologist. If this appears, you will receive a prick in the arm during which you will be injected with a yellow dye called fluorescein. The photographer starts taking photos during the injection. The photos are taken with a bright blue light with a flash. Some patients require an assistant to hold the eyelids slightly open. You should mainly concentrate on the red light and instructions from the photographer. After the examination you may experience blurred vision. This can last for a few hours. Your urine may also be yellowish in color during the first two days due to the dye and a yellow discoloration of the skin may occur.

After the examination
Due to the dilated pupils and bright lighting during the examination, vision may be somewhat blurred for several hours. We therefore advise you not to drive your own car after the examination. You will receive the results of the examination from your treating physician, and an appointment will be made for this. This usually takes place a week after the examination because the photos must first be assessed.

OCT examination

What is an OCT examination?
The abbreviation OCT stands for Optical Coherence Tomography. This technique allows us to create cross-sections of the eye with a very clear image. It can be compared to an ultrasound. With OCT we use light waves instead of sound waves. With OCT we can image different parts of the eye. We usually use an OCT examination to examine the retina, especially the macula. The macula, or yellow spot, is the central part of the retina. The macula ensures that you can see clearly. This allows you to read, recognize faces and watch television.

How does the OCT work?
An OCT works with infrared rays. The device sends these rays through the pupil to the retina. The different layers of the retina reflect the rays back to the device. This information allows the device to create a cross-section of the retina. The ophthalmologist can not only see that something is wrong, but also where exactly the abnormality is. Using the OCT, the ophthalmologist can monitor the abnormality and see whether the treatment is working properly.

What is the purpose of the examination?
The purpose of this examination is to make a diagnosis and/or make possible treatment possible. Your vision may temporarily deteriorate after the examination, this is due to the drops that are used. These scans are usually repeated to detect changes in the retina.

Who is eligible for an OCT examination?
Often your ophthalmologist will order an OCT if there appear to be problems in the central portion of the retina. The research shows the different disorders of the macula. The most important conditions are:

  • Macular edema: There is fluid in the macula. This occurs with diabetes, vascular blockages or inflammation.
  • Macular hole: There is a hole in your central retina.
  • Macula pucker: There is a membrane on your central retina and this distorts your vision.
  • Macular degeneration: This is wear and tear of the macula.
  • Glaucoma (abnormalities of the optic nerve)
  • Corneal abnormalities
  • Anterior chamber abnormalities

The examination
The OCT examination is painless and takes approximately 15 minutes. Please note that if you receive the results from the ophthalmologist immediately after the examination, drops may be administered. This will cause your vision to become blurred and your eyes may be sensitive to light. You may experience this for about 3 hours. We advise you not to drive the car yourself.

During the examination, you look with one eye through the infrared light at a blue dot. You should try to keep looking at the dot and blink as little as possible. You may blink when the person conducting the examination indicates this. Based on the various scans made during the examination, the ophthalmologist can make a diagnosis and/or start possible treatment.

After the examination
You will receive the results of the examination from your treating physician. If possible, an appointment will be made immediately after the examination or otherwise a separate appointment will be made.

Perimetry

What is perimetry or a visual field examination?
The visual field is the surrounding vision, also called peripheral vision. When we look at a certain point with one eye, we see much more than just that point. We see a large area, although less sharply than the point we are looking at. This entire area is the visual field. The entire visual field is of great importance in daily life, for example to prevent us from bumping into something or tripping. If (part of) the visual field is lost, one has a kind of blind spot. It is possible that someone with 100% vision, still has large parts of the visual field missing. The visual field is tested by means of a visual field examination with an automatic computer-controlled perimeter. A visual field examination serves to detect and record any loss in the visual field. It is a difficult and sometimes tiring examination. It requires some concentration from the person being examined. Often multiple examinations are done because there is a learning curve for this examination.

Who is eligible for a visual field examination?
There are many conditions that cause visual field abnormalities. The shape of the visual field is characteristic of the condition. The most common reasons for a visual field examination are:

  • high eye pressure
  • glaucoma
  • neurological abnormalities (cerebral hemorrhage or increased intracranial pressure)
  • optic nerve abnormalities
  • medication use
  • unexplained low vision
  • driver’s license inspection

The examination
The examination is painless and drops are not administered to your eyes. The examination takes approximately 15 to 40 minutes. During the examination, you look at the lights in the center of a sphere with one eye. Your other eye is covered with a cap. Try to keep looking at the lights in the center of the sphere, while small points of light appear in other places. When you see a bright spot appear, you have to press a button. In this way, the doctor can examine your entire visual field and determine whether there are any abnormalities. Try to follow the instructions as best as possible during the examination. A reliable result is important to make a good diagnosis.

After the examination
You will receive the results of the examination from your attending physician, for which an appointment will be made. As already mentioned: sometimes the examination must be repeated to be able to make a diagnosis.