Ocular fundus examination

Synonyms in a broader sense

Control of the ocular fundus, observation of the retina, retinal mirroring, funduscopy, ophthalmoscopy

What is the purpose of the investigation?

An examination of the eye fundus is normally not necessary as long as the patient has no complaints and has never had problems with the eye and especially the fundus in the past. The examination of the fundus of the eye is an informative and important examination, as many diseases can be detected and controlled by this examination. How often the patient should come for a fundus examination depends on the individual case and has to be decided by the treating physician. The retina as well as the optic nerve head (papilla) can be examined and important supplying structures, such as the blood vessels, but also the place of sharpest vision (fovea) can be assessed. Not to be confused with intraocular pressure measurement, which has to be paid by the patient himself and is nowadays suspected to be too often performed unnecessarily and without diagnostic benefit.

Principles of the investigation

During the examination a relatively strong light falls on the retina, which can be disturbing for people who are sensitive to glare. The examination room itself should be darkened so that the ophthalmologist performing the ocular fundus examination is not dazzled from the outside during the examination and the examined structures can be better recognized and assessed. In order to dilate the pupil and thus gain a better view of the fundus of the eye, dilating eye drops are usually given.

In most cases, this administration is without further side effects. However, it should first be ensured that the patient does not have an excessively flat anterior chamber of the eye, as the dilation of the pupil can increase the intraocular pressure and thus the risk of an acute glaucoma attack in the patient. In this case, the intraocular pressure increases considerably, pain is experienced and there is a risk of permanent visual impairment.

However, since the ocular fundus examination usually takes place in an ophthalmologic clinic or practice, the patient is cared for for the duration of the effect of the drops and if the typical symptoms occur, an appropriate counter therapy is initiated. It is important that the patient is not allowed to operate a vehicle with the pupils dilated by the drops. Only when the effect has subsided a few hours after the examination of the back of the eye, the patient may drive a car again.

If it is not possible to use the eye drops, the ocular fundus examination can still be performed: However, the ophthalmologist then has only a limited view of the eye fundus and can judge subtleties and details worse due to the limited illumination. However, this is often sufficient to obtain an orienting overview of the condition of the fundus of the eye. Direct reflection of the fundus (direct ophthalmoscopy) produces an upright image.

The examiner holds an electrical viewing device at a short distance from the eye. It may be necessary to add corrective lenses in the electric ophthalmoscope (Rekoss disc) in order to see a sharp image. These lenses are also required for spatial measurement.

In direct ophthalmoscopy (retinal mirror), a high magnification is achieved, but only a small part of the back of the eye can be seen. Since an upright image is produced here, even an untrained examiner can assess the findings more easily. Most ophthalmologists prefer the indirect reflection of the fundus of the eye.

The examiner uses a pupil light to illuminate the area of the fundus of the eye to be examined. The other hand holds a magnifying glass in front of the patient’s eye, whereby the doctor sees a mirror-inverted and upside-down image. At the doctor’s command, the patient looks in different directions so that the different areas of the retina can be seen and assessed by the doctor. There are also special devices that allow the examination with both eyes instead of one, so that a three-dimensional image of the structures of the retina can be seen. With indirect mirroring (indirect ophthalmoscopy), large areas can be viewed and thus an overview of the retina can be obtained.