Diagnosis

Retinal examination

Figure eyeball

introduction

The examination of the retina serves not only to detect diseases of the eye at an early stage and to regularly check the course of the disease, but also diseases that can affect the entire body, such as high blood pressure or diabetes, can manifest themselves and be recognized in the eye. Early detection can often prevent or reduce possible consequential damage.

Methods of examination of the retina

The retina itself can best be assessed by using the slit lamp. In order to get the greatest possible insight into the eye, the patient is given eye drops beforehand. These drops widen the pupil.
However, there is a high level of glare for the patient because the pupil can no longer contract after the administration of these drops in order to regulate the incidence of light. However, the effect only takes place after 20 to 30 minutes and lasts a few hours before it wears off again.

When examining the retina with the aid of a slit lamp, a distinction is made between direct and indirect reflection.

Read more on the subject at: Fundoscopy

Direct reflection

With direct reflection, a three-mirror glass is placed directly on the eye as part of an eye test after instilling a locally anesthetic eye drop preparation. This glass removes the refractive power of the cornea and you can see the fundus. With the help of the mirror it is also possible to look "around the corner" and assess the periphery of the retina. This method is particularly suitable for being able to see cracks in the retina.

Indirect reflection

The slit lamp is also required for indirect reflection. In indirect reflection, magnifying glasses are used to look inside the eye. They are held at a certain relatively short distance in front of the eye. The magnifying glasses create an inverted image of the retina, which is enlarged by the slit lamp.

With reflections in general, the retina can be examined for various changes. For example, one pays attention to water retention (edema), excavations of the optic nerve papilla (the central dent of the papilla is too deep) and much more. These features suggest possible clinical pictures. The deepened dent at the optic nerve exit point can indicate increased intraocular pressure. You can also detect high blood pressure in the eye vessels.

Fluorescence angiography

If retinal hemorrhage or other vascular diseases are suspected, an examination method is used which specifically depicts the vessels of the retina: fluorineescent angiography.

A fluorescent dye (not a contrast agent) is injected into a vein, which is distributed over the blood and also flows into the vessels of the eye. The vessels of the choroid fill up first, because the blood supply to it is stronger, and they shine through the retina. The distribution of the dye is recorded by a special camera. The photos can then be used to diagnose water retention, bleeding, occlusions and much more.

What are the indications for a retinal examination?

Indications for an examination of the retina can be:

Macular diseases such as macular holes
Green star (glaucoma)
Macular degeneration
Retinal detachment (ablatio retinae)
Diabetic retinopathy
Retinopathia pigmentosa (retinal degeneration)
tumor

Does an examination of the retina make sense?

An examination of the retina can be used for early detection of various diseases of the eye, but existing eye diseases can also be diagnosed. For example, an examination of the retina can provide evidence of high blood pressure and diabetes, which are manifested by changes in the retina. But eye diseases such as glaucoma (green star) or degeneration of the macula (regression of the place of sharpest vision) can be discovered.

What are the risks?

An examination of the retina, especially an examination using a slit lamp, has few complications. Only in very rare cases do inflammations or infections occur as part of an examination of the retina. If necessary, the eye or the conjunctiva may then be slightly reddened or tear easily. These symptoms should go away on their own in a timely manner.

Since eye drops are often administered during an examination of the retina, which dilate the pupil, one can have an allergic reaction to them. This can manifest as itching or a burning sensation.

What are the costs for a retinal examination?

The cost of examining the retina varies widely. Depending on the procedure used to examine the retina, you can expect between 20 and 120 euros. The examination using a slit lamp is one of the cheaper services, while optical coherence tomography costs a little over 100 euros.

However, part of the benefits is paid by the health insurance company. In the case of existing illnesses or suspicion of an illness, the examination using a slit lamp is primarily taken over by the statutory health insurance companies.

Above all, preventive services or special examinations often have to be borne by yourself as a hedgehog service (individual health service). Here the costs can vary from practice to practice.

Who bears the costs?

The costs for an examination of the retina are usually not covered by the statutory health insurance. If there is a specific suspicion of illness, the costs for part of the examinations, for example a slit lamp examination, will be covered in appropriate cases. You should find out from your health insurance company which services are covered and which are not.

As a rule, the examination of the retina as part of a preventive check-up is an individual health service (hedgehog service). The costs can vary from practice to practice and are often not covered by the statutory health insurance.

If you have private health insurance, you should also ask the health insurance company which services are covered.

How long does a retinal examination take?

Before examining the retina, eye drops are often given to dilate the pupil. This is to ensure that the retina can be better examined. It takes about 15 to 30 minutes for these to work

Examining the retina itself only takes a few minutes. Depending on the method used, the time of the examination may differ slightly.

Since the eye drops often work longer, you shouldn't drive a car afterwards, as the eye drops that have dripped into the skin are blinded more quickly, as the pupil cannot constrict.

Can an examination work without dilation of the pupil?

An examination of the retina without pupil-dilating eye drops does not usually make sense, as the ophthalmologist can only look at the fundus with wide pupils.

In patients with glaucoma (glaucoma), however, the eyes should not be dripped with pupil-expanding drops, as there is a risk of a glaucoma attack.

Structure and function of the retina

The eyeball is made up of several structures. The wall includes all the “skins” that surround the inside of the eye. The interior includes z. E.g. the vitreous humor, the iris, etc.

The front part of the eye consists of conjunctiva, Cornea, Dermis, lens and Iris. The retina, along with the choroid and the vitreous humor, make up the back of the eye. It lies directly on the choroid and thus represents the innermost of all layers.

The retina, like the optic nerve, is an advanced part of the brain. It consists of different nerve cells. These are divided into several layers and contain around 130 million sensory cells.
There are two types of sensory cells:

Chopsticks and
Cones.

More information can be found here: Rods and cones in the eye

Rods are responsible for black and white vision and cones for color vision. These sensory cells show a certain distribution: the cones are mainly located in the center of the retina, while the rods are more in the periphery.
The largest number of cones is located in the so-called fova centralis (central depression), which can be found in the center of the retina.

The signals captured by the rods and cones are transmitted via several nerve cells to the optic nerve and from here to the brain. There are no sensory or nerve cells at the point where the optic nerve exits the retina and the eye. It creates the blind spot in the field of vision.

If you look at the retina (method see below) you can see characteristic features and structures: In the middle you can find the fovea centralis and further laterally outward the exit point of the optic nerve. The pupil has a rim and a normal central depression. This is also where the vessels enter the eye (retina and choroid). The vessels of the choroid are also visible because they shimmer through the retina. The missing vessels in the fovea centralis are noticeable.