In keratoconus, the cornea of the eye becomes thinner and thinner and bulges forward like a cone. The eye disease becomes noticeable because those affected have distorted, blurred and out-of-focus vision. Keratoconus often begins at a young age and then develops slowly. It is still unclear why the cornea thins out. Researchers suspect that genetic factors are at work. Keratoconus can be treated with contact lenses, glasses or eye surgery.
What is keratoconus?
Keratoconus is a degenerative eye disease in which the cornea thins out and bulges forward like a cone. This is where the name comes from: “kerato” is derived from the Greek term kéras (= horn) and “cone” comes from Latin and means “cone”. The eye disease is also called corneal cone. Nothing is known about the causes and development of keratoconus.
Keratoconus usually develops slowly and insidiously. Keratoconus usually manifests itself through visual impairment: Those affected only see their surroundings blurred, distorted or double. As a rule, keratoconus affects both eyes: first the symptoms start in one eye, then in the other. The eyes are then often affected to varying degrees.
Keratoconus can initially be corrected well with contact lenses. However, if the eye disease progresses further, surgery is the treatment of choice. There are various surgical techniques, for example the relatively new corneal crosslinking or a corneal transplant. In this way, stabilization or improvement of vision can be achieved.
Keratoconus – frequency and age
The frequency of keratoconus cannot be precisely quantified. The figures vary considerably in the literature. There is a wide range, as the following figure shows: experts estimate that around 4 to 600 out of 100,000 people suffer from keratoconus. This is due to the fact that the severity of keratoconus can vary greatly from person to person and the number of cases in the population varies greatly depending on the definition of manifest keratoconus. The eye disease usually begins in younger people between the ages of 10 and 20. However, it can also occur at an earlier or later age. Keratoconus affects both sexes.
Keratoconus: Causes are unknown
The causes of keratoconus have not yet been sufficiently clarified. It is unclear why the cornea becomes thinner and thinner, becomes deformed and gradually forms a cone. Hereditary and environmental factors are probably jointly involved.
In addition, some risk factors probably increase the risk of keratoconus. These include, for example:
Keratoconus in the family
Regular and severe eye rubbing
Allergic diseases, e.g. hay fever, bronchial asthma, neurodermatitis
Other underlying diseases, e.g. trisomy 21 (Down syndrome), Ehlers-Danlos syndrome and Marfan syndrome (diseases of the connective tissue)
Symptoms: Keratoconus impairs vision
Keratoconus usually begins in one eye and later affects the other. One eye is then often more severely affected. Keratoconus can cause various symptoms that primarily affect the ability to see. Because the eye disease develops slowly and insidiously, the symptoms also change as the disease progresses.
This is how keratoconus can become noticeable:
Affected people have blurred or distorted vision. Some see double or multiple images. Vision is particularly impaired at dusk and in the dark.
Increased sensitivity to light and glare – this can lead to problems when driving at night because the headlights dazzle.
Sudden deterioration in vision – some people can only see as if through a fog.
Visual acuity decreases or fluctuates: those affected have to change their glasses or contact lenses more often in order to see better again.
Acute keratoconus: symptoms
Some develop acute keratoconus during the course of the eye disease. Due to the permanent stretching, the innermost layers of the cornea tear open. Aqueous humor can enter through these cracks. The cornea then swells quickly and becomes cloudy.
These symptoms indicate acute keratoconus:
Sudden deterioration in vision.
Eye pain
The eyes water and are increasingly sensitive to light.
Acute keratoconus is an emergency that ophthalmologists must treat promptly.
Keratoconus: Diagnosis by the doctor
Sometimes ophthalmologists discover keratoconus by chance when patients come to the practice for another reason. For example, some people believe that their glasses prescription is no longer correct or that their contact lenses are no longer sufficient.
The diagnosis of keratoconus begins with a discussion of your medical history (anamnesis). The eye specialist (ophthalmologist) will ask you a few questions in order to gain initial clues. Examples are:
What exactly are your symptoms?
When did you first notice them and how intense are they?
Do the symptoms affect one or both eyes?
Have the symptoms worsened continuously or do they fluctuate in between?
Do you have a family history of keratoconus?
Do you suffer from any illnesses, such as an eye disease or allergy?
This is followed by various eye examinations. It is also important to rule out other eye diseases that cause similar symptoms. The most important are:
Slit lamp examination: The slit lamp is one of the most important diagnostic instruments for ophthalmologists. It consists of a powerful light source and a microscope, i.e. a “light microscope”. This allows the eye to be enlarged and displayed in detail. This enables the ophthalmologist to detect changes.
Refraction test: Ophthalmologists determine visual acuity and can detect vision problems. The patient looks through a device with different lenses (phoropter).
Corneal tomography: The doctor takes images of the cornea and creates a detailed map of how the cornea is shaped. Corneal tomography also allows conclusions to be drawn about the thickness of the cornea. It is suitable for detecting the first signs of keratoconus when the disease cannot yet be diagnosed with the slit lamp examination.
Ist der Keratokonus weiter fortgeschritten, lässt sich die kegelförmige Vorwölbung oft schon mit blossem Auge erkennen.
Wenn eine Patientin oder ein Patient nach unten sieht, verformt sich die untere Augenlidkante durch den Hornhautkegel – sie bildet optisch ein „V“.
Keratoconus: Prevention, early detection, prognosis
The causes of keratoconus are still largely unknown. Therefore, you cannot really prevent the eye disease. Some researchers suspect that genetic factors are involved, and you have no influence on these either. Increased eye rubbing is considered a risk factor. You should not strain your eyes mechanically or in any other way.
Special measures for early detection are also not known. The general advice is therefore: always consult your ophthalmologist if your vision deteriorates or you have other problems with your eyes. He or she can find out what is behind the complaints.
Progression and prognosis of keratoconus
Keratoconus usually develops slowly and progresses over time. Without treatment, the cone-shaped protrusion of the cornea becomes more and more pronounced. Initially, ophthalmologists can often correct the visual impairment with the help of contact lenses and slow down the progression. In the later stages, surgery helps to restore vision.
Keratoconus: Treatment depends on the stage
The treatment depends on the severity of the keratoconus. The speed at which the eye disease progresses also plays a role. The various treatment options have two aims: to improve vision and to slow down progression.
