Keratoconus: Causes and treatment (Keraring)

What is keratoconus?

Keratoconus is a non-inflammatory, often progressive, corneal disease that usually affects both eyes and causes thinning and bulging of the cornea. 

The cornea is the outer transparent layer of the eye. In addition to its protective function, the cornea takes on a major part of the refraction of light to focus the image. A healthy cornea is therefore one of the most important prerequisites for sharp and clear vision. 

The corneal changes associated with keratoconus result in blurred, blurred vision and double vision. Everyday life is usually severely impaired, such as driving a car, working on the computer, watching TV or reading.

What is the cause of keratoconus?

The cause of keratoconus is still unclear. Keratoconus is now believed to be caused by a variety of factors, with genetics appearing to play a particularly common role. Environmental influences can also promote the development of keratoconus.

Keratoconus is associated with:

  • Prolonged exposure to the cornea, such as excessive eye rubbing or long-term wearing of hard contact lenses
  • Various eye diseases, e.g. vernal keratoconjunctivitis
  • Systemic diseases such as Down’s syndrome

New examination methods enable early diagnosis, so that keratoconus is now recognized more frequently than in the past.

Symptoms of Keratoconus

The symptoms usually have their onset in late puberty to young adulthood. An earlier or later first occurrence is possible and known. 

Keratoconus usually affects both eyes, but symptoms can be different in each eye. While one eye has long been diagnosed with keratoconus, it can take years for the other eye to develop symptoms.

Symptoms include:

  • Blurred and distorted vision
  • Contact lens intolerance in advanced form
  • Seeing double vision
  • Increased glare sensitivity
  • Poor vision in twilight and darkness
  • Slight eye irritation

As keratoconus progresses, visual acuity continues to decrease due to the development of increased and irregular astigmatism.

Diagnosis of Keratoconus

The patient history plays an important role in the diagnosis of keratoconus. Initial information from the patient about diseases that are usually associated with keratoconus could be a first indication. Even patients who report that glasses/contact lenses have failed to correct the visual defect can give the doctor initial indications of the corneal disease that is present, since the visual defect can no longer be fully corrected with visual aids in advanced keratoconus. 

Keratoconus can be diagnosed in the early stages with a corneal topography. Corneal topography is a method for micro precise measurement of the cornea. This examination creates a colored relief of the cornea within a few seconds. The keratoconus shows typical bulging patterns in these images and can thus be clearly identified. 

In the advanced stage, keratoconus can already be diagnosed using the slit lamp microscope.

Treatment options for Keratoconus

The treatment options for keratoconus depend on the severity of the symptoms.


During the early stages, keratoconus can be corrected with eyeglasses. As the disease progresses, the glasses can no longer correct the visual defect.

Rigid (hard) contact lenses and scleral lenses

Dimensionally stable contact lenses can compensate for the irregularities of the corneal surface in advanced keratoconus through their shape and better vision is achieved than with glasses. Contact lens correction is possible as long as it is tolerated and the vision achieved is sufficient. 

Scleral lenses are also recommended for eyes with irregular corneas such as keratoconus. Due to its large diameter (15-18mm), the diseased cornea can be completely bridged.

Corneal Collagen Crosslinking (CXL)

Cornea collagen crosslinking is a promising method to slow or even stop the progression of keratoconus. 

In crosslinking, the cornea is irradiated with UV-A light (370nm) after the application of riboflavin (vitamin B2). The oxygen radicals released from the riboflavin during the irradiation react with the corneal collagen to form new cross-links. The cornea is thus strengthened. 

Crosslinking usually does not promise an improvement in visual acuity, so contact lenses are still necessary. 

Crosslinking should be done at a young age (<30 years) because keratoconus is not that advanced then. The corneal thickness should also be more than 400 microns.

Excimer laser after crosslinking

If the keratoconus is stable, a topography-guided PRK (photorefractive keratectomy) may be performed a few months after crosslinking to improve vision. 

The PRK method has been a scientifically recognized method for correcting ametropia since 1995. Treatment with the topography-guided eye laser treatment uses the measurement results of the cornea topographer to control the laser ablation in such a way that individual irregularities on the cornea (e.g. scars) are eliminated. 

INTACS (intracorneal rings)

Non-progressive keratoconus can be treated with so-called INTACS. These are thin, semi-circular, rings of plastic material that are implanted in the middle layer of the HH (stroma). After implantation of the rings, the cornea flattens and the position of the cone is changed in addition to the shape of the cornea. The cornea is strengthened by this procedure to eliminate some or all of the irregularities caused by keratoconus to improve the patient’s visual acuity Depending on the severity of the keratoconus, contact lenses or glasses may be required after the implantation.

The corneal thickness should be at least 450 micrometers and no corneal scars.

Phakic lens implantation (toric IOL)

In addition to topography-guided PRK, CARE Vision offers phakic lens implantation (IOL). The specialist places an additional toric artificial lens in the eye, which compensates for the curvature of the cornea in keratoconus and improves vision. The body’s own lens remains intact.


In certain cases, the doctor can combine different treatments simultaneously or consecutively. For example, after collagen crosslinking, a toric ICL can be used later to correct the patient’s ametropia. 

You can find out which treatment options are available during a visit to a preliminary medical examination at a CARE Vision location.

Frequently asked questions about Keratoconus (FAQ)

What is keratoconus?

Keratoconus is a non-inflammatory, often progressive disease affecting both eyes, in which the cornea becomes progressively thinner and more bulging. In the early stages, it is often mistaken for astigmatism.

Is keratoconus curable?

No, but the limitation of vision can be alleviated by various methods.

Is it possible to go blind with keratoconus?

Keratoconus does not cause blindness, but it can severely reduce vision. There may be distorted, blurred and double vision, as well as contact lens intolerance and increased sensitivity to glare.

What are the options for treatment?

Initially, glasses, contact lenses, and scleral lenses can be used to counteract the effect. In the further course, there are various treatment options, such as crosslinking of the cornea or kerar rings (corneal ring segments).

What happens if keratoconus is not treated?

The course is very individual and not predictable. The disease progresses differently in both eyes. In some cases, the keratoconus stagnates at some point. However, the cornea can also deform to such an extent that tears appear in the posterior cornea. Fluid can penetrate through these and cloud the lens.

How much does the keratoconus surgery cost?

How much a treatment costs depends on the treatment method. You can find out during a preliminary medical examination.

Are the costs reimbursed by the health insurance?

Reimbursement depends on the individual case and the health insurance company.