What is keratoconus?

Keratoconus refers to progressive thinning and bulging of the cornea which is associated with unstable and declining visual acuity. Keratoconus is also one of the most frequent reasons for a corneal transplant. The earlier it is detected and stabilized, the greater the possibility to avoid this.

„Most of our keratoconus patients first come to us because they want to have a life without glasses.”

Dr. Breyer

Unfortunately, the disease still remains undetected much too frequently. However, within the scope of our thorough preliminary examinations in which we also measure the cornea's structure with a Pentacam HR, we are able to identify the typical bulging even at an early stage. We have more than 13 years of experience in keratoconus therapy and recommend that a stabilizing therapy is initiated as early as possible.

What does keratoconus mean?

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Keratoconus Introduction

The keratoconus eye disease is a non-inflammatory disease of the eye's cornea in which it thins and increasingly bulges outwards until it assumes a conical shape. The bulging frequently occurs in the lower part of the eye. Approx. one in 2000 people is affected, usually time-delayed in both eyes. In most cases, keratoconus occurs in the second to third decade of a person's life and comes to a standstill between the fourth or fifth decade. However, in some patients, the progressive type of keratoconus not only makes wearing special contact lenses impossible but also necessitates a corneal transplant. In its initial stage, this rare eye disease is frequently confused with astigmatism and is treated incorrectly. Only experienced doctors are able to diagnose keratoconus with certainty by examining the corneal surface and back (endothelium), measuring its thickness and possibly determining the number of cells in the endothelium.

What are the causes of the corneal disease keratoconus?

It is suspected that a keratoconus is a malfunction between the collagen molecules of the connective tissue support structure of the cornea, causing reduced linking of the collagen and thus reduced biomechanical stability of the cornea. The causes are complex and have not been definitely established. The possibility of a genetic predisposition is supported by the fact that it often occurs frequently in families. Immunological factors may also play a role. However, so far, the only thing certain is that violent and frequent rubbing of the eye over the years, for example in people with allergies, is a high risk factor for development of a keratoconus. Thyroid dysfunction may also be a cause.

Studies have proven: UV Riboflavin crosslinking seems to be able to stop the increasing bulging of the cornea.

This is why we are recommending an examination of their thyroid gland to our keratoconus patients so that they can receive therapy with thyroid hormones if required. The thyroid hormone thyroxin seems to have significant influence on the cornea's biomechanics: It enhances the increase and stiffness of corneal tissue and affects the composition and characteristics of the collagen protein linking.

Due to progression of the keratoconus, the cornea increasingly bulges outwards and forwards. A distinction is made between the "silent" form of keratoconus, referred to as "forme fruste", and the so-called progressive keratoconus.

Young woman with glasses leaning at a wall and smiling.

At first, I was told I had astigmatism. But then it turned out that I had keratoconus.

Your spezialist for this topic

Portraitfoto von Dr. Detlev Breyer

Dr. Detlev Breyer

Ophthalmologist, eye surgeon and lead surgeon

Dr. Detlev Breyer specialized in the treatment of keratononus. Since 2006 he performs standard UV Riboflavin Crosslinking, since 2017 he recommends iontophoresis-assisted epithelial-on corneal crosslinking (I-CXL) because it is gentler for the patients.

What are the symptoms of keratoconus?

Possible consequences of keratoconus are abnormal fluctuations and reduction of visual acuity, irregular astigmatism, seeing halos around lighting sources, increased sensitivity to light and glares. If the disease stops at a stage in which the full conus shape has not developed yet, it is referred to as "forme fruste keratoconus". However, in 20% of patients, a progressive keratoconus develops which continues its progression swiftly. This can cause tears in the posterior cornea through which fluid from the anterior chamber gains access to the cornea, clouding it. This is called an acute keratoconus. At a late stage, a corneal transplant is frequently the only option.

Forme Fruste

Regarding its symptoms, forme fruste cannot be distinguished from normal astigmatism and is discovered accidentally during a detailed ophthalmologic check-up in frequent cases. It can be corrected with glasses or contact lenses and does not have to be treated if it is stable but has to be monitored and checked regularly. Forme fruste is ten times as frequent as the progressive form.

The progressive form of keratoconus

The progressive form of keratoconus is aggressive and frequently becomes noticeable in the patient's teens already. The progressive bulging causes a curvature of the cornea called astigmatism. Due to this irregularity of the cornea, correction by glasses becomes increasingly difficult. Contact lenses are more suitable since they exert pressure on the cornea and are able to level out the most severe irregularities. If the disease has not progressed too far, good correction, even up to the maximum visual acuity, can be achieved by contact lenses.
However, if the cornea's bulging continues to increase, even hard contact lenses are less stable in the eye and may fall out. In addition, the cornea below the center becomes increasingly thinner and scarring occurs due to the progressive bulging which makes the visual acuity worsen irretrievably.

A promising treatment is UV Riboflavin crosslinking.

Studies show that UV Riboflavin crosslinking can stop progressive bulging since it stabilizes the tissue. For this reason, Dr. Breyer and other keratoconus experts recommend performing this treatment as early as possible. The alternative to crosslinking is a corneal transplant.

Keratoconus and corneal ectasia

Keratoconus is a specific form of corneal ectasia. Ectasia is a medical term. It refers to bulging of a hollow space. Such a corneal ectasia can also occur after LASIK treatment. It is suspected that the flap incision weakens the cornea and bulging of the cornea occurs due to insufficient stability.

The stages of keratoconus according to the Krumeich classification

The keratoconus disease is classified in four stages in which the corneal bulging and the associated vision problems increase continuously. The first classification was made according to the Amsler classification and was expanded by Muckenhirn. Dr. Krumeich who is co-operating with our practice has developed this staging classification further.

The stage is determined by one of the respective characteristics being met. Corneal thickness refers to the thinnest measured point of the cornea. 1 dpt = diopters 2 µm = micrometers.

  • Eccentric steepening of the cornea
  • Induced myopia and/or astigmatism of ≤ 5 d
  • Corneal radiuses ≤ 48 d
  • Vogt's striae, no scars
  • Induced myopia and/or astigmatism of > 5 d to ≤ 8 d
  • Corneal radiuses ≤ 53 d
  • No central corneal scars
  • Corneal thickness ≥ 400 µm
  • Induced myopia and/or astigmatism of > 8 d to ≤ 10 d
  • Corneal radiuses > 53 d
  • No central corneal scars
  • Corneal thickness 200-400 µm
  • Refraction not measurable
  • Corneal radiuses > 55 d
  • Central scars
  • Corneal thickness ≤ 400 µm