Keratoconus is characterised by an excessive curvature and pointy, cone-shaped deformation of the surface of the cornea, commonly affecting both eyes. On average, every 2000^th person suffers from this disease, where a familial predisposition is not seldom. In most cases, keratoconus appears in young adulthood and shows a pronounced likelihood to progress until the age of 30. Some cases however, appear to be self-limiting, stabilising the corneal surface. The younger the affected person is at the time of the diagnosis, the more likely the person is to have a progressive case of keratoconus. The cause of keratoconus has not yet been fully explained, although an imbalance in the corneal metabolism and a lack of cross linking of the corneal lamellae are assumed to be the causes.

How is keratoconus recognisable?

A decrease in visual acuity and an ever-changing glasses or contact lens prescription  (through the irregular and abnormal corneal curvature) are early signs for such a pointy, cone-shaped corneal bulging. In pronounced cases, the deformation of the corneal surface can be clearly seen by the sideways lighting of the affected eye or by the pointy deformation of the lower eyelid as seen by looking from above the patient’s eye, while he or she is looking downward.

Easy methods, as described above, as well as obtaining the patient’s exact medical history and conducting an exact examination with optical equipment can confirm the keratoconus diagnosis. A measurement of the cornea by means of corneal topography can make the exact gradation of the curvature visible. The eye doctor can use a slit lamp to determine a pronounced progression of keratoconus as well as a clouding of the mid-corneal layer and typical keratoconus lines (Vogt lines) as signs of a reduced corneal thickness. The measurement of the corneal thickness (usually 500 μm) is conducted through pachymetry. 

What is the prognosis for keratoconus?

In the beginning stages keratoconus is easy to correct with glasses or simple contact lenses, however with further progression these methods are unsatisfactory. Hard, specially made contacts are the only conservative treatment which can enable good visual acuity in cases of keratoconus. Of course in most cases of progressive keratoconus there is an intolerance of the keratoconus lenses. Because the cornea gains thickness at the steepest point, the surface covering layer (epithelium) can exceed its individual limits and even burst. This so-called “acute keratoconus” leads to a sudden swelling of the cornea and its clouding, and the affected patient has blurry vision, suffers from heightened glare sensitivity and tearing, and also has severe pain. In such cases,  transplant is mandatory, after conservative treatment of the clinical picture.

For a short time, a new form of treatment called cross linking has been available to keratoconus patients. At present this treatment is being offered internationally, within the scope of clinical studies. The goal of this operation is to mechanically stabilise the fibres of the cornea, thereby preventing a further change of the corneal surface. The actual stabilisation occurs after the ablation of the surface layer of the cornea (epithelium) and the repeated pre-treatment of the cornea with vitamin B2. Through this pre-treatment, the UV light is “caught”, so to speak, in the corneal tissue in order to achieve the desired results and not to end up in deeper layers of the eye which would be damaging. The following radiation of the cornea with UV light of a certain wavelength serves to connect the corneal fibres, thereby contributing to a targeted stabilisation of the corneal fibres. The partially ablated corneal epithelium is postoperatively replaced by a bandage type of contact lens and completely regenerates by itself within the first days after cross linking. Years of research and successful clinical studies have been able to confirm that the advancement of keratoconus in 80% of cases was stopped. Thanks to this new operative technique, the necessity of corneal transplant has been slowed or even completely prevented for numerous patients.

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