Keratoconus is a progressive thinning and deformation of the cornea of the eye (cornea). A cone-shaped protrusion of the cornea takes place. Keratoconus is often accompanied by other diseases and, in some cases, genetic disorders.
What is keratoconus?
Keratoconus is characterized by the cone-shaped deformation and thinning of the cornea of the eye. Both eyes are always affected. However, the severity of the deformation may be different in the two eyes. The disease usually begins in one eye. A little later it spreads to the other eye. Keratoconus is characterized by two important features. On the one hand, the cornea becomes thinner and more pointed, and on the other hand, visual acuity steadily decreases over time. Patients become nearsighted. Complete compensation with a visual aid is not possible. This is due to the irregular protrusion of the cornea. The corneal curvature is also called astigmatism. Keratoconus can progress in episodes. However, there are also cases with a smooth and continuous protrusion of the cornea. The disease is very rare. In the West, one in 1000 to 2000 people suffer from keratoconus. In Germany, about 40,000 people are affected. In the Middle East, however, the prevalence is somewhat higher. Mostly the disease starts between the age of 20 and 30. However, it can also occur much earlier (as early as childhood) or much later (between the ages of 40 and 50).
Causes
The causes of keratoconus are not fully known. For example, there is evidence that it occurs in association with certain genetic disorders such as Down syndrome, monosomy X, Ehlers-Danlos syndrome, or Marfan syndrome. However, the development of keratoconus has also been observed in the context of atopic eczema, hay fever or other allergic diseases. Structural examinations of the cornea have revealed changes. Thus, the arrangement of the individual collagen lamellae is probably destroyed by a proteolytic degradation process. Several causes may lead to this. Either genetic changes are present or the eye is affected by various external stresses such as severe rubbing or environmental factors. At least these factors act as an initial event. The eye pressure increases and the tissue weakness of the cornea continues to increase. As a result, the curvature of the cornea continues to increase. A cycle is set in motion that is very difficult to stop. The disease can become acute if there are tears in the posterior cornea. Fluid then enters the anterior chamber of the eye, resulting in rapid clouding of the cornea. In this case, patients only see as if through fog. However, this so-called hydrops regresses on its own.
Symptoms, complaints, and signs
Keratoconus begins insidiously. Those affected have to constantly adjust their glasses. They sometimes see things twice. At times, this may be in only one eye. Furthermore, shadows appear on objects and letters, as well as star-shaped rays and streaks from light sources. Keratoconus lines with yellow-brown or green-brown coloration appear, which surround the corneal cone completely or in a semicircle. Furthermore, there may be tears in Descemet’s membrane, which become visible as so-called Vogt’s lines. In advanced stages, acute keratoconus often develops, which is a water retention in the cornea. This heals after a few months with scarring. Keratoconus is divided into four stages, which document the extent of corneal thinning and curvature. Important symptoms of the disease are the occurrence of ghost images during vision, multiple images, distortions, constantly reddened eyes, tense facial muscles, intolerance to cold, dry or stuffy air, sensitivity to light, seeing halos, limited vision at night, changes in position or even falling out of contact lenses, star vision and streaks when reading. Allergies, asthma, rheumatism, atopic dermatitis, or dry eyes are frequently observed as concomitant conditions.
Diagnosis and course of the disease
Keratoconus often cannot be diagnosed until noticeable myopia has already developed. Sometimes the diagnosis is made during a routine examination by an ophthalmologist.Signs of the disease result from frequent fitting of glasses. However, the cause of these eye problems is often not recognized immediately because keratoconus is very rare. Diagnostic equipment available includes a skiascope, which can detect the well-known fishmouth effect in keratoconus. Furthermore, different devices are used to measure corneal radii, corneal layers or corneal thickness. In addition, the surface structure of the cornea is recorded and the cross-section of the anterior segment of the eye is taken.
Complications
As a rule, keratoconus causes discomfort to the eyes. In this case, the affected person mainly suffers from visual complaints and, in the worst case, can also go completely blind. Furthermore, the cornea is also damaged. The complaints considerably restrict the quality of life and the everyday life of the affected person. It is not uncommon for vision problems to lead to psychological upsets or depression. Young people in particular often suffer greatly from vision loss. In most cases, night blindness also occurs. Patients also suffer from increased sensitivity to light and are therefore restricted in their daily lives. Similarly, veil vision occurs. As a result, in some cases the affected person can no longer perform his or her professional activities, also because those usually have to deal with a reduction in concentration. In some cases, no direct treatment is necessary and the affected person can compensate for the discomfort with contact lenses. Furthermore, interventions with a laser can also be performed. In most cases, these only take place in adulthood. No particular complications occur and the life expectancy of the patient is not reduced by this disease.
When should one go to the doctor?
As a rule, a doctor should be consulted in any case of keratoconus. In the worst case, the disease can lead to the death of the affected person. Early diagnosis and treatment have a positive effect on the further course of the disease. A doctor should be consulted if the vision of the affected person changes frequently and worsens over time. Likewise, double vision or veil vision may indicate keratoconus and should be examined by a physician. In many cases, the affected person’s cornea turns green or yellow. The eyes are red and objects may appear distorted or deformed. If these symptoms are permanent and do not disappear on their own, a doctor should be consulted in any case. Furthermore, asthma can also indicate keratoconus. In case of this disease, an ophthalmologist should always be consulted. In acute emergencies, the affected person can turn to a hospital. The life expectancy of the patient is not negatively affected by the disease.
Treatment and therapy
Treatment of keratoconus consists of constant adjustment of glasses or insertion of contact lenses. There is still no consensus on the best method of treatment. Contact lenses can slip or even fall out if the cornea has already changed further. Some doctors therefore try to regulate the problems by permanent correction of the eyeglasses. According to not confirmed observations contact lenses should accelerate the curvature of the cornea. However, other physicians also report the opposite. So just the application of contact lenses is supposed to stop the curvature. Thus, many different contact lenses are used. In individual cases, corneal transplantation is also performed.
Outlook and prognosis
The daily life of affected individuals is often affected by symptoms, such as glare sensitivity, double vision, and rapidly changing visual acuity. The latter often happens within a few days, which means that correcting the visual acuity by means of glasses only leads to short-term success. To compensate for this, it helps to have glasses in stock in different visual acuities and to use them as needed. After consultation with the attending physician, there is also the option of combining contact lenses with the existing glasses and thus being able to react quickly and extremely flexibly to a change in vision. Due to the increased risk of infection in keratoconus, however, absolute hygiene and regular changing of contact lenses must be ensured. Changes within the home also allow a further increase in quality of life.To this end, possible sources of interference must be eliminated. Incorrectly installed lamps or excessively bright light sources cause unpleasant streaks in the field of vision for many patients or, due to the high sensitivity to light, an unpleasant glare. If these effects occur at the workplace, the patient should not be afraid to address this issue with his or her supervisor and work with him or her to develop a way to remedy the situation. Otherwise, the work capacity is sometimes significantly limited by a reduction in the ability to concentrate and can lead to an inability to work at this workplace.
Prevention
Since the exact causes of keratoconus are not known, no specific recommendations can be made for its prophylaxis. In general, however, those affected are advised to drink plenty of fluids and exercise frequently in the fresh air.
Aftercare
Aftercare for keratoconus is closely related to prevention. Among other things, sufferers should drink enough fluids and get out in the fresh air to take care of their eyes. The frequent changes in visual acuity can be mitigated in everyday life by eliminating sources of interference. To do this, it is helpful to adjust the working and living environment accordingly. Excessively bright light or unfavorable lighting intensifies the feeling of not being able to see properly. However, with better illumination, patients no longer feel as impaired. To compensate for varying visual acuity, it is also a good idea to use several pairs of glasses. In this way, patients find it easier to cope with their visual complaints. However, this requires precise consultation with the ophthalmologist. If necessary, the ophthalmologist can consult with an optometrist to find a satisfactory solution for the patient. He may even recommend the combination of glasses and contact lenses. Proper hygiene of the eyes is also very important. By taking the appropriate measures, patients can take care of their eyes and protect them from possible inflammation. Thus, negative effects of infections on vision can be avoided.
What you can do yourself
Patients with keratoconus suffer from the often rapidly varying visual acuity and various symptoms such as glare sensitivity and double vision, which may interfere with everyday life. In order to maintain their usual quality of life, patients first try to adapt their living environment to the disease and eliminate certain sources of interference. These include, for example, lamps fixed in an awkward position or simply too bright, which leave streaks in the field of vision of many patients with keratoconus and are also unsuitable due to their sensitivity to glare. Because visual acuity often changes in affected individuals within days, both in the direction of improvement and deterioration, owning multiple pairs of glasses makes it easier to manage the condition. Some individuals even combine contact lenses with glasses, although such practices should always be cleared with the treating ophthalmologist and, if necessary, additionally with the optometrist. In this way, patients are able to react flexibly to variable visual acuity. In addition, hygiene in the area of the eye plays a relevant role in preserving the health of the visual organs and thus the general well-being of the patients. By means of adequate hygienic measures, affected individuals protect their eyes from infections that may have a negative impact on the progression of keratoconus.
