Keratoconus

The eye disease Keratoconus refers to the progressive thinning and cone-shaped deformation of the cornea of the eye (cornea ). The disease usually begins on one side, the other eye is also affected in the medium term rule. The disease can be relapsing and usually affects only the central cornea. Men are affected twice as often as women.

In general, the affected are short-sighted. However, this short-sightedness can not be fully corrected with glasses, because the conical Hornhautvorwölbung caused an irregular curvature of the cornea (astigmatism ).

• 4.1 ( disease detection ) Diagnosis
• 4.2 Methods
• 4.3 correction 4.3.1 glasses
• 4.3.2 Soft contact lenses, piggyback system
• 4.3.3 Hard rigid contact lenses, hybrid lenses
• 4.3.4 scleral
• 4.3.5 Special lens
• 4.3.6 keratoplasty ( transplantation)
• 4.3.7 alternatives

• 6.1 everyday

Symptoms

The first signs are common eyeglasses with corrections change the axis and changing eyesight and an increasing corneal curvature, often initially in one eye. Since this is a rare disease, the symptoms in the early stages are often not associated with this eye disease. Most patients have a year long exchange of different ophthalmologists behind, until they encounter one who recognizes the disease. In keratoconus see those affected, sometimes only in one eye, phenomena such as: " double vision of objects " ( monocular diplopia ), additional shadows on letters and objects, as well as streaks or star-shaped rays that seem to go out of light sources.

A reliable assessment of symptoms is possible only through an analysis of the corneal surface, the corneal surface, corneal thickness and possibly even a cell count determination in the early stages.

Other features are Hämosiderinringe ( Fleischer'sche rings ), known as Keratokonuslinien. Here occurs a yellow -brown to green-brown coloration that as a half or closed circuit moves the base of the cone, visible in good lighting. During the further course of superficial, irregular scars and opacities may also like tears in the Descemet's membrane are visible and Vogt'sche lines occur.

In an advanced clinical picture keratoconus with the naked eye can see from the side. When it comes to a corneal edema ( fluid accumulation in the cornea ), there is an acute keratoconus. This may heal with scarring after three to four months.

Cause

The cause of keratoconus is still, in spite of extensive studies (eg long-term studies in the U.S. with 40,000 affected ), not known yet.

Rarely, it may cause cracks in the posterior cornea, so that liquid enters from the anterior chamber into the cornea, there is an acute keratoconus. This may lead to pain, but only here. This also manifests itself in a strong clouding of the cornea (you can see fog) and must be treated immediately in an eye clinic.

Evaluations of Keratokonushäufigkeit in radioactively contaminated areas in the Urals showed an increased incidence. Even researchers from other countries emphasize the increasing frequency in radioactively contaminated regions.

Course

The change of the corneal surface may be initially in small distinct keratoconus, are still often compensated with glasses. Some patients come a very long time along well with glasses. Some patients have at this stage also several pairs of glasses with different strengths and visual axes, which are supported partially in combination with contact lenses because eyesight and axis to change partly in the course of days.

With progression of keratoconus and stronger change in corneal refractive error usually associated with rigid contact lenses and in extreme cases with special lenses ( Keratokonuslinsen ) can be compensated. Most patients (about 80 %) get their lives with hard contact lenses along well and their vision is very good.

If there is no sufficient view can also be achieved with contact lenses because the cone is very advanced or the contact lenses can not be well adapted, the defective cornea can be replaced with a graft. But this only occurs in about 20 % of cases. The transplantation is performed in an eye clinic. There, the defective cornea is replaced with a donor cornea or rarely stabilized by other methods.

Upon further progress and a significant thinning of the entire cornea and sclera can be observed in very rare cases, this is referred to as Keratoglobus. The Keratoglobus occurs more frequently on both sides and is often pronounced differently in both eyes. As keratoconus " forme fruste " is called a cone shape, which does not develop to the full cone, but are still in the early stages.

There are often different diseases, including atopic dermatitis, Down's syndrome, Silver-Russell syndrome and Noonan syndrome associated with keratoconus. Atopy such as hay fever, eczema, allergic diseases, etc. are also included.

Under posticus Keratoconus is a curvature increase in posterior corneal understood, but at the same time the corneal surface remains intact. There seems to be a connection between keratoconus and keratoconus posticus to exist.

Stadiums

As early as 1950, Marc Amsler ( 1891-1968 ) divided the keratoconus in four stages. Here the extended table of Dieter Muckenhirn with the Hornhautexcentrizität that ( with keratometer ) came about since the Sagittalradienmessung.

1 CL = contact lens 2 HH = cornea

Cone stages after Krumeich

• Eccentric Hornhautversteilung
• Induced myopia and / or astigmatism of ≤ 5D1
• Corneal radii ≤ 48D
• Vogt lines, no scars

• Induced myopia and / or astigmatism of> 5D to ≤ 8D
• Corneal radii ≤ 53D
• No central corneal scars
• Corneal thickness ≥ 400 microns

• Induced myopia and / or astigmatism of> 8D to 10D ≤
• Corneal radii > 53D
• No central corneal scars
• Corneal thickness 200-400 microns

• Refraction can not be measured
• Corneal radii > 55D
• Central scar
• Corneal thickness ≤ 200 microns

1 D = diopters 2 microns = micrometers

Effects

• Distortions
• Double edges, multiple images
• Ghosting in vision
• Permanent eye redness
• Fatigue and tension of the facial muscles
• Strong inconvenience in dry, cold and stuffy air
• Extreme light and glare sensitivity
• Restricted View at night and at dusk
• Regular slipping or even loss of contact lenses
• Star when viewing individual light sources
• Schlieren while reading letter

Chance also dark circles have been associated with the disease. These side effects usually do not occur in all affected individuals. The observed phenomena are individual, just as the development of keratoconus follows no set rules and is different from eye to eye.

Epidemiology

In Germany is about 0.5 ‰ of the population, that is, each 2000. (Around 40,000 people) affected, but although this may vary by region and research methods. In most cases, this disease occurs between 20 and 30 years of age. However, it can also be felt from childhood age and up to the 40th or 50th year.

Comorbidities

Every second patient suffers more or less to a hypersensitivity. Examples are:

• Dry Eyes
• Dark Under Eye Circles
• Strong sensitivity to light
• Soft tissue rheumatism ( fibromyalgia)
• Skin problems ( eczema )
• Allergies ( house dust, pollen)
• Asthma

Tears quality is adversely affected by such second condition often and may be subject to additional changes by drugs.

Treatment

Diagnosis ( disease detection )

Diagnostic equipment are:

• Retinoscope, the oldest instrument in keratoconus is to see the typical " fish mouth " effect
• Ophthalmometer ( keratometer ) adjust for measuring the corneal curvature and contact lenses.
• Placido
• Slit lamp, also known as corneal microscope to detect the corneal layers and thickness
• Keratograf ( video keratometer ), for detecting the surface structure
• Pentacam ( Scheimpflug ) and OrbScan for detecting the topography of the front and back (endothelium ), and calculation of the thickness of the cornea
• Optical coherence tomography (OCT ) for receiving a cross-section of the anterior segment, corneal thickness and profile of the surface can be documented

Meanwhile, there are two forms of treatment, by which the progression of the disease can probably be stopped permanently in many affected:

Other treatments such as hormone therapy, E by vitamin D or vitamin complexes and locally employed cortisone showed no reliable results.

Correction

Glasses

One way to treat the glasses, which is usually used at the beginning of the disease. Some eye doctors are of the opinion this way is better than contact lenses because contact lenses may cause the keratoconus or at least amplify. However, a proof of this is lacking. Others report that treatment with hard contact lenses prevents further formation of the corneal cone. It will even lead to a flattening of the cone tips.

Helpful to be wearing a Pinhole glasses with small holes in the lens. By this grid point of the incident light beam is focused and aligned before the eye. A cure or reverse development of keratoconus but that is not to reach a scientific proof of the effectiveness of pinhole glasses do not exist.

Soft contact lenses, piggyback system

In some cases of incompatibilities in comfort with rigid contact lenses today can use special soft keratoconus contact lenses or soft, highly oxygen- permeable contact lenses and lens carrier (protective lenses ), under the hard contact lens be worn ( piggyback system).

Hard rigid contact lenses, hybrid lenses

Hard rigid contact lenses are usually used when no adequate correction of eyesight more can be achieved with glasses or soft lenses, or due to corneal deformation multiple images are seen.

The stronger called the tip of the cornea, Apex, bulging with time, more attention must be arched and the contact lens, because the Apexspitze may not experience any pressure. In this advanced stage special Keratokonuslinsen be customized. These usually have to have a quadrant- specific form to have a good and stable fit on the eye.

If the cone is very far advanced, however, can degrade the image quality and the patient concerned does not reach a hundred percent visual acuity more. Verspitzt to the cone on, a point is eventually reached at which the normal rigid contact lens is not a more effective treatment. Be it that they find no more support or is unable to achieve more visual acuity improvement or it comes to pressure points of the lens on the cornea. This is partly painful for the wearer, on the other hand also be dangerous, since the cornea is already diluted because of keratoconus and may experience additional stress damage.

Then a corneal transplant has to be considered. This occurs, however, only in about 20 % of all cases. Most patients get their lives along well with contact lenses.

Another option are the so-called hard - soft hybrid contact lenses; they consist of a hard rigid oxygen permeable core and a soft shell. This increase comfort and reduce irritation and intolerance, which are often caused by the small GP lenses. The loss of a lens directly from the eye is less likely.

Scleral

Scleral lenses are dimensionally stable, highly gas permeable contact lenses for visual treatment of keratoconus, which came to the fore again in the past 10 years. New, high gas permeable materials allow a healthy supply of the eyes with large lenses. The scleral lens is not different from the regular rigid contact lens on the cornea, but to the sclera, the sclera of the eye. The relatively thick tear film between the lens and the corneal surface compensates the irregularities of the eye and provides a relatively good visual performance.

The comfort of the scleral lenses is equated with the soft lenses because the lenses are much larger, move less on the eye and do not touch the sensitive cornea. Also no foreign objects or dust can get under the lens.

With scleral lenses is at a distinct keratoconus often a better visual acuity compared with small corneal contact lenses to achieve. The curved lens surfaces and the most powerful movement in small hard lenses often produce strong optical aberrations and an inconstant vision. Due to the small motion, the constant thickness of the tear film between the eye and the lens and the radii of curvature flatter Skerallinse creates an ideal optical system, and a clearer vision.

Special lens

Janus lenses have a stable core and a soft exterior. Since the production of these lenses is very expensive, they have never been able to properly enforce. This type of lens is little gas permeable, so the cornea is not sufficiently supplied with oxygen. Therefore, these lenses should be used only in special cases.

In rare cases ( with high sensitivity or a greatly increased sensitivity to dust) is also a " piggyback " system in question, in which a soft lens a hard contact lens is adjusted.

For patients with an intolerance, or who have problems in a dusty environment, there is a new supply option with HYDROCONE contact lenses ( soft lenses keratoconus ) to increase visual performance and comfort.

If also dimensionally stable Keratokonuslinsen sufficient visual acuity can be achieved or can not be tolerated, even scleral or Minisklerallinsen can be customized. These cover the entire cornea and rest on the leather skin.

Keratoplasty ( transplantation)

It is possible that contact lenses are not tolerated, for example, if the eye does not produce enough tears. Then, surgery has to be considered in spite of possibly better correction. Otherwise, a transplant is only carried out if adequate visual acuity with contact lenses no longer reached (visual acuity less than 0.3 ).

In a keratoplasty, the cornea is cut out, leaving only a small margin left ( trepanation ). The cut piece is replaced by donor tissue and sutured watertight by a double seam. The University Eye Clinic Heidelberg is the first in Germany a new laser device for corneal transplantation, which may be waived in the future on the seams. There is a lamellar ( layered ) and a penetrating keratoplasty ( sweeping ) keratoplasty.

The aim must always be to get your own cornea as long as possible. Because of the healing process after a transplant can last up to two years and even after a transplant approximately 85-90 % of those affected must again bear dimensionally stable, mostly special contact lenses. From a hasty keratoplasty is not recommended, may also help listed below alternatives further. These are usually but relatively new or there are no long-term studies. At which stages a method as a guide only, the treating physician may, however, are the best judge when the type can help.

Alternatives

In addition to these methods, there are others, but these are not elaborated here:

• Intra corneal ring ( ICR)
• Verisyse ( Artisan ) lens
• Laser The refractive epikeratophakia (EPI ) is applied in stage II and III
• Keraform treatment
• Conditioned with an excimer laser.
• Femtosecond LASIK with a femtosecond laser (intra Lense ). It depends, as can occur as a complication of a keratoconus

• Penetrating keratoplasty in stage IV
• Deep anterior lamellar keratoplasty ( DALK ) engl. "Deep anterior lamellar keratoplasty " ( DALK ) in advanced keratoconus

• Mini asymmetric radial keratotomy (MARK), designed by Marco Abbondanza. Stage I and II
• Radial keratotomy asymmetric ( ARK), applied by Professor Lombardi. Although this treatment is applied Lombardi since 1980, there is still no scientific studies.

A laser treatment (PRK, LASIK) is contraindicated.

Treatment Failure

Keratoconus is a rare disease, and so the expertise of ophthalmologists, eye clinics and a few specialized Opticians (esp. contactology ) will be limited in the future. For this reason, the keratoconus among those affected is often diagnosed only after years or misinterpreted (eg as a psychological or neurological disorder), since, for example optician optical phenomena can not understand without knowledge in this area of keratoconus sufferers.

The most common treatment error consists in prescribing "normal" (hard) or soft contact lenses. Keratoconus should be treated as early as possible with special high gas permeable lenses keratoconus or " networking".

Affected are even referred in some cases to a neurologist or psychologist, ophthalmologist or optometrist if the disease initially overlooked because of their rarity.

It may also happen that a pelluzide edge degeneration is mistaken for a keratoconus. There are differences in the essential details and treatment.

Prophylaxis (prevention)

After all, what is known so far, you can not actively protect against keratoconus, as the disease probably has at least a genetic predisposition as an additional cause.

Generally, it is certainly advisable to avoid anything that seems like a lot of eye strain and the cornea. This is particularly the " rubbing of the eyes ", which probably is due to too few tears or frequent computer work. Staying in rooms with dusty, smoky air or air from air conditioning systems is perceived by many stakeholders as a burden.

It is advantageous in any case, much to drink, to move in the fresh air and to avoid smoky or dusty environment.

Many therapists to use and sufferers are also of the opinion that the wearing of contact lenses is a very heavy burden on the cornea of the eye and as far as possible should be avoided. It is still not confirmed by studies that wearing contact lenses promotes keratoconus.

Expenses ( specific for Germany )

Since the health care reform of 2004, a reimbursement for contact lenses on the part of health insurance has proven difficult. It is particularly difficult to get a reimbursement of the cost in the initial stage, when Keratokonuslinsen be adjusted is. Many of the above alternatives are not paid, because here are usually no long-term studies or surgical methods are controversial.

The current (2013 ) Tools directory of the Statutory Health Insurance Funds Association leads, among others, in the category " Optical corrective lenses special " so-called Keratokonuslinsen ( individual production ) whose costs are covered up to an agreed fixed amount under an appropriate medical indication.

Forecast

A forecast for the keratoconus is not possible because neither the causes of the disease nor the environmental impacts are adequately studied on the course.

In some individuals a transplant waiting only a short time, for example in weeks or months after the first occurrence of the disease, it is necessary others come decades or permanently with glasses or contact lenses cope.

The only observation that is generally confirmed by patients and clinicians, is the experience that a keratoconus frequently begins between 15 and 20 years of age and often comes to a stop between the ages of 40 and 50 years of age.

Problems

Everyday life

A big problem is that always go back lenses and bought later lost or must be sought from the health insurance companies. It is also common for About Eye irritation ( redness, excessive tearing, etc.) then only helps the removal of contact lenses. Whether an impairment of passing vehicle is present, the ophthalmologist must clarify.

Visual acuity can fluctuate several times a day. Through these altered visual conditions may cause deterioration in thinking, memory and concentration processes.

Since the keratoconus and its features are still relatively unknown in the population, it may occur declaration needs ( Why do you wear contact lenses and no glasses Why we see today bad and tomorrow well, why can not work it just because the contact lens lost is? ... )