What is keratoconus and what are its symptoms? + Diagnosis and treatment - diseases

Keratoconus is a non-infectious degenerative disease of the cornea. The cornea arches asymmetrically and conically, resulting in impaired vision to blindness. 

In most cases, this disease is confused with myopia or astigmatism. Because in the beginning, he has the same symptoms. It can develop completely unnoticed for many years, which worsens subsequent treatment.

It most often affects the cornea of ​​both eyes, in up to 85% of cases.  

It is said that the cause is congenital inferiority of corneal tissue, the exact reason of which has not yet been clarified. A genetic and partially hereditary basis is assumed.

It often occurs together with other diseases, such as allergies, atopic eczema, Down's, Turner's, or Marfan's syndrome.

Excessive eye contact in children also increases the risk of development. It arises in childhood and during puberty, 10 - 20 years of age. The sooner he starts, the faster he progresses - he progresses. After the age of 40, the overall progress is more modest.

The disease is rare and affects approximately 1 in 1,500 people.
It is more often diagnosed in young men.
Therefore, it is often referred to as a disease of young people.

The cornea is an important part of the optical system of the eye. When it is disturbed, a visual impairment occurs. It has a regular domed curved shape, while the keratoconus causes its asymmetrical conical arching and thinning of the thickness.

Vision gradually deteriorates during keratoconus, and the disorder is very poorly corrected. In the worst cases, blurred vision, swelling, and rupture of the cornea occur. In this case, the only solution is a corneal transplant.

What is the cornea?

The cornea, professionally the cornea (cornea), is, together with the whites of the eyes, the sclera, the tight envelope of the eye. The cornea has differently arranged fibers than white, which guarantees its transparency.

The cornea makes up about 20% of the surface of the eye.

It is thus a transparent,  important, and first element of the optical system of the eye. Its total optical power is up to two-thirds, which is 43 diopters.

A healthy eye has an optical power of about 60 diopters.

It forms the first mechanical as well as chemical barrier between the outside world and the inside of the eye. From the eye, it is the most stressed part that resists external influences and is exposed to the risk of injury.

Corneal injury or injury causes sharp stabbing pain in the eye and increased tearing.

Inside the eye, it is surrounded by the ventricular fluid of the eye, and on the outside, a tear film urges it. For more information on the tear film, see the article on dry eye.

It does not contain any vessels, but a number of nerve endings. These give it sensitivity to touch, changes in temperature, and chemical properties. The eyelids close reflexively when in contact with the cornea.

The cornea is not even a millimeter thick. Its outer part (towards the circumference) has a thickness of 0.8 and the inner (towards the center) 0.6 mm. Its diameter is 12 mm.

Despite its small width, it consists of five layers.

5 layers of cornea :

1. epithelium
2. Bowman's membrane
3. tree
4. Descemet's membrane
5. endothelium

The table describes the 5 layers of the cornea

The cornea does not contain blood vessels. Blood supply is provided by the marginal layer. The rim is interwoven with blood vessels and is referred to as a limbus. 

Furthermore, nutrients are introduced into the cornea via ventricular fluid and tears.

Oxygen supply is provided from the outside environment. The most important role is played by the tear film, which urges the cornea. Its quality is therefore very important and dry eye syndrome is risky for eyesight.

The tear film and tears also have a defensive, cleansing function, preventing clouding and drying of the cornea. They also affect the optical properties.

The cornea is sensitive to injury and degenerative changes in terms of optical properties. In addition to keratoconus, it can be affected by other problems, such as:

• keratoglobus
• pleucidal marginal degeneration
• crocodile skin degeneration
• Cornea guttata
• lipid keratopathy
• zonal keratopathy
• epithelial and Bowman's membrane dystrophy
• and other

Keratoconus, keratoglobus and marginal pleucidal degeneration are classified as ectatic corneal degenerations.

The exact cause is not revealed even today. Keratoconus is a degenerative disease of the cornea and is characterized by arching but also thinning thickness. Which causes vision problems.

Both eyes are affected, but asymmetrically, ie one more.

Familial occurrence, and therefore hereditary, is assumed. The genetic factor plays a role.

It has been found that in most cases it occurs together with allergic diseases, such as atopic eczema, hay fever, but also with diseases such as Down's, Turner's, or Marfan's syndrome.

Civilization factors, such as stress and poor lifestyle, are also said to be involved in the outbreak. Mechanical stress, and thus poor wearing of contact lenses and frequent eye wiping in children, also have a negative effect.

As the onset of the disease is at a relatively young age, from the 10th to the 30th year of life, the symptoms also start early. The rule is that early occurrence is also characterized by a faster progression of difficulties, ie progression.

The initial symptoms appear mostly from the 13th to the 27th year.

The second group of people at risk is between the ages of 40 and 60. In this case, however, it does not have such a significant course.

Blurred vision is one of the first and most common symptoms. This is primarily compensated by diopters, ie glasses or lenses.

It is therefore very often confused with myopia or astigmatism.

This is a mistake, as delaying appropriate treatment complicates the overall condition.

An alarming indicator is if the eyesight deteriorates by one cylindrical diopter per year.

The manifestation is therefore a faster deterioration of vision. Myopia and astigmatism deepen.

Manifestations of keratoconus are difficulties such as:

• visual acuity impairment
  • exacerbation of myopia (minus diopters)
  • and astigmatism (cylindrical diopters)
  • bad correction of visual impairment
  • rapid progression and deterioration even with diopters per year
• image distortion
• blur or distort the image
• double vision
• driving or reading is also a problem
• duplication, ie duplication of the observed object
• reduction of tolerance for wearing contact lenses
• unnatural tilting of the head to the side
• advanced  corneal opacity 
  • and thus a reduction in transparency
  • up to the loss of vision, ie blindness
  • lightness
  • hydrops, swelling, corneas
  • it causes pain

Keratoconus is a chronic disease. The anamnesis is important, but especially a special professional eye examination.

The eye examination also includes the evaluation of the visa, ie visual acuity using an optotype. An objective refraction is evaluated with an autorefractor. Subjective refraction is also evaluated.

Examination of the anterior segment of the eye includes an examination of the eyelids, conjunctiva,  tear film

The examination also takes place with the help of a slit lamp. Corneal topography is performed, a photograph of the anterior segment of the eye as aberrometry.

The most modern investigative devices include Galilei, Pentacam, and Orbscan.

The examination looks for signs such as:

1. Bowman's shadow - the cause is the scars of the cornea, the cornea gradually arches
2. Fleischer ring - yellow, brown, or gray coloration of the cornea is observed
3. Munson's sign - or even Munson's sign
   • at an advanced stage
   • when viewed below, the lower lid arches into a V-shape
4. Axenfeld's symptom when the arched part of the cornea is characterized by a loss of sensitivity to touch
5. Vogt striae - cracks of the Descemet membrane
6. keratoconus scarring - scars in the area of ​​the corneal arch
7. hydrops, ie swelling in the acute stage
   • as a result of rupture of the Descemet's membrane
   • sudden deterioration in visual acuity

The course of the disease is long, ie chronic. Typically, the sooner it starts, the faster it progresses, that is, progress and worsening difficulties.

The first symptoms are mild and often overlooked. Many people do not even know he has keratoconus. The most common is decreased visual acuity when the symptoms are confused with myopia or astigmatism.

This is a complication of subsequent and delayed treatment. Gradually, the difficulties develop and cause a significant deterioration in vision.

Neglected treatment can lead to corneal clouding, rupture, and blindness of the damaged eye.

In most cases, keratoconus is present in both eyes, with asymmetric progression. Simply described that one eye is affected more.

The disease can be alleviated with the help of state-of-the-art methods, but it still cannot be completely cured.