Corneal diseases

Corneal diseases come in many variations and can affect all the different layers of the cornea.

Corneal diseases are often accompanied by the sensation of having a foreign body in the eye or increased glare, whereby the loss of transparency of the cornea can even lead to loss of vision.

A wide variety of forms of inflammation, eye injuries or age-related and congenital diseases can be responsible for this.

Symptoms

Causes

Diagnosis

Treatments

Aftercare

FAQs

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The cornea

The cornea is the transparent, crystal clear and translucent frontmost section of the eyeball and is located in front of the pupil. In a healthy condition, it is about half a millimetre thick. With its natural curvature, it contributes two-thirds of the refractive power of the eye, together with the lens.

The cornea is often referred to as the “protective screen” of the eye, as it is also responsible for protecting the eye against external aggressors. For this reason, diseases of the eye that affect the transparency or shape of the cornea can lead to serious visual impairments, which is why they require consultation with an ophthalmologist.

Symptoms

Anything that changes the cornea has a negative effect on vision, which is why a disease of the cornea eventually becomes noticeable with poor vision and increased glare sensitivity.

In the case of a cornea disease such as Fuchs’ dystrophy, the symptoms are worse after waking up and improve over the course of the day. In the case of dry eye, the exact opposite is true: Visual effort such as reading or computer work worsens the symptoms over the course of the day.

The eye disease keratoconus (i.e. the pathological, conical bulge of the cornea that can progress gradually) first becomes apparent through frequent changes in the strength of the glasses, whereby myopia can never be completely corrected. Double vision, and streaks and starburst rays may also appear in the vision. It is therefore important to pay particular attention to the following symptoms if a cornea disease is suspected:

Frequently changing glasses prescription strength
Milky, blurred vision
Fluctuating vision over the course of the day
Glare sensitivity
Redness and burning of the eye (gritty sensation)
Change in the surface of the cornea
Dry eye
Frequent need to rub the eyes

Causes

Causes of corneal disease include inflammatory processes of an infectious and non-infectious nature, degenerative and hereditary changes of the cornea. Injuries and changes as a result of medical treatment can also lead to corneal disease. The individual diseases of the cornea and their causes at a glance:

Corneal injuries ( corneal erosion): An erosion is the abrasion of the uppermost layer of cornea. This can be caused by superficial injuries (e.g. by a fingernail or a thin splinter) or by contact lenses worn for too long or which are badly fitting. The exposed nerve endings cause severe pain and lead to increased lacrimal flow, redness, light sensitivity and swelling of the eyelid. Vision may also be significantly impaired.
Inflammation of the cornea (known as keratitis): Inflammation of the cornea can occur as a result of external aggressors when pathogens enter the cornea. The symptoms are similar to those of an erosion (corneal injury) and are treated by eye drops, eye ointments and, if necessary, tablets. However, keratitis can also occur without an external injury, i.e. from the inside, as the result of other eye diseases, such as inflammation of the iris or as a consequence of general illnesses (especially rheumatism). This type of keratitis is not without its dangers, as pain and sensitivity to light are often lacking. The only symptom is usually the deterioration of vision. It is important to consult an ophthalmologist immediately if keratitis is suspected.
Corneal ulcers: A corneal ulcer is a sore on the cornea. It is usually caused by a lesion of the uppermost layer of the cornea through which pathogens can penetrate the cornea and destroy the tissue of the cornea. Two possible serious complications make corneal ulcers an absolute emergency, as they can lead to a perforation of the cornea and thus to a transmission of the pathogens to the inside of the eye, leading to the risk of blindness or even loss of the eye. Corneal ulcer is very often painful and is accompanied by redness, increased lacrimal flow, light sensitivity and eyelid spasm. Vision is usually significantly restricted.
Corneal scarring: Irrespective of whether scarring is caused by keratitis, an ulcer, deeper erosion or injuries, it can significantly impair vision.
Corneal degeneration: Corneal degeneration includes changes to the cornea that may occur as a result of ageing or after corneal diseases or injuries. As the cornea loses its transparency, vision is significantly reduced in some cases.
Corneal dystrophy: Corneal dystrophies are usually bilateral congenital changes of the cornea. These changes can occur in any layer of the cornea. Some do not cause visual impairment, but others, such as Fuchs’ dystrophy, can affect vision considerably.
Keratoconus (i.e. the pathological, conical bulge of the cornea that can progress gradually): This condition first becomes apparent through frequent changes in the strength of your glasses, although myopia can never be completely corrected. Double vision, and streaks and starburst rays may also appear in the vision.
Corneal grafting (keratoplasty): If conservative treatment attempts using eye drops fail to fade the scarring, it must be surgically removed.

Diagnosis

Using a variety of modern instruments for exact measurement of the cornea, it is possible to make an exact diagnosis of the respective corneal disease.

Slit-lamp examination: A slit lamp allows a thorough preliminary examination of the cornea. For example, the slit-lamp examination can provide initial indications of a possible corneal change.
Scheimpflug imaging: With the help of Scheimpflug imaging, cross-sectional images of the anterior segment of the eye can be generated at various levels, which in turn can then be used to create a 3D model of the entire cornea.
Corneal topography: Corneal topography is used where the patient has astigmatism, especially in the case of keratoconus, i.e. the pathological, conical bulge of the cornea. The extent of astigmatism can be measured by projecting rings onto the cornea. The surface topography – similar to a map – is shown in colour.

Measurement of corneal thickness (pachymetry): The thickness of the cornea provides information about the stability of the cornea.

Corneal microscopy (endothelial cell measurement): A high-resolution laser scan that makesa precise examination of the inner endothelial cells of the cornea possible. The corneal endothelium has the task of constantly pumping fluid out of the cornea and thus regulating its water content: The worse its function, the more the cornea swells and thickens.
Information on the curvature of the anterior cornea and data from pachymetry (measuring corneal thickness) alone are not sufficient for a corneal disease such as keratoconus to be detected at an early stage. For this reason, early detection of keratoconus via Belin/Ambrosio Enhanced Ectasia Display is based on a keratoconus index created using elevation data and corneal thickness.
Anterior segment OCT (optical coherence tomography): This examination method makes it possible to produce high-resolution images of the cornea. Anterior section OCT represents the individual layers of the cornea in detail and helps to assess corneal thickness and its changes at the depth of the cornea.

Treatments

The individual corneal diseases require different treatment methods. Specifically, these are:

Inflammation of the cornea: Inflammation of the eye is treated with eye drops, eye ointments and, if necessary, tablets.
Cornea injuries: Intensive treatment with eye drops or eye ointment or bandage contact lenses often helps to heal a corneal injury without scarring. However, if the injury does not heal despite treatment, an amniotic membrane covering may be necessary. The amniotic membrane is a tissue obtained from the placenta, which is sewn onto the open area of the cornea.
Corneal ulcers: A corneal ulcer is generally treated using eye drops or ointments and possibly tablets. However, if an ulcer does not heal, an amniotic membrane covering may also be necessary. If perforation occurs, it must be surgically sealed immediately. If the inflammation reaches the inside of the eye, surgical irrigation of the eye may also be necessary.
Corneal scarring: If drug therapy attempts using eye drops do not fade the scar, surgery must be considered, depending on the patient’s symptoms and impairment. In the case of superficial scars, the scar tissue can be removed by means therapeutic scraping of the corneal epithelium, i.e. the uppermost cell layer of the human cornea. In the case of deep scars, on the other hand, only corneal transplantation is promising.
Corneal degeneration: Corneal degeneration is treated by EDTA chelation. Under local anaesthesia, after removal of the uppermost layer of cornea, the calcium deposits in the cornea are removed using EDTA (ethylenediaminetetraacetic acid).
Corneal dystrophy: In early stages of this disease, vision improves over the course of the day, as water from the cornea surface can evaporate when the eye is open. In addition, special eye drops or eye ointments can be used to “draw water from the cornea.” However, it should be noted that this type of therapy can only delay the course of the disease, but not completely stop it.
Keratoconus: In early stages of the disease, patients often have the strength of their glasses and/or contact lens prescription frequently adjusted. However, as soon as the disease is more advanced and neither glasses nor contact lenses can provide an improvement, surgery or even a corneal transplant becomes necessary.
Corneal grafting: Keratoplasty is an operation of the cornea in which the cornea of a dead donor is transplanted. If the ophthalmologist has determined the need for a corneal transplant, suitable donor tissue is sought in a cornea bank. The actual operation is performed either under local anaesthesia or under general anaesthesia. Depending on the degree of clouding on the patient’s cornea, the ophthalmologist can either fully or partially remove it. They then cut the donor cornea to size and suture it to the patient’s eye. The sutures remain in the eye for several months to years, as wounds heal very slowly in this area.

Aftercare

In the event of corneal disease, regular check-ups with an ophthalmologist to check your eyesight, determine the strength of your glasses and measure the surface of the cornea are important and crucial.

FAQs

Can the cornea regenerate?

No, it can’t. For this very reason, degeneration processes, injuries, illnesses, infections or even genetic changes can lead to clouding or scarring of the cornea and impair vision and even lead to blindness.

What can be done about corneal diseases?

In mild cases of the disease, doctors can try to remove the clouding with medication, drops and ointments or by laser treatment; in severe cases, if the cornea has already become milky, only the transplantation of a healthy cornea can help. Regular check-ups are important for early detection

What happens with corneal topography?

Corneal topography is a modern, micro-precise examination method for measuring the cornea of the eye. In a few seconds, an ophthalmologist creates a coloured relief, a “map” of the cornea.