Corneal inflammation (Keratitis) – Causes, Symptoms and Treatment

In addition to participating in the visual process, the cornea has a protective function, which is to protect the eye from the penetration of foreign bodies or external stimuli such as smoke, allergens or liquids. The so-called corneal reflex therefore triggers the blinking of the eyelid when thermal, mechanical or chemical stimuli act on the eye. However, if the cornea is damaged despite its protective reflex, for example by a minor injury, pathogens such as viruses, bacteria or fungi can enter the eye and cause inflammation. However, corneal inflammation can just as easily be caused by mechanical stimuli, for example by a foreign body in the eye. Therefore, keratitis is medically differentiated into two types:

If the cause of the inflammation is an infection of the cornea with bacteria, viruses, fungi or parasites, it is called infectious keratitis. Bacteria such as staphylococci and streptococci are particularly common triggers. They are found on the skin and mucous membranes and can therefore be transferred to the eye particularly quickly with a finger.

Approx. 30% of all bacterial keratitides occur in contact lens wearers (especially soft contact lenses). 

Among the viruses, the herpes simplex virus is often the cause of the symptoms. These herpes viruses lie dormant in certain nerve cells in the body and can always lead to a re-onset of inflammation.

More rarely, keratitis is triggered by fungi or parasites.

A pathogen is not always the cause. A foreign body, for example, can also irritate the cornea so much that it reacts with inflammation. Dry eyes could also be a common cause. Because if the wetting of the cornea no longer works and it dries out as a result, it can react with irritation that leads to inflammation. Even UV radiation can harm the cornea, which is often underestimated. If you spend hours in the sun without sunglasses, you are risking corneal inflammation, which can be painful.

A compromised immune system (e.g. immunodeficiency or intake of immunosuppressants) can also promote keratitis.

The symptoms differ depending on the cause of the inflammation. They can occur with different combinations and degrees of severity. Corneal inflammation manifests itself, for example, through:

• severe eye pain
• eyelid spasms
• redness of the eye
• burning
• foreign body sensation
• sensitivity to light
• a cloudy cornea
• watery or purulent secretion
• change in visual acuity

It often happens that the symptoms are not only limited to the cornea. The inflammation can also spread to the surrounding structures such as the conjunctiva or iris. An eye specialist should be consulted to treat the symptoms properly.

Treatment of corneal inflammation should always be conducted by an eye specialist. During the examination with a socalled slit lamp, the specialist can examine the cornea more accurately for damage and inflammation. The pathogen can be determined by examination of a smear in a laboratory. Corneal inflammation is also treated in this way:

• The doctor will usually prescribe antibiotic eye drops for bacteria.
• Tablets or eye ointments containing a virostatic agent (e.g. aciclovir) are effective against herpes viruses.
• Fungi and parasites can only be controlled by fungicides and germicidal eye drops.
• Dry eyes are usually treated with lubricating eye drops. They ensure that the tear film gives the corneal surface sufficient protection again.

Corneal inflammation has the same risk of infection as conjunctivitis. If the cause is an infection with a pathogen, the disease is also contagious. As viruses, bacteria and fungi can be transmitted to other people, you should avoid physical contact and pay special attention to hygiene. Wash your hands regularly and always use your own towel during the illness.

If your eye starts to water or even discharge pus, it is best to remove the secretion with a paper handkerchief, which you should then throw away immediately. This reduces the risk of a smear infection.

Rapid treatment of corneal inflammation is very important. If it is not recognised and is allowed to progress, it can even lead to permanent loss of vision. However, if the causes of the eye disease are identified in time, it is easily treatable. In most cases, it takes one to two weeks for the corneal inflammation to disappear. However, very severe cases can take longer.