The different forms of corneal inflammation
In most cases, the causative agents are the Herpes Simplex virus, the Varicella zoster virus (otherwise causes chickenpox and shingles) and the adenoviruses. If the inflammation flares up again after a previous infection (with blistering of the eyelid), herpes keratitis develops, since the herpes viruses survive for life in nerve branches. Zoster keratitis occurs after previous chickenpox and develops in the context of shingles of the face and eye.
Adenovirus keratitis is a new infection and occurs in combination with conjunctivitis. In addition to reddening of the eye, pain and foreign body sensation, a branched defect in the cornea becomes characteristically apparent as typical symptoms when looking at the eye. This can be made more clearly visible by applying the dye fluorescein.
In case of herpes infestation, the sensitivity of the cornea is also reduced, which can be tested with a cotton swab. Zoster keratitis is usually conspicuous by shingles with blister formation on the facial skin, while symptoms on the eye itself rarely exist. Nevertheless, corneal inflammation can lead to further damage to and in the eye.
Adenovirus keratitis (epidemic keratitis and conjunctivitis) is characterized by redness, swelling and secretion of the conjunctiva. Punctiform defects on the surface of the cornea also lead to clouding for weeks to months and thus to a deterioration of visual acuity. Infections of the cornea caused by Herpes simplex and Varizella zoster can be treated with antiviral drugs (e.g. Aciclovir), which are given as eye drops or even as tablets or infusions.
However, conjunctivitis and corneal inflammation caused by adenoviruses cannot be treated with drugs, so that the main therapy here is to prevent infections in people who come into contact with the diseased. Most corneal infections of this form are caused by the yeast fungus Candida albicans. The infection is often caused by injuries with fungal material, especially if there is an immune deficiency.
Fungal keratitis often looks like bacterial corneal inflammation, but often causes less discomfort. In addition to a corneal ulcer, small neighbouring ulcers (“satellites”) and pus in the anterior chamber of the eye (hypopyon) are usually present. The detection of the fungi takes place in the laboratory, but is complicated.
The subsequent therapy is carried out with antimycotics (anti-fungal agents), such as Nystatin, Natamycin or Amphotericin B. A dry eye (sicca syndrome) is caused by an inadequate composition of the tear fluid or a lack of tears in general. In addition to chronic conjunctival irritation, this can lead to micro tears in the corneal epithelium (corneal surface).
Eye dryness is determined by various tests, the most important of which is the so-called Schirmer test. Tear substitutes and caring ointments are then used to treat eyes that are too dry or methods such as plugs (punctum plugs) are inserted into the tear duct. If the eyelid is not completely closed, which is especially the case in paralysis of the facial nerve (facial nerve, facial paresis), in eyelid distortion (e.g. after surgery), in protruding eyeballs (exophthalmos) or in unconscious patients, the cornea dries out.
This leads to damage to the surface of the cornea and in some cases to an ulcer.The therapy is carried out with tear substitution fluid, antibiotic and nourishing ointments and usually additionally with a so-called “watch glass bandage”, which keeps the eye moist. Wearing contact lenses for too long or insufficiently adapted to the individual eye can lead to damage to the cornea and conjunctiva. This can lead to microdefects and even ulcers and vessels can grow into the cornea.
As a therapy, an alternative visual aid is provided in the form of glasses and the wearing of contact lenses is discontinued for a longer period of time. In addition, the ophthalmologist may prescribe cortisone to relieve inflammation. The cornea is the front, transparent skin of the eye.
Due to its refraction of light, it contributes to a large extent to the sharp image on the retina. The cornea also has a protective function for the eye and supports the stability of the eye. Tear fluid and eyelid closure ensure that the surface of the cornea is wetted with fluid and thus prevents it from drying out, which can lead to microcracks.
The cornea is divided into three layers: which provides the inner surface. In general, all corneal layers can become inflamed and often several layers are actually affected. If the epithelial cell layer is inflamed, clouding often occurs.
If the stroma is affected, this cloudiness is usually whitish in color. If the endothelium is affected, the cornea often swells up in a disc-shaped manner. In most cases, the conjunctiva is additionally reddened by the irritation caused by the inflammation, which is also a noticeable symptom.
- The outer, thin epithelium,
- The middle, thick stroma
- And the thin endothelium,
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