Diseases
Kératitis
Definition
Keratitis is an inflammation of the first layer of the cornea, called the epithelium, which can cause severe pain due to its extensive innervation. Most often unilateral, keratitis can also affect both eyes and be associated with inflammation of the conjunctiva. It requires an ophthalmological consultation.
There are several types of keratitis:
- Bacterial keratitis: this type of keratitis is the most common, but must be treated to avoid the serious complication of corneal perforation.
- Herpetic keratitis: the herpes simplex virus is responsible for this infection, which often recurs and can even affect the deeper layers of the cornea and the iris. There are three types of herpes simplex keratitis (classified in order of severity): epithelial, disciform and stromal. Medical follow-up is necessary, as recurrences can result in ulceration, opacification, scar opacity, thinning of the corneal stroma and reduced vision.
- Viral keratitis: this is most often caused by herpes simplex, but adenoviruses can also cause viral keratitis, known as kerato-conjunctivitis, when inflammation of the cornea is added to that of the conjunctiva.
- Amebic keratitis: rare, this type of keratitis is caused by free-living amoebae and most often appears in contact lens wearers, although it can also occur in non-wearers, particularly after ocular trauma or exposure to contaminated water. A painful ulceration develops on the cornea and can impair vision. Medical follow-up is therefore necessary to make a rapid diagnosis and introduce treatment as early as possible.
- Traumatic keratitis: this is very painful and is mainly caused by a foreign body, fingernail or chemical being thrown into the eye, or by a burn to the corneal epithelium.
Toxic keratitis: often caused by the incorrect use of certain eye drops.
Causes
The causes depend on the type of keratitis and can be very diverse:
- Viral or bacterial infection
- Amoeba infection
- Poor hygiene of contact lenses
- Prolonged contact lens wear
- Dry eyes
- Ocular trauma
- Contact with chemicals
- Exposure to ultraviolet light
- A reaction to certain eye drops
- Blepharitis
Symptoms
There are several symptoms, although they may differ depending on the type of keratitis:
- Pain
- Intense photophobia
- Red eyes (a circle around the cornea may form)
- Tearing
- Sensation of a foreign body in the eye
- Impaired vision
Diagnosis
Diagnosis is based on a clinical examination of the symptoms and exposure to one of the known causes of the condition. Slit lamp examination is also necessary, especially in the case of herpetic keratitis, where the presence of ulceration helps to confirm the diagnosis.
If amoebic or bacterial keratitis is suspected, a sample taken from the cornea can be cultured to determine the pathogen responsible for the infection. If the patient wears contact lenses, these may also be analysed.
Treatments
In the case of bacterial keratitis, a broad-spectrum antibiotic may be prescribed pending the results of the culture, which will then determine a targeted course of antibiotics. Ointments or eye drops may be added to the treatment to help healing and relieve symptoms.
Most patients with herpetic keratitis receive medical follow-up. This applies to epithelial and disciform keratitis, but is even more important for stromal keratitis, which can lead to necrosis of the stroma and irreversible loss of vision. Antiviral treatment is prescribed and corticosteroids may be combined with it for disciform or stromal keratitis (although they are contraindicated for epithelial keratitis).
Antimicrobial treatment (often in the form of eye drops) must be started quickly for amoebic keratitis. It lasts between 6 and 12 months, depending on the degree of healing, and should not be stopped too early to avoid the risk of recurrence. Sometimes, the treatment may be ineffective and corneal repair surgery may be necessary (this is also the case if the diagnosis was made too late).
Prevention
Generally speaking, good hand and contact lens hygiene helps to limit the risk of keratitis:
Always keep your hands clean when handling contact lenses
Never clean contact lenses with water
Store contact lenses in the appropriate storage liquid.
Do not misuse contact lenses for long periods of time
Remove contact lenses in the shower or in swimming pools/jacuzzis.
If you experience any pain after wearing contact lenses, remove them and consult an ophthalmologist.
References
Microsoft Word - oeil rouge_arce.docx (hug.ch)
Kératite et ulcère de cornée - Erosions de l'œil (centreophta.com)
Le trichiasis - Centre Médico Chirurgical Paris - Oeil et Paupière (oeiletpaupiere.fr)
Kératite herpétique - Troubles oculaires - Édition professionnelle du Manuel MSD (msdmanuals.com)
Kératite amibienne (infection oculaire) - Infections - Manuels MSD pour le grand public (msdmanuals.com)
Kératite et ulcère de cornée - Erosions de l'œil (centreophta.com)