Keratitis is an inflammation of the cornea of the eye.
The cornea is a transparent layer that covers the front eye.
As a rule, keratitis affects one eye, but it can also occur on both sides.
Classification of keratitis
The fungal keratitis or mycotic keratitis or is caused by a fungus.
Types of fungi that can cause keratitis include:
Fusarium and Aspergillus live in the area, often on plants.
Fungi of Candida are microorganisms that normally live on human skin and mucosa.
Although fungal keratitis can be a serious disease, it is relatively rare (6-20%).
Organisms that most often cause keratitis are:
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Streptococcus pneumoniae
- Mycobacterium (Mycrobacteria)
Infections with ulceration cause the following symptoms:
Marginal or limbic keratitis
It is a hypersensitivity reaction of the eye to a conjunctival infection with bacteria, especially Staphylococcus aureus.
It manifests itself with the following symptoms:
- Congestion in the limbus corneae
The limbus corneae (border between cornea and sclera) may be characterized by elongated ulcers and corneal infiltrates.
Typically, the ulcers are not distributed centrally.
Viruses such as the herpes virus (herpes simplex and herpes zoster), the mumps virus, and the virus that causes chlamydia can cause keratitis.
Among the most common types is keratitis caused by the herpes simplex virus. The same virus also leads to cold sores (herpes labialis).
This infection usually begins with inflammation of the conjunctiva, a membrane that covers the eyelid and the part of the eyeball that comes into contact with it.
The subsequent infections are called “keratitis dendritica” and are characterized by a lesion pattern that resembles the veins of a leaf.
The herpes simplex virus can also lead to keratitis disciformis, which is an inflammation with edema formation in the corneal stroma. Symptoms include a grayish disc-shaped discoloration.
Anyone who is sick with a herpes simplex virus must be careful, because if this form of keratitis is not treated, it can have serious consequences such as:
After the initial infection, the virus is in a dormant state and lives on in the nerve cells of the skin or eye. Reactivation can be done in several ways, including:
- Exposure to sunlight
- Trauma (accidents or surgical interventions)
- Some medications
Herpetic keratitis can spread to the eyelids, conjunctiva (the thin mucous membrane of the inside of the eyelid and white areas of the eye) and cornea. Rarely, the inside of the eye is also infected.
Other types of viruses that cause keratitis include varicella zoster viruses associated with chickenpox, herpes zoster, and adenovirus, which causes upper respiratory tract infections.
Keratitis nummularis – a viral keratitis characterized by disc-shaped whitish and granular spots in the center of the cornea.
Keratitis punctata – an inflammation of the cornea characterized by small grayish dots on the corneal epithelium.
Thygeson’s keratitis – a rare disease in which small corneal injuries form in both eyes.
Acanthamoeba keratitis is a rare but serious eye infection that can lead to permanent vision loss or blindness.
This infection is caused by amoebas or protozoa, the so-called Acanthamoeba.
Acanthamoebas occur naturally in water (for example in lakes and oceans), in soil and in the air.
What are the symptoms of Acanthamoeba keratitis?
The symptoms of acanthamoeba keratitis can be very similar to the symptoms of other infections of the eye. These include:
- Severe eye pain
- Red eyes
- Blurred vision
- Increased lacrimation
- Ulcers and erosions of the cornea
Symptoms can persist for several weeks and months.
Acanthamoeba keratitis causes severe pain and blindness if left untreated.
Who is at risk from keratitis?
Acanthamoeba keratitis is more common in people who wear contact lenses. But everyone can get it.
For contact lens wearers, certain actions may increase the risk of keratitis, for example:
- incorrect storage of contact lenses;
- inadequate disinfection of contact lenses (for example, when using tap water);
- swimming, wearing contact lenses in the hot tub or in the shower;
- contact with polluted water;
- previous trauma to the cornea.
Types in keratitis by manifestation
Keratitis phlyctaenulosa. Caused by Koch’s bacillus and is characterized by the appearance of nodules or yellowish or grayish blisters (phlyctaenes) and ulcers on the corneal margin and conjunctiva (keratoconjunctivitis).
This type of keratitis occurs mainly in children.
Keratitis filiformis. The surface cells of the cornea are formed by filaments that, when torn off, leave very small painful ulcers.
Ulcerative or superficial keratitis. Affects the outermost layers of the cornea and is caused by:
- lacrimal fluid deficiency,
- complete inability to close the eyelids.
The consequence of this disease is the possible formation of severe corneal ulcers.
Interstitial keratitis. A chronic inflammation that affects the deepest or innermost parts of the cornea and can be caused by a virus or allergy.
Bandkeratitis. Characterized by calcium deposits at the edge of the cornea, at the level of the surface stroma and the Bowman membrane.
On both sides of the cornea, a band-shaped turbidity develops.
Diffuse lamellar keratitis (DLK). May occur after LASIK surgery (eye laser) by infiltrates (cells) under the corneal flap raised during the procedure.
Cleaning of this area may be necessary to remove the cells causing the inflammation.
Bullous keratopathy. Characterized by the formation of fluid-filled blisters under the corneal epithelium.
Possible causes are:
- trauma (for example, after eye surgery),
- Fuchs dystrophy, i.e. a degeneration of the corneal epithelium.
Neurotrophic keratitis. A degenerative disease caused by damage to the corneal nerves.
Typical features are:
- Decreased lacrimation – the nerves are stimulated when the eye temperature drops due to the evaporation of the tear fluid. In this situation, a signal is sent to increase the production of tear fluid; however, if there is a nervous dysfunction, this signal does not occur;
- Reduction of stimuli for cell proliferation, a loss of sensitivity thus does not allow cell replication in the event of injury.
Causes of keratitis
Injuries. If an object rubs on the surface of an eye or penetrates the cornea, keratitis can be caused even without infection.
In addition, a wound allows bacteria or fungi to penetrate through the damaged surface of the cornea and thus cause infections.
Contaminated contact lenses. Bacteria, fungi or parasites that colonize the surface of a contact lens can contaminate the cornea after insertion into the eye and thus cause infectious keratitis.
Contaminated water. Chemicals in the water, such as those used in swimming pools, can irritate the cornea and cause damage to the delicate tissue of the corneal surface (corneal epithelium), resulting in chemical keratitis.
This is usually limited in time and can last from a few minutes to a few hours.
But even if you come into contact with these bacteria, fungi or parasites, a healthy cornea is difficult to become infected if there is no previous lesion of the corneal epithelium.
For example, fatigue of the corneal epithelium from wearing a contact lens for too long can make the cornea susceptible to infection.
UV radiation. Exposure to UV radiation (from UV lamps, sunlight, welding equipment) without proper protection can burn the cornea and lead to actinic keratosis.
Actinic keratosis and herpetic keratitis are the most common causes of keratitis in children.
Symptoms of keratitis
Signs and symptoms of keratitis and corneal ulcer include:
- Reddened eyes
- Watery eyes
- Pain and irritation that hinder the opening of the eyelids
- Burning, itching or scratching sensation in the eye
- Swelling around the eyes
- Foreign body sensation in the eye
- Blurred vision
- Light sensitivity (photophobia)
What other diseases are associated with keratitis?
A corneal infection can be caused by the following diseases:
- diseases affecting the eyelids;
- thyroid diseases;
- serious systemic allergies involving the eyes;
- Autoimmune diseases, especially rheumatoid arthritis and vasculitis. They are a risk factor for the development of keratitis and corneal thinning, which may require surgical intervention.
Diagnosis of keratitis
The ophthalmologist diagnoses keratitis by examining the patient with a slit lamp.
Evaluation of medical history is always important in inflammatory diseases.
However, to find out the cause of keratitis, some research may be needed, such as:
- blood tests,
- smear and culture of eye fluid,
Treatment of keratitis
Early treatment by the ophthalmologist is important to determine the specific type of keratitis and choose the appropriate therapy.
It is important that the ophthalmologist knows that diseases had already preceded, such as:
The doctor examines the surface of the cornea for small ulcers or other abnormalities.
Treatment of viral keratitis
Antiviral eye drops and systemic treatment with antiviral drugs are usually used to treat symptoms caused by herpes simplex type 1 or by other viruses.
However, these may recur in the future as the virus can remain in the body.
In the most severe cases, the doctor may remove the diseased tissue after administering numbing eye drops.
Treatment of infectious keratitis
Antibacterial or antifungal eye drops can be used to treat the corneal infection.
Eye drops with corticosteroids may be necessary to reduce inflammation (swelling) in keratitis.
If contact lenses are worn, it may be necessary to suspend use for a few weeks and replace the lenses.
In those cases provoked by dry eye, artificial tear fluid is effective as a lubricating fluid. Vitamin supplements are prescribed in cases where there is a suspicion of vitamin A deficiency.
If the cornea is severely injured or thinned, a corneal transplant may be needed to restore vision.
It is important to remember that keratitis must be treated early to avoid risks of complication and it is possible to visit the ophthalmologist more often before the problem is completely resolved.
Treatment of Acanthamoeba keratitis
Prevention is always the best precaution, because acanthamoeba keratitis can be extremely difficult to treat; in fact, sometimes the cure from this infection is only possible through a corneal transplant.
Therapy and results in fungal keratitis
To cure fungal keratitis, a medically prescribed antifungal drug is used for several months.
Natamycin is a local ophthalmic antifungal drug that works well for superficial corneal infections, especially those caused by yeasts (Candida) and filamentous fungi, such as some species of Fusarium.
Very serious and deep corneal infections must be treated with systemic antifungal drugs, for example:
- Amphotericin B,
Patients for whom drug therapy does not bring any improvement may need surgery.
How long does keratitis last? Recovery times
Recovery times vary greatly and depend on the cause and condition of the patient.
A natural and anti-inflammatory diet, combined with the right food combinations, is essential for rapid healing.
- If the keratitis is superficial, then with healing there are no complications.
- With deep keratitis, permanent scars called leucomas can form. The result is partial or complete blindness.
How to prevent a relapse of acanthamoeba keratitis?
There are a few simple ways to reduce the risk of developing this disease, which is dangerous for vision:
- Follow the advice of the ophthalmologist regarding the care of contact lenses.
Only use products recommended by him.
- Do not use tap water to clean contact lenses.
Do not bathe, shower or use a hot tub with contact lenses.
If you decide to wear the contact lenses while swimming, put on hermetically sealed safety goggles over the well-fitting lenses.
- Place the contact lenses in a new disinfectant solution every night. Do not use a physiological solution for disinfection that is not intended for it.
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