Keratitis: what is it?

By Cristiano Antonino On Mar 28, 2023

The medical-ophthalmological term “keratitis” indicates an inflammatory process generated to damage the cornea, the transparent part that frontally wraps the eyeball, as well as the first lens of the optical path constantly covered with tear film

The nature of this inflammatory process can be infectious or non-infectious and can present in an ulcerative or non-ulcerative form.

The causes of an infectious keratitis can be:

Bacteria
Mushrooms
Virus
Parasites

Non-infectious keratitis can instead be generated by:

Altered trophism of the cornea
Alteration of the tear film
Trauma
Chemical agents
physical agents

Severity is variable and an etiological diagnosis, i.e. of the triggering factor, is essential, especially in the forms that affect the central portion of the cornea in order to promptly identify the right treatment and prevent any visual impairment that may be permanent.

Keratitis, depending on its specific characteristics, can be classified in:

Superficial keratitis: leaves no visible scar on the cornea after healing.
Deep keratitis: more serious, after healing it can leave scars and marks known as corneal leukoma which – if positioned near the visual axis – can reduce the patient’s vision.
Actinic keratitis: form of keratitis caused by excessive exposure to ultraviolet rays.
Disciform, punctate, and dendritic keratitis: These are non-suppurative or interstitial forms of keratitis that affect the middle and deep layers of the cornea.
Conjunctivitis and nasal keratitis: These are marginal forms of keratitis.
Annular abscess: very serious form of suppurative keratitis that affects the entire cornea in extension and thickness.
Serpiginous ulcer and Mooren’s ulcer: they are suppurative forms of keratitis, ulcerative and peripheral (rarer).

What are the causes of keratitis?

Among the causes of the appearance of non-infectious keratitis, we find physical agents, chemical agents and biological agents.

The most common physical agents are excessive and prolonged exposure to the harmful action of ultraviolet rays.

Among the chemical agents, acids and alkaline substances are responsible for causing keratitis.

Keratitis can also be caused by surgical trauma or by external agents that have penetrated the eye; in rare cases, it could also be caused by excessively prolonged use of contact lenses.

Instead, the causes of an infectious keratitis are various biological agents, such as bacteria, fungi, chlamydia, viruses and protozoa.

Keratitis: symptoms

The forms of keratitis are always symptomatic, so much so that the signs of the disease – whether perceived by the patient or observable with the naked eye – manifest themselves at the ocular level in an absolutely tangible and almost unequivocal way.

In almost all patients, the first recognizable symptom is severe eye pain that occurs rapidly, accompanied by photophobia (intolerance to light), hyperemia (red eyes) and excessive tearing.

Alongside this typical symptomatology, the patient suffering from keratitis often complains of an alteration of vision, as if the latter were blurred, and the continuous sensation of having a foreign body inside the eye.

If left untreated, keratitis can progress to affect the entire cornea, compromising the patient’s vision.

The evolution of untreated keratitis could be a corneal ulcer with the risk of perforation, a very serious event that leads to communication and contamination of the anterior chamber of the eye with the outside.

Diagnose keratitis

The signs of keratitis, however evident, are difficult to trace back to the real causes of the disease as – whether it is a keratitis due to physical, chemical or biological agents – the symptoms will always be the same.

The diagnosis of keratitis – conducted by the competent specialist, the ophthalmologist – begins with an accurate anamnesis, which consists of an investigation into the symptoms and lifestyle and/or work habits conducted by the patient himself.

Subsequently, the ophthalmologist will carry out the physical examination, evaluating the appearance of the conjunctiva, eyelids, lacrimal apparatus and – above all – the cornea and its sensitivity.

This close observation of the various ocular structures is generally done with the help of a special instrument – the slit lamp – which emits a beam of light through a magnifying glass, allowing the ophthalmologist an optimal and close-up view of the iris, of the cornea, the lens and the space between the cornea and the lens.

By observing the conjunctiva, the ophthalmologist will look for any inflammation or structural alterations at the level of the follicles, papillae, the presence of ulcers, scars or foreign bodies; at the level of the eyelid margins, you will look for any anomalies and inflammatory processes; will evaluate the state of the tear film by identifying any symptoms of dry eye; at the level of the cornea, she will look for any edema, ulceration of the stroma, perforations or thinning; at the level of the sclera, you will look for any ulcers, inflammation, thickness or presence of any nodules.

In selected cases, the doctor may also make use of some specific microbiological tests, in order to identify the possible responsible organism.

Some tear samples and corneal cells will then be taken from the patient to be sent to an analysis laboratory, which will culture them and perform GRAM stains to trace the specific infectious cause of the keratitis.

Keratitis: the most suitable therapy

Based on the analyzes conducted both by the ophthalmologist during the specialist visit, and on the possible results of the microbiological tests, the patient will be given specific treatment for his type of keratitis.

The objectives to be pursued in the event of keratitis will be to remove the causal agent, keep the inflammation under control and then eliminate it, and promote the regrowth of the epithelium damaged by the keratitis.

In the case of infectious bacterial keratitis, topical antibiotics in the form of eye drops or ophthalmic ointment can be used.

In some cases, short-acting cycloplegic drugs may also be useful to relieve the painful symptoms, which will produce a temporary blockage of the parasympathetic nerves so as to favor pupil dilation and release of the ciliary muscle.

If the keratitis was caused by an autoimmune disease, corticosteroid eye drops could be used in the therapy.

In any case, the therapy will be accompanied by the administration of artificial tears to favor the lubrication of the eye, which often – in the case of keratitis – has a high degree of dryness.

In the case of infectious keratitis, which given their nature tend to progress and worsen rather rapidly, it will be necessary to intervene promptly to stem the possible consequences of the disease.

Based on the causative agent, identified in some cases thanks to microbiological tests conducted in the laboratory on samples taken from the patient, the treatment for keratitis may include the administration – topically, by mouth or intravenously – of antibiotics, antiviral or antifungals.

How to prevent keratitis?

For all those who are frequent contact lens wearers, preventing keratitis is only possible by using the devices properly, with thorough cleaning, following the instructions: prefer disposable contact lenses, to be changed daily; avoid sleeping with contact lenses on; wash and dry your hands thoroughly before inserting or removing your lenses; handle the lenses carefully to avoid scratching them; always use good quality lenses and special tools for cleaning them; do not use contact lenses in the pool or sea.

If you suffer from dry eye syndrome or if you often use contact lenses to prevent the onset of keratitis, it will be good to always use artificial tears to keep the area well lubricated.

In case of a viral infection, never touch your eyes with your hands.

Do not use cortisone eye drops before consulting your ophthalmologist: their careless use could worsen the clinical picture and in some cases cause permanent visual damage.

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