A corneal ulcer is a lesion of the epithelium of the cornea, which can also involve and penetrate deeper corneal layers such as the stroma.
The cornea
The cornea is a transparent membrane devoid of vessels, but rich in nerve fibres. It is continuously wetted by the tear film that adheres to its surface. The tear film-corneal surface interface constitutes the most powerful converging lens in the human eye.
The cornea is about 1 mm thick and consists of five layers from outside to inside:
- a pavimentous (stratified) epithelium,
- Bowman's membrane,
- the stroma,
- Descemet's membrane,
- the endothelium.
Risks to vision
It is a potentially sight-threatening condition because, even with timely treatment, patients may experience complications, including corneal scarring or perforation, glaucoma, cataracts or synechiae (pupillary adhesions) and loss of vision. It is therefore essential that the corneal ulcer is diagnosed and treated promptly.
Aetiology
Most corneal ulcers are of infectious origin, the main causes being:
- bacterial infectionscommonly caused by contact lens wear, corneal abrasions or ocular trauma, other risk factors include diabetes, ocular surgery, chronic eye diseases, use of corticosteroids or contaminated eye medications and agricultural work;
- viral infectionsherpes viruses are the most common cause of viral keratitis as well as unilateral infective corneal blindness in developed countries;
- fungal infections, account for 5-10% of all corneal infections. They are very common in hot and humid rural environments and often result from corneal trauma followed by exposure to plants or plant material;
- protozoan infections, among them Acanthamoebapresent in fresh water and soil, can cause keratitis and corneal ulcers, mainly in contact lens wearers.
Although most corneal ulcers are infectious in origin, there are also non-infectious causes or causes associated with collagen vascular diseases.
Symptoms
The wound, no matter how small, usually causes a sensation of discomfort, such as the sensation generated by the presence of a foreign body in the eye, or actual pain, tearing, often hypersensitivity to light, and sometimes blurred vision.
Diagnosis of corneal ulcer
The physical examination for the diagnosis of corneal ulcer includes visual acuity testing, measurement of intraocular pressures and examination of pupillary function. It will also be necessary for the ophthalmologist to determine the size, position and shape of the lesion.
In general, the most common symptoms of corneal ulcer recognised by the doctor include pain, photophobia, redness and a variable degree of vision loss.
Treatment of corneal ulcer
Medical therapy depends on the extent of the damage and consists of three stages.
- Cleaning: the first intervention by the ophthalmologist consists of cleaning the wound, with the possible removal of the foreign body or substance with which the eye came into contact
- Medication, which aims at three results:
1. lubricate the ocular surface to facilitate the reparative processes of the ocular surface
2. protect the wound area from rubbing forces, environmental irritants and prevent the superimposition of an infection
3. encourage the establishment of new intact tissue.
To achieve all three of these goals, the most effective solution is to use a medicine that has a long dwell time on the ocular surface and contains no preservatives.
The advantages of gels
The most commonly used pharmaceutical forms are ointments and gels. Unlike ointments, which are uncomfortable because they are non-transparent and very viscous, gels do not blur vision by ensuring lubrication and hydration of the eye.
In the case of extensive and/or deep lesions, in addition to the above treatment, the ophthalmologist usually also applies an eye patch for about 2-3 days to reduce eyelid rubbing and facilitate the corneal repair process.
The drugs used
The treatment of corneal ulcers consists, in the first instance, in the administration of topical antibiotics, in some cases the ophthalmologist may also decide to prescribe adjuvant corticosteroids.
In the case of corneal ulcers of viral origin, treatment includes topical antivirals and adjuvant topical steroids. Fungal ulcers tend to have worse outcomes than bacterial ulcers because far fewer treatment options are available.
Corneal ulcers and contact lenses: the importance of patient education
The most significant risk factor for corneal ulcers is incorrect contact lens wear. Therefore, patient education on the correct wearing and handling of contact lenses is one of the most important aspects in the prevention of this disease. Indeed, it is essential that the contact lens wearer has clear instructions on how to wear, clean and store them correctly, as well as the importance of avoiding night or prolonged wear and the risks associated with wearing them during water sports.
On the subject of corneal injuries, see also:
- Treatment of corneal abrasions - Oculista Italiano
- A novelty for repairing corneal lesions - Oculista Italiano
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