What is a Corneal Ulcer
A corneal ulcer is a serious corneal injury, usually caused by an inflammatory process or an infection.
The corneal ulcer is similar to an open wound and is characterized by the interruption of the epithelial layer (superficial), with involvement of the stroma (deeper corneal layer) and underlying inflammation.
The symptoms of a corneal ulcer depend on the cause, the size and the depth of the lesion. The cornea is very sensitive, so even small abrasions can cause tearing, redness and pain. The corneal ulcer may be associated with hyperemia and stratification of white blood cells in the anterior ocular chamber (ipopion).
The treatment, usually based on topical antimicrobials, must be immediate to prevent complications and permanent damage; delayed or ineffective treatment of corneal infections can in fact lead to devastating consequences.
Causes
Corneal ulcers can be caused by trauma, chemical damage, incorrect use of contact lenses, corneal dystrophy and dry keratoconjunctivitis (dry eye). Other ocular lesions are caused by eyelid abnormalities: entropion, exophthalmos, trichiasis and distichiasis (growth of the eyelashes in anomalous position and orientation).
Many pathogenic microorganisms are implicated in the onset of corneal ulcer. Among them are bacteria ( Staphylococcus aureus, Streptococcus viridans, Escherichia coli, Enterococci, Pseudomonas, Chlamydia trachomatis etc.), fungi ( Aspergillus sp ., Fusarium sp ., Candida sp . And others), viruses ( Herpes simplex, Herpes Zoster and Adenovirus ) and protozoa ( Acanthamoeba ).
Common infections that can lead to the onset of a corneal ulcer are:
- Acanthamoeba keratitis : Acanthamoeba is a single-celled amoeba mainly found in soil and wastewater. Infection occurs mainly in contact lens wearers, most commonly due to exposure to contaminated water. Corneal ulcers from Acanthamoeba are often intensely painful and may show transient epithelial defects and, later, a large ring-shaped infiltrate.
- Herpes simplex keratitis : it is a viral infection that causes a dendritic corneal ulcer and which, during the life of an individual, can recur with recurrent stress-activated attacks, exposure to sunlight or any other condition that weakens the immune system .
- Fungal keratitis : develops after a corneal injury most commonly caused by trauma with plant material, improper use of contact lenses or steroid eye drops. A fungal ulcer is deep, but typically presents with slow onset and gradual progression; it is densely infiltrated and shows occasional small satellite lesions on the periphery. Fungal keratitis can also develop in people with weakened immune systems.
The non-infectious causes, each of which can be complicated by an over-infection, include:
- Neurotrophic keratitis (resulting from loss of corneal sensitivity);
- Corneal exposure keratitis (due to inadequate closure of the eyelids, such as in the case of Bell's palsy);
- Severe allergic eye disease;
- Various inflammatory disorders, which may be exclusively ocular or part of a systemic vasculitis.
Other causes of corneal ulcers are: foreign bodies in the eyes, abrasions on the ocular surface or nutritional deficiencies (in particular of vitamin A)? ‹. People who wear contact lenses, especially if soft, for a long period (even during the night), expired or inadequately cleaned and disinfected, have an increased risk of developing corneal ulcers.
Superficial and deep ulcers
Ulcers are characterized by epithelial lesions of the cornea with underlying inflammation, which may soon develop into necrosis of the stroma. Superficial lesions involve a loss of part of the epithelium, while deep ulcers extend through the stroma and tend to heal with scar tissue, resulting in opacification of the cornea with a decrease in visual acuity. Uveitis, corneal perforation with iris prolapse, pus in the anterior chamber (ipopion) and panophthalmitis (purulent inflammation of the eyeball) are consequences that can occur in the absence of treatment and, sometimes, even with the best therapy available, especially if medical intervention is delayed. More severe symptoms and complications tend to occur with deep ulcers.
The position of the corneal ulcer may depend on the triggering cause. Central ulcers are usually caused by trauma, dry eye or corneal exposure from facial nerve paralysis or exophthalmos. Entropy, severe eye dryness and trichiasis can cause peripheral corneal ulceration. Immune-mediated eye diseases can cause ulcers on the border of the cornea and sclera; these diseases include rheumatoid arthritis, rosacea and systemic sclerosis. The latter, in particular, induces a particular type of lesion called the Mooren ulcer, which appears as a circumferential crater, usually with a protruding edge, as if it were a depression of the cornea.
Corneal healing
A corneal ulcer can heal in two ways: by cell division and migration of surrounding epithelial cells or by the introduction of blood vessels from the conjunctiva (corneal neovascularization). Small and superficial lesions heal quickly with the first mechanism. However, larger or deeper ulcers often require the presence of blood vessels to supply the area with inflammatory mediators. White blood cells and fibroblasts produce granulation tissue, and therefore scar tissue, which repairs the cornea, but compromises vision.
Symptoms
To learn more: Corneal Ulcer Symptoms
The main symptoms of a corneal ulcer are:
- Blurry or confused vision;
- Itching, burning, excessive tearing, redness and eye pain;
- Swollen eyelids;
- Pus or purulent eye discharge;
- Photophobia (light sensitivity);
- Sensation of a foreign body in the eye.
All symptoms are severe and must be treated immediately to avoid blindness.
Corneal ulcers are extremely painful due to the exposure of nerve endings. An ipopion (white blood cells stratified in the anterior chamber) can produce blurred vision or alter colors.
Clinical signs
A corneal ulcer begins as a defect of the epithelium, which at the sight appears as a greyish and circumscribed superficial stain or opacity (usually, the cornea is transparent) and is colored with fluorescein. Some injuries are too small to be visualized without magnification, even if the patient may still experience symptoms.
Subsequently, the ulcer can become suppurative and necrotize, until it forms a corneal depression. A considerable conjunctival hyperemia is usual.
In long-standing cases, blood vessels can grow from the limbus (corneal neovascularization). The ulcer can spread to involve the width of the cornea or can penetrate deeply.
Complications
Most complications occur when the corneal ulcer is not adequately treated. Typically, therapy can prevent complications such as:
- Severe vision loss;
- Scars on the cornea;
- Loss of the affected eye (rare);
- Cataract or glaucoma;
- Spread of infection to other parts of the eye and body.
Diagnosis
An ophthalmologist can diagnose a corneal ulcer using the classic slit lamp exam. A corneal infiltrate, with an epithelial defect stained with fluorescein, offers diagnostic confirmation. All ulcers should be scraped and cultivated? ‹To identify the responsible pathogens. Blood tests can also be performed to check for the presence of particular inflammatory diseases or other predisposing factors, such as diabetes mellitus and immunodeficiency. Proper diagnosis is essential for optimal condition management.
Fluorescein staining
Diagnosis is made by direct observation with a slit lamp. The use of fluorescein helps define the corneal ulcer margins and may reveal additional details of the surrounding epithelium. This test is performed by placing a drop of orange dye on a thin sheet of absorbent paper, with which the surface of the eye is then lightly touched. The doctor, therefore, with a slit lamp with blue light, looks for any areas that appear green (they correspond to the lesion of the cornea). Herpetic ulcers show a typical pattern of dendritic staining.
Corneal scraping
To determine the cause of the corneal ulcer, the doctor can numb the eye with eye drops and gently scrape the lesion with a sterile spatula to obtain a sample. Microbiological cultures and sensitivity tests on the corneal scraping sample allow to isolate the responsible pathogenic microorganisms and establish the appropriate therapy.
Treatment
Treatment of corneal ulcer depends on the cause and must be started as soon as possible, to avoid scarring of the cornea. Antimicrobial therapy is specific and directed towards the causative agent:
- Bacterial corneal ulcers require intense therapy to treat the infection. Topical antibiotics are given at 1-2 hour intervals.
- Mycotic corneal ulcers require intensive application of topical antifungal agents.
- Corneal ulcers caused by Herpes viruses may respond to antiviral drugs, such as acyclovir topical ointment, instilled at least five times a day.
If the exact cause is not known, patients may initially be given broad-spectrum antibiotic therapy. At the same time, supportive therapy based on pain-relieving drugs and cycloplegic eye drops, such as atropine, can be prescribed to stop spasms of the ciliary muscle and reduce inflammation.
Superficial ulcers can heal in less than a week. Deep lesions may require conjunctival grafts or soft contact lenses. A corneal transplant can be performed in the case of progressive or refractory corneal ulcer.
Patients who are poorly compatible or have a large, central or refractory lesion may need to be hospitalized. In cases of keratomalacia, where corneal ulceration is due to a vitamin A deficiency, retinol supplementation is administered orally or intramuscularly. The use of steroid eye drops is controversial, as they can worsen the infection.
Your doctor may also recommend:
- Avoid eye makeup;
- Do not wear contact lenses;
- Wear an eye patch to help relieve symptoms.
The healing takes from about a couple of weeks to several months. Many people recover completely after treatment or experience only a slight reduction in vision. However, a corneal ulcer can cause permanent damage and impair visual function, due to the obstruction related to scar tissue. In rare cases, the entire eye can be damaged.
