eMedicine Specialties > Emergency Medicine > Ophthalmology

Corneal Ulceration and Ulcerative Keratitis

Author: Trevor John Mills, MD, MPH, Chief of Emergency Medicine, Veterans Affairs Northern California Health Care System; Associate Professor of Emergency Medicine, Louisiana State University Health Sciences Center
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Updated: Dec 2, 2009

Introduction

Background

Because of its potential to permanently impair vision or perforate the eye, a corneal ulcer is considered an ophthalmologic emergency. Although corneal ulcers may occasionally be sterile, most are infectious in etiology. Ulcers due to viral infection occur on a previously intact corneal epithelium. Bacterial corneal ulcers generally follow a traumatic break in the corneal epithelium, thereby providing an entry for bacteria. The traumatic episode may be minor, such as a minute abrasion from a small foreign body, or may result from such causes as tear insufficiency, malnutrition, or contact lens use. Increased use of soft contact lenses in recent years has led to a dramatic rise in the occurrence of corneal ulcer, particularly due to Pseudomonas aeruginosa. In addition, with the introduction of topical corticosteroid drugs in the treatment of eye disease, fungal corneal ulcers have become more common.

Peripheral ulcerative keratitis (PUK) is a complication of rheumatoid arthritis (RA) that can lead to rapid corneal destruction (corneal melt) and perforation with loss of vision. An example is shown in the image below.

Mooren ulcer is a rapidly progressive, painful, ulcerative keratitis, which initially affects the peripheral cornea and may spread circumferentially and then centrally. Mooren ulcer can only be diagnosed in the absence of an infectious or systemic cause.

Pathophysiology

Risk factors include contact lens use, trauma, ocular surface disease, and ocular surgery. Overnight contact lens wear has been shown to be associated with increased risk. Other identified risk factors include age, gender smoking, low socioeconomic class, and inadequate contact lens hygiene.

Common bacterial isolates cultured from patients with keratitis include P aeruginosa, coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus pneumoniae, and Enterobacteriaceae (including Klebsiella, Enterobacter, Serratia, and Proteus). Klebsiella pneumoniae mucoid phenotype and its ability to form biofilm may be important in producing a corneal ulceration. Agents, such as N- acetylcysteine, may have a role in treatment because they inhibit biofilm formation.

Fungi (Fusarium) and amoeba (Acanthamoeba) have been found in a small number of patients but frequently present with more severe symptoms.

Mooren ulcer is an idiopathic ulceration of the peripheral cornea, which may be due to an autoimmune reaction or it may be associated with the hepatitis C virus.

Frequency

United States

Approximately 25,000 Americans develop infectious keratitis annually. The annual incidence of microbial keratitis associated with contact lens use is approximately 2-4 infections per 10,000 users of soft contact lenses and 10-20 infections per 10,000 users of extended-wear contact lenses. Approximately 10% of these infections result in the loss of 2 or more lines of visual acuity.

International

A study from the United Kingdom reports factors associated with an increased risk of a corneal invasive event: wearing extended-wear hydrogel lenses, male gender, smoking, and the late winter months (March > July).¹

Authors from the United Kingdom also report an 8 times higher incidence of corneal invasive event in contact lens wearers who sleep in contact lenses compared with wearers who use lenses only during the waking hours.²

Mortality/Morbidity

Corneal scarring and vision loss are possible.

Sex

Studies from the United Kingdom suggest that males who wear extended-wear contact lenses are at increased risk of forming a corneal ulcer. 

Other studies suggest that males are at increased risk due to the higher probability of sustaining ocular trauma.

Age

Corneal injury or infection can affect people of all ages. A bimodal distribution is observed. The age groups with a higher prevalence of disease are likely tied to risk factors, those in the first group (<30 y) who are more likely to be contact lenses wearers and/or sustain ocular trauma, and those in the second group (>50 y) who are more likely to undergo eye surgery.

Clinical

History

Numerous symptoms can help determine the diagnosis of keratitis.

• Current symptoms
• Erythema of eyelid and conjunctiva
• Mucopurulent discharge from eye
• Foreign body sensation
• Blurred vision
• Light sensitivity
• Pain
• Medication and contact lens use
• Contact lens use
• Type of contact lens (soft, hard, extended wear)
• Type of contact lens solution
• Contact lens hygiene
• Current ocular medications, especially steroids
• Past medical history
• History of ocular disease, eye surgery, or both
• Diabetes mellitus
• Exposure to sulphur mustard³
• Collagen vascular disease (rheumatoid arthritis [RA])
• Social history
• Smoking history
• Inquiry about the dietary habits of a patient with a corneal ulcer is important because vitamin A deficiency is associated with corneal ulcer formation.
• Inadequate vitamin A can occur in a patient with an intentional diet deprivation or unintentional deprivation found in young children and pregnant women from Africa and Southeast Asia.
• Secondary vitamin A deficiency may be found in a patient with celiac disease, sprue, cystic fibrosis, pancreatic disease, duodenal bypass, congenital partial obstruction of the jejunum, obstruction of the bile ducts, giardiasis, and cirrhosis.

Physical

The physical examination should be thorough, with additional focus on the eye examination.⁴ Visual acuity, gross examination of the eyelids, surface of the eye, pupils, extraocular muscles, and fundi, should be performed and documented. A slit lamp examination and ocular pressure measurements should also be obtained.

• Visual function is variably affected, depending on the location of the ulcer and whether associated corneal and uveal inflammation is present. Obtain visual acuities on all patients with ocular complaints.
• Examination of the lids and the conjunctiva may reveal associated inflammation in these locations.
• The eye is typically erythematous, and ciliary injection is often present. Pupillary constriction is usually present secondary to ciliary spasm and iritis.
• Purulent exudate may be seen in the conjunctival sac and on the surface of the ulcer, and infiltration of the stroma may result in a creamy opacity of the cornea. The ulcer often is round or oval, and the border generally is demarcated sharply, with the base appearing ragged and gray.
• Slit lamp examination may reveal findings of iritis, and hypopyon may be present. Hypopyon is an accumulation of inflammatory cells in the anterior chamber that produces a layered meniscus in the inferior anterior chamber.
• Fluorescein staining may reveal the characteristic dendritic ulcer of herpes simplex virus infection.
• A Wood lamp may be useful because the ulcer associated with P aeruginosa fluoresces in ultraviolet light.

Causes

• Viral infections
• Herpes simplex virus (HSV) infection is the most common cause of corneal ulcer in the United States. Although not always present, the classic finding in HSV infection is a branching dendritic ulcer.
• Infection with HSV may interfere with corneal sensation, resulting in corneal anesthesia.
• Varicella-zoster virus (VZV) can cause a corneal ulcer. Although corneal involvement can occur in varicella (chickenpox), it is uncommon and typically benign. The form of zoster (shingles) involving the ophthalmic branch of the trigeminal nerve is a more common corneal infection caused by VZV.
• When herpetic eruption occurs along the nose, the nasociliary branch of the ophthalmic nerve is involved, indicating that corneal involvement is likely. This is known as the Hutchinson sign.
• The dendritic pattern seen in HSV infection is not seen with zoster infection, although pseudodendrites, which only vaguely resemble true dendrites, may be present. Loss of corneal sensation is a prominent feature of zoster infection.
• In contrast to the usual benign course in varicella and HSV, corneal complications in ophthalmic zoster can be severe and blinding.
• Superficial punctate keratitis is characterized by destruction of pinpoint areas in the outer layer of the corneal epithelium is associated with adenoviruses.
• Bacterial infections
• Numerous bacteria have been reported to cause corneal ulcer, although staphylococcal species, P aeruginosa, Streptococcus pneumoniae, and Moraxella species are reportedly the most common causes in the United States.
• Clinical characteristics of corneal ulcers caused by various bacteria are not sufficiently distinct to determine the causal bacterial agent, although a corneal ulcer having a bluish or green mucopurulent discharge is almost pathognomonic for P aeruginosa.
• Most corneal ulcers are centered, but some occur at the periphery of the cornea (ie, marginal ulcers).
• Although the location of the ulcer does not correlate well with the causative organism, a marginal ulcer is more likely to occur as a result of staphylococcal blepharoconjunctivitis. This ulcer is not due to direct bacterial infection but rather is an inflammatory reaction to staphylococcal bacterial antigens and toxins. The ulcer usually is self-limited and lasts from 7-10 days, but it is likely to recur unless the underlying blepharoconjunctivitis is treated.
• Fungal infections: Fungal ulcers are caused by Candida, Fusarium, Aspergillus, Penicillium, Cephalosporium, and mycosis fungoides species.
• Acanthamoeba keratitis
• Peripheral ulcerative keratitis, associated with rheumatoid arthritis, relapsing polychondritis, and Wegener granulomatosis
• Photokeratitis (snowblindness) is caused by excess exposure to UV light. This can occur with sunlight, suntanning lamps, or a welding arc.
• Sulphur mustard chemical keratitis

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