History
The history may suggest an etiology and may reveal clues concerning the likelihood of an infectious etiology.
Important questions include the following:
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Symptoms
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Contact lens use; sleeping in contacts
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Trauma
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Medications
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Medical history
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Surgical history
Symptoms
Symptoms may include any of the following:
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Erythema of eyelid and conjunctiva
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Mucopurulent discharge from eye
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Foreign body sensation (suggests an epithelial defect, which is suggestive of a bacterial etiology)
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Decreased vision
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Light sensitivity
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Pain
Contact lens use
Contact lens use, including the following: [6]
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Type of contact lens (soft, hard, daily, extended wear)
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Type of contact lens solution
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Contact lens hygiene
Medication use
Current medications, including systemic and especially ocular medications, particularly steroids
Past medical history
See the list below:
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History of ocular disease or eye surgery
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Diabetes mellitus
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History of HIV or other immunodeficiency disorder
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Exposure to sulphur mustard [7]
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Tear-film deficiencies
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Collagen vascular diseases (eg, Wegener granulomatosis rheumatoid arthritis [RA])
Social history
Smoking is an important risk factor.
Physical
The physical examination findings may suggest an etiology, including the likelihood of an infectious etiology.
In addition, a careful physical examination is necessary to assess severity, ie, the risk of perforation and the risk of vision loss.
The physical examination should include measurement of visual acuity, external examination, and slit-lamp examination. [8]
Visual acuity
Visual acuity should be tested at triage, and, if in doubt, the physician should repeat the measurement personally. 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.
Gross examination
Gross examination should include the eyelids, surface of the eye, pupils, extraocular muscles, and fundi. Examination of the lids and the conjunctiva may reveal associated inflammation in these locations. The eye is often erythematous, and ciliary injection is often present. Pupillary constriction may be present secondary to ciliary spasm and iritis. Purulent exudate may be seen in the conjunctival sac or on the surface of the ulcer, and infiltration of the stroma may result in a whitish opacity of the cornea.
Slit lamp examination
Slit lamp examination should follow gross examination in all suspected cases.
Clinical features suggestive of bacterial keratitis include suppurative stromal infiltrate (particularly >1 mm) with indistinct edges, edema, and white cell infiltration in surrounding stroma. An epithelial defect is typically present. An anterior chamber reaction is often seen. [8] The ulcer often is round or oval, and the border is generally 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.
Slit-lamp examination should include assessment of the following: [8]
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Corneal epithelium, including defects and punctate keratopathy, edema
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Corneal stroma, including ulceration, thinning, perforation, and infiltrate (location [central, peripheral, perineural, surgical, or traumatic wound], density, size, shape [ring], number [satellite], depth, character of infiltrate margin [suppuration, necrosis, feathery, soft, crystalline], color), edema
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Corneal endothelium
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Corneal (or scleral) foreign bodies
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Signs of corneal dystrophies (eg, epithelial basement membrane dystrophy)
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Previous corneal inflammation (thinning, scarring, or neovascularization)
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Signs of previous corneal or refractive surgery
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Anterior chamber for depth and the presence of inflammation, including cell and flare, hypopyon, hyphema
Fluorescein staining of the cornea
Fluorescein staining of the cornea is usually performed and may provide additional information about other factors, such as the presence of dendrites, pseudodendrites, loose or exposed sutures, foreign body, and any epithelial defect. [8] Fluorescein staining may reveal characteristic findings, such as the dendritic ulcer of herpes simplex virus infection.
Additional tips
Always examine the contralateral eye.
In a patient who cannot sit up in a slit lamp, and a portable slit lamp is not available, a Wood lamp may be the only available tool for fluorescein examination.
Causes
Although some corneal ulcers are sterile, most are infectious in etiology. Risk factors for corneal ulcer include contact lens use, HIV infection, trauma, ocular surface disease, and ocular surgery. [1] Overnight contact lens wear has been shown to be associated with an increased risk. Other identified risk factors include older age, male gender, smoking, low socioeconomic class, and inadequate contact lens hygiene.
Bacterial keratitis
Bacterial infection is the most important etiology to exclude in the ED. Corneal infections and infectious keratitis are often presumed to be bacterial until proven otherwise.
Bacterial corneal ulcer
Bacterial corneal ulcers may follow a 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 ulcers, particularly due to Pseudomonas aeruginosa. [1]
Bacteria that can penetrate through intact corneal epithelium include Corynebacterium diphtheriae, Haemophilus influenzae, Neisseria gonorrhoea, Neisseria meningitidis, and Listeria species.
Common bacterial isolates cultured from patients with keratitis include P aeruginosa, coagulase-negative staphylococci, S aureus, S pneumoniae, and Enterobacteriaceae (including Klebsiella, Enterobacter, Serratia, and Proteus). K 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.
Viral corneal ulcer
Corneal ulcers due to viral infection often occur on a previously intact corneal epithelium.
Herpes simplex and varicella-zoster viruses can both cause significant infectious keratitis. [2]
Fungal and parasitic corneal ulcer
With the introduction of topical corticosteroid drugs in the treatment of eye disease, fungal corneal ulcers have become more common. Fungi (Fusarium and Candida species) and parasitic amoeba (Acanthamoeba) have been found in a small number of patients and frequently present with more severe symptoms.
Complications
The complications of corneal ulcer can be devastating. Corneal perforation, although rare, can occur. Corneal scarring may develop, resulting in partial or complete loss of vision. Anterior and posterior synechiae, glaucoma, and cataracts also can develop.
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Peripheral ulcerative keratitis in the right eye of a patient with rheumatoid arthritis. Glue has been placed.
