Wiler, Jennifer L. MD, MBA
A 32-year-old woman complains of three days of severe left eye pain, photophobia, burning, and tearing. She says it feels like “something is stuck in her eye.” She denies trauma, fever, headache, or immunocompromising conditions.
She wears contacts but took them out two days earlier. Here is what you see on examination.
What is your diagnosis, and how would you treat this condition? See p. 14.
The cornea is a transparent membrane of five cell layers (corneal epithelium, Bowman's layer, stroma, Descemet's membrane [or posterior limiting membrane], endothelium from anterior to posterior) that cover the anterior portion of the eye including the pupil, anterior chamber, and iris. It communicates with the sclera at the corneal limbus.
The cornea is approximately 0.5 mm to 0.8 mm thick from the center to the periphery, and because of its transparent nature, it has no blood supply but does have unmyelinated nerve cells (via the ciliary nerves from the ophthalmic division of the trigeminal nerve), making it extremely sensitive to touch and temperature.
A corneal ulcer (ulcerative keratitis) is the result of an inflammatory or infectious process that disrupts the corneal epithelium (superficial) and stroma (deep ulcer). Deep ulcers can result in scarring or corneal perforation. Common etiologies include trauma, chemical injury, contact with vegetable matter, contact lens use, dry eye (keratoconjunctivitis sicca), and infection (superinfection related to dry eye condition, herpes).
Autoimmune conditions include rheumatoid arthritis (Z Rheumatol 2010;69:403) and lupus. Wegener's granulomatosis can cause corneal ulcers, which can be the first manifestation of the underlying illness. Rarely cataract surgery, inflammatory bowel disease and idiopathic (Mooren's ulcer) etiologies result in corneal ulceration. Corneal ulcers can be caused by myriad infectious pathogens including bacterial, viral, fungal, and protozoan agents. Bacterial and herpetic infections are the most common in the immunocompetent patient.
Corneal ulcers are most common in contact lens wearers but are still a rare complication (<1%). Those who sleep in contact lenses are reported to be at an eight percent increased risk of developing an ulcer. (Clin Exp Optom 2005;88:232.) Ulcers are also more common in the tropics (Med Trop [Mars] 1995;55[4 Pt 2]:445) and those with vitamin A deficiency (malnutrition, secondary to cirrhosis, cystic fibrosis, celiac or pancreatic disease). One report found that microbial keratitis, a risk factor for development of corneal ulcers, is 10 times more common in India than the United States. (Ophthalmic Epidemiol 1996;3:159.)
Patients with corneal ulcer present with significant unilateral eye pain due to nerve exposure, photophobia, redness, burning, discharge or tearing, photophobia, decreased or blurred vision, and foreign body sensation.
The diagnosis is clinical with direct visualization on slit lamp examination of a white, typically round or oval lesion on the cornea, in a patient with red injected sclera. There may also be signs of anterior uveitis (aqueous cells and flare) or hypopyon in advanced cases. Pupillary constriction is common because of ciliary spasm, and may make examination of the anterior chamber challenging without the use of cycloplegic medications. Fluorescein staining may be helpful to delineate the ulcer margins, which will appear green with blue light illumination. (Photo.) The most common infectious cause of corneal ulcer in the United States is herpes simplex virus, which may produce a classic dendrite lesion pattern. Visual acuity, intraocular pressure (except when corneal perforation is suspected), and a thorough ocular physical examination should be performed.
The evaluation of a corneal ulcer also should include identifying the underlying etiology if one exists. Most commonly related to improper contact lens hygiene, identification of known or new underlying systemic etiologies is prudent. Identification of a new or known immunocompromising condition also should be considered in the evaluation (diabetes, HIV).
Corneal ulcer is considered an ophthalmologic emergency because of the risk for corneal perforation and ruptured globe, and emergent ophthalmologic consultation is indicated. If the etiology of the ulcer is infectious, identification of the underlying pathogen can be important to guide treatment (fungal vs. bacterial). Corneal scrapings and culture may be required to identify the underlying pathogen. Treatment is usually directed by the ophthalmologist, and typically involves broad-spectrum topical antibiotics or antivirals if herpes is suspected and cycloplegic drops. Oral analgesia is typically required until the ulcer improves or resolves.
Patients with an ulcer associated with contact lens should be instructed to stop wearing the lens until cleared by the treating ophthalmologist. Prompt close ophthalmology follow-up should be arranged. Corneal perforation is a rare but potentially devastating complication of corneal ulcer because it can be vision-threatening. (Surv Ophthalmol 1989;34:47.) Glaucoma, synechiae, cataracts, and corneal scarring are also other known complications.
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