Corneal ulcer versus corneal abrasion

I recently had a patient with what I thought was a huge corneal ulcer. According to the ophthalmologist who saw the patient, it was actually just a very large corneal abrasion. How do you distinguish a corneal ulcer from an abrasion? Quick review:

Corneal abrasion
A corneal abrasion occurs when the corneal epithelium is damaged from causes such as fingernail scratches, contact lens wear, and foreign objects. The epithelium is richly innervated so corneal abrasions are usually very painful, but onset of pain can be delayed several hours after injury. Symptoms include foreign body sensation, photophobia, and tearing. Vision is usually normal unless the abrasion is in the central visual axis or if there is associated iritis. Slit lamp exam with the cobalt blue light reveals fluorescein uptake in the region of the corneal defect. If the abrasion is > 24 hours old, cell and flare from iritis may be present. However, there is no infiltrate.

Figure 1.  Corneal abrasion

Treatment goals include relieving symptoms and preventing secondary infection. Cycloplegics relax the ciliary body and relieve pain from spasm.  Narcotic pain medicines may be required for analgesia. Do not prescribe topical anesthetics, as they inhibit corneal healing and inhibit the normal corneal protective reflex of blinking when something gets in the eye. Topical antibiotics should be prescribed--erythromycin ointment (for organic source), ciprofloxacin/ofloxacin/tobramycin for contact lens users to cover for pseudomonas.

Patients with very large corneal abrasions should have ophthalmology follow-up within 24 hours; others can follow-up within 48-72 hours.


Corneal ulcer
A corneal ulcer refers to infection of the various layers of the cornea. Corneal ulcers develop when a break of the corneal epithelium results in microbial access to the underlying corneal stroma. Breaks in the corneal epithelium can be caused by trauma, desquamation, or direct microbial invasion. Contact lens use is associated with increased risk of ulcers, particularly caused by Pseudomonas aeruginosa. S. pneumoniae is another common cause of corneal ulcers. Viruses and fungi are causes of corneal ulcers in the setting of immunosuppression.


Figure 2.  Corneal ulcer caused by herpes virus with dendritic lesions

Symptoms include redness, pain, foreign body sensation, photophobia, and blurry vision. Visual acuity may be decreased if the ulcer is in the central visual access or if uveal tract inflammation is present. Pupillary constriction and consensual photophobia may be present due to ciliary spasm. Examination of the corneal reveals a whitish infiltrate (WBCs in the corneal stroma) and sometimes heaped-up edges of the ulcer. On slit-lamp exam, cell and flare and occasionally hypoypon (WBCs in anterior chamber) may be present.

Corneal ulcers are an emergency and patients should be seen by ophthalmology the same day. Treatment includes antibiotic eye drops and cycloplegics. Corneal ulcers should not be patched because of risk of worsening ulceration and perforation


[From Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7th Ed. Tintinalli, JE, Ed, et al. New York: McGraw Hill, 2011: 594-596]