Diagnosis and Treatment Of Corneal Ulcers
BY TIMOTHY MCMAHON, OD
A patient who normally wears soft lenses walks into your office complaining of a painful red eye since yesterday. On examination you find a 1.5mm x 1.5mm epithelial defect with underlying
infiltrate 2mm from the temporal limbus. You see sectorial limbal injection and a few cells in the anterior chamber. The patient's vision pinholes to 20/25. There is a watery discharge, and the overall conjunctiva looks a little edematous, as do the eyelids of the affected eye I have just described a corneal ulcer. Using your clinical judgement you suspect it is infectious. How will you manage it? Below is a simple set of rules to help you through the problem.
Rarely sight-threatening ulcers are characterized by the presence of each of the following conditions: an anterior chamber response of 1+ or less (<10 cells per 1mm field); a corneal infiltrate of 2mm or less in size; and a corneal infiltrate of >3mm from the visual axis.
Potentially sight-threatening ulcers have any one of the following features: an anterior chamber cellular response of 2+ or greater (>10 cells per 1.0mm field); a corneal infiltrate of >2mm in size; a corneal infiltrate of <3mm from the visual axis; or if the patient's signs and symptoms are worse after 48 hours of treatment.
For those cases designated as rarely sight threatening, it is reasonable to forego culturing the cornea and begin monotherapy antibiotic treatment. A fluoroquinolone is a good choice here. A loading dose of one drop every 15 minutes for two hours, followed by hourly administration around the clock, with an office follow-up visit in 24 hours is a widely-accepted practice. There may be some worsening at the 24-hour mark as the antibiotic is killing the bacteria and releasing more toxins into the corneal tissue. Marked worsening should raise a red flag for inadequate therapy. Daily follow-up until the epithelial defect is healed is prudent.
For potentially sight-threatening ulcers, referral to a trained cornea specialist is the most common practice by optometrists and ophthalmologists, in my experience. If you elect to treat the patient, Gram stains and culturing of the ulcer are prudent tests to run. Following this, using dual antibiotic therapy often with fortified antibiotics is generally preferred. Historically, fortified Ancef, (cefazolin sodium, Abbott) and fortified tobramycin have been the most prevalent drugs. However, using fluoroquinolones in place of Ancef is becoming common unless Pneumococcus is considered as the culprit. Dosing is around the clock with one drug on the hour and the other drug taken on the half-hour. Barring concerns about perforation or the patient's ability or likelihood to comply with the regimen, hospitalization is not normally needed. A 24-hour follow-up visit is required.
Healing the epithelial defect is your first major goal, followed by subsequent reduction of the infiltrate and anterior chamber response. Add a cycloplegic from the start. The surrounding edema and injection resolve concurrently with the corneal ulcer. When the epithelial defect has closed, a steroid can be added to reduce the intensity of the scarring. Keep in mind not all infections are bacterial. Fungal infections and Acanthamoeba can mimic bacterial infections, particularly early in the game.
Our case above would meet the rarely-sight threatening classification, directing you to begin a single antibiotic and a cycloplegic. In most cases, with today's antibiotics your patient will have a scar as a memento, but otherwise will do fine.
Dr. McMahon is a professor and Director of the Contact Lens Service at the University of Illinois at Chicago Dept. of Ophthalmology & Visual Sciences.