Corneal Ulceration and Ulcerative Keratitis in Emergency Medicine Medication

The first-line regimen in treating corneal ulceration usually consists of alternating an aminoglycoside with a first-generation cephalosporin every 15-30 minutes. Frequently used, ciprofloxacin 0.3%, offers a shorter average time to healing and a reduced duration of therapy than conventional therapy. Obviously, the concern with this type of monotherapy is resistance.

Antibiotics may be administered by subconjunctival injection if compliance is a concern. To reduce the inhibition of corneal regeneration caused by concentrated antimicrobial solutions, the intervals between antimicrobial instillation and/or frequency of instillation should be prolonged following a decrease in purulence and a reduction in ulcer size.

If tests show that a viral infection is present, begin therapy with mechanical debridement of the infected rim along with a rim of the normal epithelium, followed by a topical instillation of the antiviral medications.

In fungal infections, a broad-spectrum antifungal drug usually is chosen. Some of the alternatives include natamycin, fluconazole, amphotericin B, miconazole, and ketoconazole. Natamycin is the first-line treatment in fungal infections of the cornea.^[7]

An adjunctive therapy may be required for conditions secondary to the ulcer. Atropine 1% or scopolamine 0.25% drops can be used to prevent formation of adhesions between the iris and the lens or cornea.

Topical corticosteroid use is controversial because its use in viral infections is relatively contraindicated, but it may prevent corneal scarring and perforation.^[8] Corticosteroids must be tapered to prevent rebound inflammation.

Hyperosmotics, carbonic anhydrase inhibitors, or beta-blockers can be administered if transient increases of intraocular pressure result from the keratitis.

Class Summary

Anesthetics are indicated for pain relief and for conjunctival and corneal scrapings. Local anesthetics stabilize the neuronal membrane and prevent the initiation and transmission of nerve impulses, thereby producing the local anesthetic action.

Proparacaine (Ophthetic, I-Paracaine)

Has a rapid onset of anesthesia that begins within 13-30 sec after instillation. Short duration of action (about 15-20 min). Since prolonged eye anesthesia can eliminate the patient's awareness of mechanical damage to the cornea, do not use outside of the ED. Frequent use of anesthetics may retard healing.

Class Summary

Therapy must cover all likely pathogens in the context of the clinical setting.

Cefazolin (Ancef, Kefzol)

First-generation cephalosporin antibiotic for gram-positive bacterial coverage. Commonly used in combination with an aminoglycoside to achieve broad-spectrum coverage.

This 50-133 mg/mL solution must be compounded.

Gentamicin (Genoptic)

Aminoglycoside antibiotic used for gram-negative bacterial coverage. Commonly used in combination with a first-generation cephalosporin.

Erythromycin (E-Mycin, E.E.S.)

Indicated for treatment of infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections.

Ciprofloxacin ophthalmic (Ciloxan)

Bactericidal antibiotic that inhibits bacterial DNA synthesis, and consequently growth, by inhibiting DNA gyrase in susceptible organisms.

Indicated for pseudomonal infections and those due to multidrug-resistant gram-negative organisms.

Class Summary

These agents are used in the treatment of rheumatoid arthritis associated corneal ulcer.

Infliximab (Remicade)

Chimeric anti-tumor necrosis factor alpha monoclonal antibody. Neutralizes cytokine TNF-alpha and inhibits its binding to TNF-alpha receptor. Mix in 250-mL normal saline for infusion over 2 h. Must use with low-protein-binding filter (1.2 micron or less). Indicated to reduce signs and symptoms of active ankylosing spondylitis.

Class Summary

Instillation of a long-acting cycloplegic agent can relax any ciliary muscle spasm that can cause a deep aching pain and photophobia.

Scopolamine ophthalmic (Isopto Hyoscine)

Blocks the action of acetylcholine at parasympathetic sites in the smooth muscle, producing pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).

Class Summary

Therapy of viral infections begins with mechanical debridement of the involved rim along with a rim of normal epithelium. This is followed by the topical instillation of antiviral medications (eg, vidarabine, idoxuridine, trifluridine).

Vidarabine (Vira-A)

Indicated as a topical idoxuridine or when toxic or hypersensitivity reactions to idoxuridine occur. Appears to interfere with the early steps of viral DNA synthesis.

If no signs of improvement are evident after 7 d or if complete reepithelialization has not occurred in 21 d, consider other forms of therapy. Some severe cases may require longer treatment. After reepithelialization has occurred, treat for an additional 7 d at a reduced dosage (eg, twice daily) to prevent recurrence.

Idoxuridine (Herplex)

Used for epithelial infections (especially initial attacks). Infections characterized by the presence of a dendritic shape respond better to this medication than stromal infections.

Blocks the reproduction of HSV by producing incorrect DNA copies that prevent the virus from infecting or destroying the tissue.

Class Summary

Broad-spectrum antifungal agents that cause minimal pain and corneal irritation are recommended. Natamycin is the first-line treatment in fungal infections of the cornea. Candidal infections refractory to natamycin may respond to amphotericin B, miconazole, fluconazole, and ketoconazole. Topical application of these drugs, however, is somewhat limited because most of them must be compounded.

Natamycin (Natacyn)

Predominantly fungicidal tetraene polyene antibiotic, derived from Streptomyces natalensis that possesses in vitro activity against a variety of yeast and filamentous fungi, including Candida, Aspergillus, Cephalosporium, Fusarium, and Penicillium species. Binds fungal cell membrane forming a polyene sterol complex that alters membrane permeability and depleting essential cellular constituents. Activity against fungi is dose related, but it is not effective in vitro against gram-negative or gram-positive bacteria. Generally, therapy should be continued for 14-21 d or until the fungal keratitis has resolved. In many cases, reducing the dosage gradually at 4-7 d intervals may help ensure that the organism has been eliminated.

Class Summary

Mechanism of action is believed to be through inhibition of the cyclooxygenase enzyme that is essential in the biosynthesis of prostaglandins. Inhibition of prostaglandin synthesis results in vasoconstriction and decreases in vascular permeability, leukocytosis, and intraocular pressure (IOP). These agents, however, have no significant effect on IOP.

Ibuprofen (Ibuprin, Motrin, Advil)

Usually the DOC for treatment of mild to moderate pain, if no contraindications exist.

Inhibits inflammatory reactions and pain, probably by decreasing the activity of the enzyme cyclooxygenase, which results in prostaglandin synthesis.

Class Summary

Pain control is essential to quality patient care, ensuring patient comfort, promoting pulmonary toilet, and containing sedating properties that benefit patients who experience mild or severe pain.

Oxycodone and acetaminophen (Percocet)

Drug combination indicated for the relief of moderate to severe pain.