treatment plan

Epithelial Erosion: A Recurring Problem

BY WILLIAM TOWNSEND, OD
JUNE 1998

Michael presented one morning with intense pain, epiphora and photophobia after his young daughter had accidentally scratched his right cornea with her fingernail. Best visual acuities were OD 20/40; OS 20/20. Slit lamp examination revealed a 3mm by 5mm area of abrasion with loose, jagged margins. The underlying stroma was edematous with numerous vertical folds; the conjunctiva showed grade II+ injection. Cells and flare were present in the anterior chamber. We pressure-patched the eye with a topical antibiotic ointment, and the abraded area re-epithelialized within a few days, although stromal folds and epithelial edema were still present.

A week later, Michael reported pain and blurred vision. The epithelium over the original wound had detached from the underlying tissue, so we debrided the loose epithelium, repatched the eye, and prescribed a long-term course of hyperosmotic drops and ointment. Michael continued to have problems with recurrent corneal erosion (RCE) especially when he failed to use the ointment at bedtime. After several episodes of recurrence, we treated the affected area with corneal micropuncture. After the procedure he still had episodes of RCE, so we referred him for phototherapeutic keratectomy. Since then, he's had no further recurrences.

The Source of the Problem

Forty percent of recurrent corneal erosions occur spontaneously and are associated with corneal dystrophies; sixty percent occur after trauma. Traumatic RCE is usually caused by injuries that tear the epithelium away from the underlying tissue.

After a corneal injury, epithelial cells proliferate and migrate toward the center of the lesion. Fibronectin, a serum glycoprotein, coats the surface of the lesion to form an adhesive layer that bonds the migrating cells to underlying tissue. Then hemidesmosomes develop and strengthen the adherence of the epithelial cells to Bowman's layer. Electron microscopy confirms that areas of RCE are characterized by an absence of or alteration in basement membrane and hemidesmosomes.

Managing RCE

The goals of management are to prevent secondary infection, encourage reformation of normal attachments between epithelium and underlying tissue and to manage pain and inflammation. The traditional approach has been pressure patching with topical antibiotics and, when indicated, steroids. Bandage contact lenses may be used as an alternative to pressure patching. Closed eye conditions lead to epithelial edema, and swollen tissue is more likely to detach from underlying tissue, so hyperosmotics are an essential tool in managing RCE.

Oral NSAIDS are particularly valuable in managing pain associated with RCE. Patients who have been pressure patched, even with antibiotics, are at risk for developing infection, so monitor them frequently, and have them use topical antibiotics after patching has been discontinued. Patients with RCE should continue to use a hyperosmotic ointment at bedtime for several months after re-epithelialization occurs; some patients must use it indefinitely.

Cornea micropuncture bonds epithelium to anterior stroma, and is performed by placing multiple, closely spaced punctures through damaged epithelium into stroma. Consider using sterile forceps to bend the point of a sterile 25 gauge needle away from the bevel so that it is not be more than 0.15mm in length. When applied tangential to the cornea, this device cannot perforate the cornea, causing less scarring than a deeper wound. Although minimal scarring occurs, it is best to avoid performing this procedure on the visual axis.

Dr. Townsend is in private practice in Canyon, Texas, and is a consultant at the Amarillo VA Medical Center.