THERAPEUTIC FORUM

Stomp Down Hard
On 'Sands of the Sahara'

by Christopher J. Quinn, O.D.

With the increase in popularity and success of LASIK, O.D.s need to get involved in the postoperative comanagement of patients who undergo the procedure. LASIK has offered excellent visual results with few postoperative complications. As more patients have the procedure—almost 500,000 patients in 1999, about double from last year—comanaging practitioners need to recognize and successfully treat the so-called "sands of the Sahara" complication.

Eye surgeon Bobby Maddox, M.D., of El Paso, Texas, coined the picturesque nickname for the syndrome's granular appearance. A more accurate name is diffuse lamellar keratitis (DMK).

Most patients undergoing LASIK have an uneventful postoperative course. Occasionally a patient may experience increased pain, photophobia and tearing 2-6 days after the procedure. Examination at that point may reveal a diffuse, multifocal inflammatory infiltrate at the interface of the corneal flap and bed. The corneal epithelium remains intact, usually without significant anterior chamber reaction. The conjunctiva often remains quiet with no significant increase in injection. The infiltrative haze is limited to the interface and does not extend into the stroma.

Left untreated, the infiltrate can grow toward the central cornea, causing reduced visual acuity and eventually even stromal melting. This may lead to irregular astigmatism and further visual loss.

What's Beneath the 'Sands'?
The refractive surgery community has debated the etiology of DLK. Smears of the interface in patients with this condition have revealed neutrophils, suggesting an allergic or toxic immunologic response. An infectious etiology seems unlikely, since bacteria haven't been isolated in this condition.

A long list of possible inciting agents has been suggested. These include talc from gloves, Staphylococcus antigens, meibomian gland secretions, liquids or grease from the microkeratome, residue on the microkeratome blade, soap residue or contaminants in the irrigating solution. Postoperative medications including steroids or nonsteroidal anti-inflammatory agents have been suspected as well. Some doctors think DLK is more common in patients with a history of atopy or autoimmune disorders.

Hit the 'Sands' Hard
Whatever the cause, you can treat DLK effectively and prevent the loss of best-corrected visual acuity if you recognize the condition promptly and treat it aggressively.

If your patient develops DLK, begin frequent instillation of topical steroids to quell the inflammatory response.

Start the patient on Pred Forte (prednisolone acetate) one drop every 30-60 minutes until the infiltrative haze begins to resolve. You should begin to notice improvement in a few days, although it may take several weeks of treatment for complete resolution.

Once the infiltrate begins to subside, gradually decrease the dose until the corneal interface clears and the infiltrate has resolved.

If you're concerned that the patient has an infectious component—anterior chamber reaction, infiltrate extending into the surrounding stroma—culture the infiltrate and initiate aggressive antibiotic therapy.

Some surgeons recently reported a worrisome central focal interface opacity that can begin as DLK. It's not confined to the interface like DLK, but progresses posteriorly to the epithelium. Patients can lose vision or become hyperopic. The cause of this syndrome is unknown and it doesn't respond to steroids. We need more investigation into this nasty cousin of DLK.

We'll probably see an increase in DLK as clinicians begin to recognize more mild cases. For the most part, prompt recognition and aggressive treatment with steroids will lead to excellent outcomes and patient satisfaction with LASIK.