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Caution on LASIK flap rhexis
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Editor’s note: Due to a clerical error at the Ocular Surgery News editorial office, the following cautionary comment by Chief Medical Editor Richard L. Lindstrom, MD, was left out of the article, “Innovative procedure deals with sands of the Sahara syndrome at its most advanced stages” (August 15, 2000 issue, pages 1 and 44).
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Sands of the Sahara syndrome, or diffuse lamellar keratitis (DLK) as it is more commonly called, is an exaggerated interface inflammation following lamellar refractive surgery. While all laser in situ keratomileusis patients on careful examination have a few white blood cells in the interface on the first postoperative day, in DLK there is a continuous sheet of cells. These are most commonly seen in the periphery of the flap, especially superiorly, and always are seen under an epithelial defect (stage 1). Most patients respond to topical steroids. We recommend 1% prednisolone acetate hourly.
Most cases respond spontaneously, but others progress with the interface infiltrate migrating centrally (stage 2), then coalescing and clumping (stage 3). At stage 3, there usually is associated corneal edema, reduction in visual acuity and photophobia. Stage 3 DLK responds best to lifting the flap, irrigating the inciting antigen and inflammatory cells from the interface, replacing the flap and treating hourly with 1% prednisolone acetate. Some surgeons also treat with oral steroids (60 to 80 mg per day).
I never have seen a case treated in this fashion progress to stage 4, which is associated with more severe corneal edema, flap melting and necrosis, eventual interface scarring and consecutive hyperopia with regular and irregular astigmatism. The key to treatment is early recognition, intense topical steroids and timely flap lifting and irrigation in progressive cases.
The concept of removing epithelium and Bowman’s layer in a rhexis fashion seems an unusual and aggressive therapy to me. I would be concerned with superficial haze. In a case where the DLK progresses in spite of flap lifting and irrigation, I would recommend a second lifting with more aggressive irrigation and cleaning of the interface. The flaps can safely be lifted multiple times without complication.