"Type of Soap, UV Light Boost Incidence Of DLK"
by Robert M. Kershner, MD, FACS
Tucson, AZ – Diffuse lamellar keratitis (DLK) is a relatively new complication of LASIK that still confounds clinicians. Also referred to as the "sands of the Sahara" syndrome, DLK is a diffuse sterile accumulation of interface inflammatory cells.
Robert Kershner, MD, set out to determine the etiology of the disorder and found the presence of ultraviolet light and New Palmolive detergent to be culprits. Dr. Kershner, who is in private practice in Tucson, AZ recounted how he reached that conclusion.
DLK was not an issue when automated lamellar keratoplasty (ALK) was performed, he explained.
Today, however, DLK is a hot topic, and with the popularity of LASIK, there is speculation about numerous etiologies of the disorder that range from meibomian secretions to operation room temperature changes, he said.
"Prevention consists primarily of avoiding potential contaminants that can cause it, which is difficult because the etiology of DLK is still unknown. The treatment has been just as difficult," Dr. Kershner said.
In an effort to eliminate as many possible etiologies of DLK as possible, Dr. Kershner conducted a prospective evaluation of 682 eyes that underwent LASIK.
The procedure was simplified such that the only things that came in contact with the study eyes were the topical anesthetic, the microkeratome the forceps for lifting and replacing the flap and the laser. At the end of the procedure, the eyes were irrigated with cold BSS.
Dr. Kershner reported that Bausch & Lombs Hansatome and the Automated Corneal Shaper microkeratomes were used interchangeably, with no differences in the incidence of DLK.
"The incidence varied from 0.2% to 3%" he said. "The cases were typically clustered; they were not limited to the first case of the day, the first eye or the surgeon who performed the procedure.
"Only two predisposing factors were identified: ultraviolet light, that is, either the light from the excimer laser or sunlight, and Palmolive detergent, which was used to clean the microkeratome," he said, "When we eliminated the detergent the incidence of DLK decreased."
For DLK to occur there must be both a predisposing factor and a contaminant present. Any soap or detergent may be a factor; Surgeons and staff must be vigilant to prevent outbreak of DLK, according to Dr. Kershner.
"LASIK surgeons should report the incidence and possible etiologies so we than share information about this frustrating complication, because it can be eliminated." Dr. Kershner said.
The New Palmolive detergent is three times as concentrated as that used when ALK was performed, yet we have not adjusted to using only one-third as much," he said. He questioned why surgeons are using the detergent in clean the instrument.
Avoid contact with eyes, he warned, and if contact does occur, rinse the eyes thoroughly with water because any exposure may cause irritation.
"Ultraviolet light, which is not possible to eliminate, does predispose to the exposure that must be present for DLK to occur, he concluded. "Using chilled BSS may reduce or dilute the contaminant and prevent thermal injury. Patients should wear ultraviolet protection postoperatively, because sunlight may be a factor as well."
Dr. Kershner has no proprietary interest in any aspect of this report. He recognized the contribution of David Dulaney, MD, to the study.