Palmolive keratome cleaning protocol is a possible aggravating factor for DLK

A changed formulation may have made the soap a cause of diffuse lamellar keratitis in some eyes. Bausch & Lomb has stopped recommending its use.

TUCSON, Ariz. — Diffuse lamellar keratitis is among the least well understood and hardest to treat of LASIK complications. While many in the profession focus on the best ways to treat it, other physicians are looking into what may be causing diffuse lamellar keratitis (DLK).

One possible answer to date — soap. More specifically, Palmolive dishwashing liquid.

Tucson, Ariz., ophthalmologist Robert M. Kershner, MD, performed a randomized prospective study of all his LASIK patients at one laser facility. He looked at more than 1,249 patients. He now believes the Palmolive cleaning protocol formerly recommended by his keratome’s manufacturer may have been a cause of DLK at his facility.

Hansatome care instructions

For years, care instructions for the Chiron Hansatome microkeratome (now a Bausch & Lomb product) included cleaning instructions which stated that “Chiron Vision recommends use of a cleaning solution consisting of 2 parts green Palmolive dishwashing liquid (unconcentrated product) to 100 parts warm tap water.”

However, the Colgate-Palmolive Company, maker of Palmolive, no longer makes the unconcentrated version of the product.

In a faxed statement responding to inquiries regarding their product, Colgate-Palmolive stated, “Our company tests all of its products extensively to be sure they provide consumer satisfaction when used for the purposes described on the label. Sometimes, consumers report that they have good results using a product in other situations or ask if a product can be used in an alternate way. However, we can only recommend that our products be used as tested and described on the label. Since we have not done specific testing regarding surgical equipment, we cannot recommend it for that use.”

Bausch & Lomb recently changed its microkeratome cleaning recommendations, removing Palmolive from the protocol.

The search for a cause

“We literally searched our entire armamentarium looking for causes,” said Dr. Kershner. “I had performed thousands of microkeratome cuts, both with automated lamellar keratoplasty (ALK) and LASIK, and did not see any cases of DLK. Then all of a sudden we started seeing sporadic cases. Many seemed to be clustered, and many appeared at certain times of year, winter and summer.”

He decided to investigate every factor under his control and eliminate each one, one at a time.

“I had been interested in the work of other LASIK surgeons,” he said. “The discussions concerning bacterial biofilms and autoclaves were interesting. But the so-called causes of DLK they reported were for things that I did not use, so I knew it had to be some other factor, and one that most everyone used.”

Dr. Kershner noted that he had always cleaned his keratome with detergent as per the manufacturer’s recommendations quoted above. But he had not seen DLK until recently.

“What was curious was that at about the time we all switched to LASIK and started using our microkeratomes for this procedure, we started seeing this occurrence, but did not see it when we were using our machines for ALK,” Dr. Kershner said. “Ironically, Colgate-Palmolive changed the formulation about this time to sell the consumer less agent, but with three times the concentration, presumably so consumers would still use the same amount but buy more frequently.

“We never noticed the change, except that the agent was much greasier and harder to get off your fingers and instruments. It was this staying power that I think set up the agent as one of the inciting causes of DLK,” he continued.

Dr. Kershner looked at his microkeratome blades under electron microscopy and had them biochemically analyzed. There had been reports of waxes and oils on the blades that caused the DLK reaction, and some suggested that washing the blades in acetone would make it go away. According to him, that didn’t work.

The biochemical analysis of the keratome blades, which were of varying quality, did not show any contaminant that could be extracted and analyzed with gas chromatography. His Hansatome had a contaminant on the blades known as Irganox 183 from a plastic piece of the device. Dr. Kershner said Irganox 183 is an organic substance used in plastic manufacturing.

Rather than simply cutting his Palmolive liquid amount by two-thirds in response to the increased concentration of the product, Dr. Kershner instead chose to remove it altogether as a cleaning agent. He said he suspects that there may be something new in the reformulated Palmolive that was not in the original product.

Dr. Kershner said his procedure now is to clean after every case, and his microkeratomes are no longer soaked. Instead they are scrubbed with distilled water and rinsed, then sterilized with Statim dry sterilization.

B&L changes cleaning procedures

As of January 2001, Bausch & Lomb has changed its cleaning procedure recommendations for the Hansatome and no longer advises the use of Palmolive.

According to Christopher Owens, director of lamellar surgery for the Americas at the company, the changes were in response to recommendations from laser vision correction centers and physicians using the keratomes, as well as improvements in cleaning solutions and strategy.

The new cleaning procedures recommend using a pH balanced enzymatic cleaner. Bausch & Lomb suggests using Klenzyme (Steris, Mentor, Ohio), Enzol or Cidezyme (Advanced Sterilization Products, Irvine, Calif.) to clean the Hansatome.

Kera-Clean, by Micra USA (Utica, N.Y.), is another cleaner surgeons could use. Kera-Clean, according to company officials, does not contain a carbon-based lubricant and cleans instruments without leaving a residue.

In the “frequently asked questions” section of its guide to the Hansatome, Bausch & Lomb says the change from Palmolive to enzymatic cleaners was because they are formulated for medical devices. The company also has made changes to the sterilization parameters for the keratome and suggests surgeons stop sterilizing the old way immediately and begin using the new suggestions.

Bausch & Lomb has also developed a videotape for physicians demonstrating the new cleaning and sterilization procedures. All the new recommendations are available by contacting Bausch & Lomb Surgical. Further, Bausch & Lomb will be sending a new operator’s manual and video to all existing customers.

Not just the soap

Even after his study implicating the soap, Dr. Kershner believes that there may be other contaminants that also incite DLK, such as cleaners, waxes and oils on blades and maybe even gram-negative bacterial cell walls.

But Palmolive and other physical irritants may not be the only factors that cause DLK, Dr. Kershner said. During his studies there was one factor he was not able to remove entirely: ultraviolet (UV) light.

“I am convinced that an abrasion to the cornea and a subsequent ultraviolet burn can also incite the inflammation known as DLK,” Dr. Kershner said. “By a process of elimination I concluded it was UV. Accordingly, we dropped the incidence by having patients avoid UV postoperatively with protective eye wear.”

He also stressed the importance of keeping the procedure as simple as possible. “Use only the minimal number of instruments, reuse as little as possible, and with the addition of cold balanced saline irrigation to the exposed bed and flap, we can almost completely eliminate DLK.”

Dr. Kershner now uses a no-touch technique. He lifts the flap with specially designed forceps (Kershner Lasik Flap Forceps, Rhein Medical), applies the laser, irrigates profusely, flips the flap back and closes the eye.

“This approach has served me well and eliminated the problems we had,” he said.

For Your Information:

• Robert M. Kershner, MD, FACS, can be reached at 1925 West Orange Grove Rd., Ste. 303, Tucson, AZ 85704-1152; (520) 797-2020; fax: (520) 797-2235; e-mail: Kershner@asiteforeyes.com; Web site: www.asiteforeyes.com. Dr. Kershner has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Christopher Owens is director of lamellar surgery for the Americas for Bausch & Lomb Surgical; (909) 399-1388; fax: (909) 399-1363; e-mail: christopher_owens@bausch.com.

• Information on the new recommended cleaning regimen for the Hansatome microkeratome can be obtained from Bausch & Lomb Surgical, 555 West Arrow Highway, Claremont, CA 91711; (909) 624-2020; fax: (909) 399-1525; e-mail: info_blsurgical@bausch.com.