Skipping second-pass suction reduces epithelium-related trauma in LASIK

Identifying pre-existing corneal abnormalities is the best way to avoid epithelium-related LASIK complications.

Issue: February 1, 2001

ByRochelle Nataloni

NEW YORK — Epithelium-related complications can be serious sequelae of LASIK, but careful preparation can prevent or minimize the effects of these events. LASIK specialist Richard J. Duffey, MD, addressed epithelial problems here at the Ninth Annual Ocular Surgery News Symposium.

“Though not necessarily the last frontier of LASIK surgery, epithelial problems certainly are an area where we need more expertise and further improvement if we are to minimize LASIK complications,” Dr. Duffey said.

Dr. Duffey used the old adage “proper prior planning prevents poor performance” to emphasize the importance of choosing patients wisely to avoid candidates with pre-existing disease. Preventing epithelial trauma, he said, can be as simple as minimizing the use of toxic eye drops such as anesthetics and nonsteroidal anti-inflammatory solutions during LASIK.

“You should aim to minimize any sort of trauma on the cornea. Something as simple as putting the lid speculum in or taking it out can dislocate a flap,” he said.

The microkeratome pass is rife with possibilities for epithelium problems. “We all know we get certain shearing forces that are probably made worse by a dry pass,” said Dr. Duffey. To avoid this, he uses preservative-free artificial tears to achieve a “very wet surface” before the microkeratome pass. “I also routinely isolate the lashes now, too. I use Tegaderm just on the upper lid,” said Dr. Duffey. “For a nasal hinge, the upper lid seams to be the major one that gets in your way.” To minimize trauma, Dr. Duffey rarely touches the corneal surface. He avoids corneal markings and takes extreme care with intraocular pressure checks, drop or bottle tips, Merocel sponges and forceps.

Drying forces are also a major cause of epithelial-related LASIK complications. “When I lay these flaps open, I try to make sure that they are laid out very smooth, and hopefully are equally hydrated on whatever surface they are being placed upon,” he said.

Lip service

Recognizing and treating epithelial abnormalities can minimize complications. An epithelial lip, or the folding back of epithelium on the outer edge of the flap gutters and slides, can be avoided, said Dr. Duffey. To treat an epithelial lip, he explained, minimize extension during painting and place the lip into its normal position with a moist sponge before drying and removing the lid speculum. “This is not a major problem,” said Dr. Duffey, “but you just want to make sure that you don’t let these things extend any further, and make sure that they’re put back in place during the surgery.”

Dr. Duffey described an epithelial slide as loose attachments of epithelium within the flap to the underlying basement membrane causing a slip and stretching of epithelium without tearing. He treats this by tamping the epithelium back into its normal position with a moist sponge and/or forceps before lifting it to proceed with the laser treatment. “Minimize painting to prevent an epithelial slide from turning into an epithelial tear,” he said. If the slide is extensive, the patient may benefit from a bandage contact lens. If the slide involves central corneal overlying the visual axis, the surgeon should expect the patient’s visual acuity to be affected for several days or longer, making a strong case for not operating on the second eye until visual rehabilitation has been achieved in the first, he said.

Dr. Duffey described an epithelial tear as a frank rent and separation of epithelium from surrounding epithelium, often overlying an epithelial slide. He minimizes the extent of the tear by limiting its manipulation and attempting to piece the epithelium back into its normal position before the flap is lifted and upon completion of the flap replacement. “Drying the epithelium into place with an air or oxygen cannula can be helpful,” Dr. Duffey said. “A bandage contact lens should be placed before removal of the lid speculum. The lens may need to remain in place for several days following the LASIK procedure.”

Epithelial problem prophylaxis

Blade inspection is important, Dr. Duffey said, but the change in his practice that has yielded the greatest outcomes improvement has been releasing the suction before the return pass of the microkeratome blade. “Regardless of what microkeratome you use, as it goes across a cornea that is being sucked up into the ring, you’ve got a shearing force going one way and then a shearing force coming back the other way. If you could minimize that by turning your suction off before you bring it back the second time, you basically have half the shearing force. I have seen a significant reduction of probably about 75% in epithelial-related problems since I’ve made that one change,” said Dr. Duffey.


Punctate epithelial keratitis (left) and recurrent erosions (right) are possible epithelium-related complications of LASIK.
Secondary diffuse lamellar keratitis can appear because of white blood cells and edema under abnormal or absent epithelium.	Flap striae can usually be smoothed following LASIK.
Epithelial ingrowth and infectious keratitis can be serious complications of LASIK.	A slipped flap can be treated by smoothing it back into place.
To treat an epithelial lip, the lip is placed into its normal position with a moist sponge before drying and removal of the lid speculum.	An epithelial slide occurs when loose attachments of epithelium within the flap to the underlying basement membrane cause a slip and stretching of epithelium without tearing.
The extent of an epithelial tear can be minimized by limiting manipulation and attempting to piece the epithelium back into its normal position.

Treatment of an epithelial slide requires tamping the epithelium back into its normal position with a moist sponge and/or forceps before lifting it to proceed with the laser treatment.

Treatment of an epithelial defect involves smoothing and stretching the surrounding epithelium to minimize the defect. A bandage contact lens is placed on all defects.
Celluvisc is used on all patients after flap painting and smoothing.

For Your Information:

Richard J. Duffey, MD, can be reached at 2880 Dauphin St., Mobile, AL 36606; (334) 473-1900; fax: (334) 470-8941. Dr. Duffey has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.