Two-stage ALTK compares favorably to traditional LK and one-stage ALTK

Surgeon says results are more predictable and there are fewer complications with two-stage vs. one-stage ALTK.

Issue: November 1, 2004

ByBob Kronemyer

Two-stage automated lamellar therapeutic keratoplasty offers advantages over both traditional lamellar keratoplasty and one-stage automated lamellar therapeutic keratoplasty, according to one surgeon.

“The two-stage procedure can be an extremely effective technique to visually rehabilitate patients,” said Richard F. Beatty, MD, a cornea and external diseases specialist in Denver. “Traditional lamellar keratoplasty (LK) has vision limitation because of interface scarring. On the other hand, automated lamellar therapeutic keratoplasty (ALTK), whether one stage or two stage, has less scarring in the interface. Therefore, visual rehabilitation can be excellent. However, one-stage ALTK has a less predictable wound architecture compared to the two-stage surgical procedure.”

ALTK indications include chemical burn, herpes simplex virus corneal scar, and pediatric corneal scar. “Three advantages of one-stage ALTK are that the cost, time and risk are reduced because there is only one procedure,” Dr. Beatty said. “In pediatric cases, there is more risk subjecting the child to two general anesthetic procedures instead of one.”

The disadvantages of one-step ALTK are donor/host flap diameter disparity, donor/host uniform thickness disparity, peribulbar/retrobulbar risks (chemosis) and epithelial ingrowth risk, he said.

Two-stage ALTK

Indications for two-stage ALTK include anterior/midstromal scars, anterior corneal dystrophy and irregular astigmatism (uniform corneal thickness).

Suturing after stage 2 can be running, interrupted or combined.

“Two of the benefits of this two-stage procedure are minimized donor/host thickness disparity with central trephination and predictable wound architecture,” Dr. Beatty said. In adults, the first stage can be performed under topical anesthesia and the second stage often with only local anesthetic.

Disadvantages include the cost, time and risk of two surgical procedures and prolonged visual recovery because of the additional time between the first and second operation.

The first stage of the procedure mirrors LASIK. “We select a vacuum ring, based upon the corneal curvature, in anticipation of the diameter of the host flap we want to prepare,” said Dr. Beatty, who uses the Moria LSK-1 manual microkeratome to create a flap with a nasal hinge. “That flap is repositioned by lifting, irrigating and repositioning.”

“The LSK-1 microkeratome is put into a dovetail track, then moved along the track using a manual technique at a uniform speed,” Dr. Beatty said. “You are creating a hinged flap because of the stop ring.”

Second stage

The time between the first stage and the second stage is 4 to 6 weeks.

The second stage involves making a central corneal trephination with a diameter between 7 and 7.5 mm. “The Moria artificial anterior chamber enables us to do this procedure,” said Dr. Beatty at the annual meeting of the American Society of Cataract and Refractive Surgery. “The artificial anterior chamber secures the corneoscleral rim onto the base of the unit.”

A LeVeen disposable inflation syringe 10 cc (Boston Scientific) is then attached to the base of the artificial chamber. “The inflation syringe is used to increase the pressure inside the artificial anterior chamber using the screw-handle mechanism on the syringe,” Dr. Beatty said. Counterclockwise rotation will loosen the corneal tissue seal, he said.

The donor/host diameter can be 7 mm, 7.25 mm or 7.5 mm. “In most cases they are the same, but may oversize by 0.25 mm,” Dr. Beatty said. For optimal depth of the lamellar graft, “we recommend either the 250 or 300 head with the LSK-1 microkeratome. The thicker the graft, the less tendency for irregular astigmatism,” he said.

The suture method can be running, interrupted or a combination. “The suture technique varies, depending on the experience of the surgeon,” Dr. Beatty said. Sutures are removed 4 to 8 weeks after the second surgery.

In the first stage, a hinged flap is created, similar to a LASIK procedure.	In stage 2, 4 to 6 weeks later, a smaller lenticule is removed from the stromal bed.
ALTK stage 2 involves making a corneal trephination with a diameter of between 7 mm and 7.5 mm.	The diameter of the lenticle is confirmed with an applanation lens (9 mm to 9.5 mm).
Images: Beatty RF

Favorable outcomes

Eye is seen at postop day 1 after stage 1.

Over the past 3 years, Dr. Beatty has performed 22 two-stage ALTKs. “Overall, the results are very satisfactory for vision rehabilitation of anterior stromal scars,” he said. “Compared to one-stage ALTK, results are more predictable and there are fewer complications.”

Among the 22 patients, two had an incomplete flap, one had incomplete excision of donor lenticle, and one had a flap melt (scleroderma). Irregular astigmatism was a common complication, he said.

Dr. Beatty said an automated microkeratome system could eventually replace the manual technique. “The surgeon would no longer need to manually advance the microkeratome on the host or donor tissue preparation,” he said. “There is also a steep learning curve with two-stage ALTK, so surgeons will do well if they share their experience and study the work of other people.”

For Your Information:
Richard F. Beatty, MD, can be reached at 950 E. Harvard Ave., Suite 350, Denver, CO 80210; 303-722-9923; fax: 303-722-0818; e-mail: rfb@coloradoeye.com. Dr. Beatty has no direct financial interest in the products mentioned in this article.
Bob Kronemyer is an OSN Correspondent based in Elkhart, Ind.