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Microkeratome creates both lamellar and epi-LASIK flaps, study finds
In an epi-LASIK study, most surgeons rated quality of final flap “excellent” or “satisfactory.” Patients rated pain as low.
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The Amadeus II microkeratome from Advanced Medical Optics is suited for both LASIK and epi-LASIK flap creation, according to a surgeon who has evaluated the device.
“The Amadeus II not only performs lamellar keratectomies, but it also performs epi-LASIK, or epithelial flap keratectomies,” said Y. Ralph Chu, MD, a cataract and refractive surgeon in private practice in Edina, Minn. The Amadeus II is an upgrade of the Amadeus I microkeratome, he said.
“It maintains all the advantages of the Amadeus I: one-piece design, no on-eye assembly and customizable features,” Dr. Chu said. But in addition, the handpiece of the Amadeus II is 65% less bulky than the original Amadeus handpiece, with improved ergonomics for the surgeon, he said.
“The new handpiece is easier to manipulate and is well-balanced on the eye. There is no difference between left and right eye assemblies. You also have a protective space, which I think is crucial to performing safe keratectomies,” he said.
Dr. Chu and colleagues evaluated the AMO device in creation of both epi-LASIK and LASIK flaps. He reported results of the two separate multicenter studies at the annual meeting of the American Academy of Ophthalmology in Chicago.
LASIK study
The LASIK blades for the Amadeus microkeratomes are labeled with the mean flap thickness, “so a 140 µm blade holder actually cuts a 140 µm flap, plus or minus the standard deviation,” Dr. Chu said.
The study evaluating flap thickness in LASIK flap creation with the Amadeus II included 90 eyes of 48 patients (mean age 37.1 years) at four sites. Using a 140 µm head, the mean flap thickness was 144.5 µm (±20.7 µm), with a range of 111 µm to 203 µm.
He said 43% of eyes were within ±10 µm of target thickness with the 140 µm head, and 76% were within 20 µm.
Epi-LASIK technique
For performing epi-LASIK, an acrylic EpiBlade is used on the Amadeus II keratome, Dr. Chu said. The Amadeus II EpiBlade and EpiBlade holder are specifically designed to lift the epithelial corneal layer, leaving an intact Bowman’s membrane, he said. He described the technique used in the study.
“We use a standard preoperative anesthetic regimen of only two drops of proparacaine,” Dr. Chu said. “A suction ring is placed on the eye to stabilize the globe during the creation of the epi-LASIK flap.” A number of suction ring sizes are available, ranging from 8.5 mm to 9.5 mm in diameter.
“Prior to creation of the flap, copious lubrication of the blade is recommended,” Dr. Chu said. “For epi-keratectomies, the blade travels more slowly across the eye. You set the translation speed at 1.5 mm/second. The oscillation of the blade is 11,000 oscillations/second. There is a standard suction of about 840 mm Hg.” Tonometry is used to check for proper IOP, he said.
“The edges of the epithelial flap are very smooth,” Dr. Chu said. “I think it is important to manipulate the flap as minimally as possible. Using very wet Merocel sponges is the easiest way I have found to manipulate the flap. The biggest pearl I have learned with epi-LASIK is not to use a cannula to manipulate the flap.”
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| Images: Chu YR | |
Epi-LASIK study
The study of epi-LASIK flap creation included 61 eyes. The seven investigators reported no surgical complications, Dr. Chu said.
Surgeons in the study rated the quality of the final flap “excellent” in 66% of cases, “satisfactory” in 30% and “poor” in 4%, he said. The flap fit was rated “excellent” in all cases.
“There was only one case — and it was the second case performed — where there was a slight incursion into Bowman’s membrane,” Dr. Chu said. “That patient did very well.”
After that incident, the amount of suction used was adjusted for the rest of the study, he said, and no further cases of Bowman’s incursion occurred.
Postoperatively, patients rated pain as low (3 or less on a scale of 1 to 10) in 70% of cases at day 1, 87% of cases at day 3, and 100% of cases at day 7.
“Overall, patients experienced significantly less pain with epi-LASIK than you would find on a standard surface ablation with PRK,” Dr. Chu said.
Haze and edema were also low, he said. Edema was moderate in 11 cases on day 1, in four cases on day 3 and in no cases by day 7.
“I think it is very nice that we now have a keratome that can do both lamellar and epi-LASIK flaps,” Dr. Chu said. “The Amadeus II is an easy-to-use unit. It provides consistent flap thickness, excellent flap quality, reliable operation and a comfortable handpiece, with minimal complications.”
For Your Information:
- Y. Ralph Chu, MD, can be reached at Chu Vision Institute PA, 7760 France Ave. South, Suite 140, Edina, MN 55435; 952-835-0965; fax: 952-835-1092; e-mail: yrchu@chuvision.com. Dr. Chu is a paid consultant to Advanced Medical Optics.
- Bob Kronemyer is an OSN Correspondent based in Elkhart, Ind.