Low complication rate found with mechanical microkeratomes

Study raises questions of comparison to laser microkeratomes

Even though some physicians promote laser microkeratomes as a safer way to make a flap than with a mechanical microkeratome, other surgeons say when done properly, mechanical microkeratomes are just as safe and effective.
Robert K. Maloney, M.D., director, Maloney Vision Institute, Los Angeles, performed a study by reviewing his past surgeries, evaluating the complications he had, and determining that mechanical microkeratomes are as safe as lasers.
“There is no technology, and there is no tool, that is going to eliminate complications,” Dr. Maloney said. “It’s just not going to happen.”

Performing a self-evaluation

Dr. Maloney said he used the Hansatome microkeratome (Bausch & Lomb, Rochester, N.Y.) exclusively during this period that he reviewed.
In all, Dr. Maloney looked at 16,756 primary LASIK surgeries, starting and ending with a flap complication. This is necessary statistically to get a better incidence, he said.
During that time, Dr. Maloney had 11 flap complications in 11 eyes for a complication rate of one bad flap for every 1,676 eyes. Of those flap complications, buttonholes occurred six times while the rest of the complications were an assortment.
The question Dr. Maloney was looking to answer was how these complications affected patients’ vision.
Dr. Maloney said he had post-op best-corrected visual acuity (BCVA) for nine of the 11 eyes and pre-op BCVA for all 11 eyes. None of the eyes lost even a single line of BCVA, he said.
In all nine eyes with complications that had post-op BCVA measured, post-op BCVA was at least as good as it was pre-op. “So none of these 16,000 eyes lost a line of BCVA because of a microkeratome complication,” Dr. Maloney said.
As for the effect of buttonholes—Dr. Maloney performed post-op refractive surgery on four of the six eyes that had this complication—he said it was interesting that the mean hyperopic shift in these eyes ranged from 0 to 2 D, but there was essentially no change in the astigmatism.
“All of the patients were myopes, so they tended to become a little less myopic,” he said. “So it seems that buttonholes created a minor hyperopic shift without inducing astigmatism.”

Mechanical and laser

During a presentation of his information, Dr. Maloney was asked about eliminating all complications by using a laser microkeratome instead of a mechanical microkeratome.
“When we have something new, everybody is excited, everybody is up,” Dr. Maloney said, but added that new technology just replaces old complications with new complications. In such cases, he said he’s not sure if the technology has accomplishing anything.
In particular, Dr. Maloney addressed comparisons to IntraLase femtosecond laser (IntraLase Corp., Irvine, Calif.). “IntraLase complications are more typically flap tears from dissection or haze following inflammation,” he said.
Dr. Maloney concluded that complications are rare with a mechanical microkeratome because he reported one complication for every 1,676 eyes.
And when properly managed, flap complications affect vision even more rarely, with zero cases out of 16,756 eyes.
“So I do believe the safety of a mechanical keratome is very high, and it sets a very high threshold for alternative devices,” Dr. Maloney said.

IntraLase supporters

But physicians that have switched to IntraLase apparently are happy with their laser keratomes because none have switched back, said Daniel S. Durrie, M.D., Durrie Vision, Overland Park, Kan.
“I haven’t heard anyone give one up yet,” he said. “They haven’t sold it to somebody else and moved on.”
A former Hansatome user himself, Dr. Durrie has reported how he has had a series of 13,243 consecutive cases without a bad flap, but he wanted to know if the laser would provide better vision and more satisfied patients.
Dr. Durrie performed a randomized, contralateral, prospective study using a Hansatome on one eye and using an IntraLase on the other eye. The study was published in the January 2005 issue of the Journal of Cataract & Refractive Surgery.
The IntraLase eye had faster visual recovery, better uncorrected vision, and less dry eye symptoms and findings. Both keratomes were safe, said Dr. Durrie.
“There is nothing wrong with a Hansatome, but we are moving into an era of is this better technology,” Dr. Durrie said. “There seems to be a trend of more physicians making the switch.”
One factor keeping the trend at bay is cost, which is an especially important factor for a low-volume surgeon. IntraLase is a $375,000 machine and there is a $190 per eye procedure fee.
But Dr. Durrie said there are advantages beyond safety because there was less recovery time and the patients could see better faster, among others.
He agreed with Dr. Maloney in so much that bad flaps are reported with both technologies. And while all surgeons aim for no complications, nothing is complication-free. Dr. Durrie said he thinks IntraLase reduces the risk of having a bad flap.
“I don’t use the mechanical microkeratomes anymore because I just don’t need to,” he said.

Editors’ note: Dr. Durrie has performed clinical research for IntraLase Corp. Dr. Maloney is a consultant for Bausch & Lomb.

Contact Information
Durrie: 913-491-3330, ddurrie@durrievision.com
Maloney: 310-208-3937, drmaloney@maloneyseibelvision.com