Welcome to Eurotimes

Dermot McGrath
in Rome

RECENT upgrades on the Hansatome (B&L Surgical), in particular the development of a series of zero compression heads, have increased the versatility and safety of this popular microkeratome, Thomas Kohnen MD said.

Thomas Kohnen

“We all know the dangers resulting from large epithelial defects. Our studies indicate that serious complications such as diffuse lamellar keratitis (DLK), delayed corneal wound healing and visual recovery, persistent reduced BCVA and recurrent erosions could perhaps be avoided by using a zero compression microkeratome which won’t rub off the epithelium,” he explained.

Dr Kohnen reported that the results of a recent prospective, randomised study carried out in Frankfurt, Germany underscored the difference in performance between the standard Hansatome microkeratome head and the new zero-compression model. In a study involving 93 patients with a mean age of 40 years, 186 eyes were treated with a standard compression head in one eye and the zero-compression head in the other.

Patients with a history of recurrent basal membrane dystrophies or recurrent corneal erosion were excluded from the study. Intraoperative evaluation of epithelial defects was conducted using a standardised protocol.
Of the 93 patients enrolled on the study, 21 (22.6%) treated with the standard Hansatome head showed epithelial defects intraoperatively, compared with two (2.2%) treated with the zero-compression head.

Of the epithelial defects in the standard head group, 15 were larger than 1.5mm and the rest smaller than 1.5mm, while the two recorded for the zero-compression head were both smaller than 1.5mm. Dr Kohnen said that the two eyes with the smaller epithelial defects in the zero-compression head group also had an epithelial defect with the normal Hansatome head.
The study found a statistically significant difference in terms of the incidence (P=0.00004) and size (P=0.0002735) of epithelial defects using the two different Hansatome devices.

“We showed that this new head design significantly reduces the occurrence of epithelial defects. Since we have started to use the zero-compression head in our surgical practice, we have not really found any major problems with epithelial defects of the sort that we were used to seeing with previous versions of the device.

“We have performed Lasik surgery on around 500 more eyes using the zero-compression head and did not experience any problems. I think this is very much a non-issue for us from now on,” Dr Kohnen said.
Stephen Slade MD, FACS echoed Dr Kohnen's assessment of the benefits to be gained from using zero compression heads. In his experience, he said not only did the new heads reduce epithelial defects but also cut consistently thinner flaps.

“We had the good fortune to get the first zero-compression heads made in the US and I agree very much with Dr Kohnen that they do reduce epithelial defects. We didn't do a randomised prospective trial, but we did use the zero-compression heads on 30 consecutive eyes. We very carefully measured intraoperative pachymetry and found they do cut consistently thinner flaps,” Dr Slade said.

He added that he had initially used a combination of compression heads but found that the zero-compression device gave consistently better results.
“We used both Hansatome heads for a while and found that that if we had one eye which had an epithelial defect in it using the standard Hansatome, we would then switch to a zero-compression head on the other eye, where we typically wouldn't get an epithelial defect.

“And as most surgeons are aware, if you get an epithelial defect in one eye using the same compression head, you almost always get another epithelial defect in the exact same mirror image position in the other one. I've been impressed with the improvement,” Dr Slade said.
Dr Kohnen offered some pearls for reducing epithelial defects during Lasik procedures, saying that he has found it better not to use Betadine during surgery in topical anaesthesia.

“We use preservative-free eye drops and we only use them twice and very shortly before surgery. We also think that it’s vital to very carefully check the microkeratome blade. We always use only one blade per eye, so we change the blade for the second eye and check the blade after the microkeratome has been assembled.
“Using these techniques, in conjunction with the zero-compression Hansatome, has really reduced the incidence of epithelial defects to almost negligible levels,” Dr Kohnen said.

Thomas Kohnen MD
Johann Wolfgang Goethe-University, Frankfurt, Germany
Email: kohnen@em.uni-frankfurt.de

Stephen G Slade MD, FACS
VisionTexas, Houston, Texas, US
Email: sgs@visiontexas.com

Top