spotlight on technology & technique
Building a Better Microkeratome
Bausch & Lomb's Zyoptix XP offers hinge flexibility, reduced flap variability, and enhanced efficiency.
By John Parkinson, Associate Editor

Bausch & Lomb's latest microkeratome, the Zyoptix XP, has its foundation in the Hansatome, including its cutting geometry, but the XP has several new features that take it to the next level.

The XP includes a handpiece that's compatible with all B&L consoles; integrated motor gearbox zero-compression head with no external gears, which eliminates jamming problems; interchangeable components; sterilizable motor sleeve; OS/OD selector switch on the link arm assembly; a blade designed to decrease flap standard deviation; and a system that can deliver various hinge positions.

Procedure

Scott MacRae, M.D., medical director at the University of Rochester Medical Center's Strong Vision clinic, discusses the best new capability of the XP. "The system is designed to make more reproducible flaps; it's the major driving force within this system." B&L reduced the variability in flap thickness by making the blade extension tighter. The distance the blade extends is four times more controlled. Reproducible flaps lead to greater consistency.

Dr. MacRae explains further why this is so useful to his practice. "Let's say you have a Zyoptix XP head that is cutting at 120 microns, and you want to use a different Zyoptix XP set which also has a 120 micron head, it will cut at 120 microns very reliably for the next case. It's a big advantage for surgeons to have a system that can give them enough accuracy so that they can predict that both sets are always going to be around 120 microns," states Dr. MacRae. "The microkeratome's head thickness labeling is based on outcomes from actual human data, which hasn't been the case in the past."

He attributes this consistency of the product to B&L's tight manufacturing specifications. This consistency is also showing up in preliminary studies on standard deviation. While research is still ongoing, Dr. MacRae says the microkeratome is delivering a standard deviation of 10 microns when using the 120 head, which is down from 20 microns. The ability to create very specific manufacturing guidelines leads to a consistent product with lower standard deviations.

Another key feature of the product is the ability to make hinges in various locations. Dr. MacRae believes it's extremely important for the surgeon to have a tool that can create whatever hinge location the surgeon prefers. "With these new systems it's important to have the flexibility to do superior, nasal, or whatever direction people find optimal." The XP's suction ring can be set up to do superior, nasal, or oblique hinges.

Tighter manufacturing tolerances are reducing the variation in the blade extension of the Zyoptix XP.

Other Features

Along with the ability to create reproducible flaps and make various hinges, the XP has a component that adds convenience. The OS/OD Selector switch allows surgical teams to just flip a switch in order to go from working on one eye to another. Technicians no longer have to dissemble the microkeratome, saving time as the transition from one eye to another is made.

Along with instrument components that add flexibility and consistency to the XP, extra safety features were implemented as well. One such feature is the sterilizable motor sleeve. The sterilizable aspect of the sleeve was addressed after the European medical community required that every instrument that touches a patient during the course of surgery must be sterilized.

Another safety feature is the mechanical stop. This stop prevents the microkeratome from moving forward unless it's properly seated upon the eye. The safety stop was designed to decrease flap complications that may result if the unit isn't placed correctly on the eye. However, this set-up is different from the Hansatome, which allows the surgeon to see the pin on the gear track and provides visual clues to continue the incision. The absence of visual clues creates a challenge for surgeons.

Elizabeth Davis, M.D., F.A.C.S., partner at Minnesota Eye Consultants, explains the crux of the issue. "With the Hansatome, you know the microkeratome is engaged with the suction ring because you can visually see the pin on the gear track. With this [the XP], it's more of a vertical pin inserting into an opening so you don't have any tactile feedback and there's less visual feedback," states Dr. Davis. "So, the only way you know the microkeratome is engaged is if you are able to proceed forward by stepping on the foot pedal. If it is not properly engaged, a stop is encountered."

Overcoming A Challenge

It's important to achieve adequate suction before proceeding with forward movement of the XP.

Dr. Davis reports on some methods to confirm adequate suction.

► Take tonometry measurements of intraocular pressure once the suction ring has been applied.

► Have the technician communicate that the vacuum shows that there is adequate suction on the ring.

► Look for pupil dilation.

► Ask the patient if his vision is dimming or blacking out when the IOP is raised. Differentiate conjunctival pseudosuction from true scleral suction.

Confirming Research

Standard deviation studies have been ongoing and results are due out in 2005. If studies confirm the variation is down to 10 microns, the XP will be one of the more consistent microkeratomes on the market.

For more information on the XP, contact Bausch & Lomb by phone at (800) 338-2020.