Ensuring the Peak Performance of Your Microkeratome
Experienced surgeons and staff members provide checklists of key points.

Proper assembly, cleaning and maintenance of your microkeratome are essential for ensuring patient safety and obtaining ideal refractive surgery results. To help you double-check and improve your procedures, Ophthalmology Management asked several leading refractive surgeons and their staff members to highlight the most important aspects of caring for some of the top-selling brands.

April White, C.O.T., refractive surgery first assistant and clinical team coordinator with Roger Steinert, M.D., pointed out that none of the steps in any manufacturer's instruction manual should be skipped or viewed as inconsequential. She also said that practices should consider the manufacturer-provided wet lab an essential part of staff training. Unfortunately, in some practices, other technicians always train new staff members, increasing the chances that important information will be forgotten. The best way for a practice to be clear about the important nuances of using each microkeratome is to become familiar with each instruction manual and to train with each manufacturer's representative, she said.

Also, it is Ophthalmic Consultants of Boston's policy that the number of people who handle the microkeratomes be kept to an absolute minimum. To achieve maximum keratome performance, the practice has designated three technicians who devote themselves to making sure the instruments are well taken care of and that they can troubleshoot any potential problems. White said the practice's incidence of flap-related problems declined when they reduced the number of people handling the microkeratomes.

She offers her advice, beginning below, on the Hansatome, Moria C-B and Moria M2. Then, others highlight key points about the instruments they work with.

BAUSCH & LOMB HANSATOME

The Hansatome is often referred to as the workhorse of microkeratomes. It creates a hinge in the superior position, which many physicians prefer. It pivots on a pin and moves across a gear track. This microkeratome is widely used and dependable, but strict adherence to manufacturer's guidelines regarding care and maintenance is crucial. Remember, when handling any microkeratome, it's important to use sterile, powder-free gloves.

At the beginning of each surgery day:

Check the vacuum pump on the control unit to make sure the patient vacuum is 4 mm Hg below the atmosphere. Otherwise, proper intraocular pressure may not be obtained and maintained.

Check the motor to be sure the milliamps are running under 40. When they're not, we dip the pin of the motor in 99% anhydrous alcohol, run the motor in forward and reverse for approximately 30 seconds, and then depress the pin with a lint-free sponge (we use Merocel) to express any alcohol that may be trapped inside. This will lower the milliamp draw. We use the 99% anhydrous alcohol because it contains less water than 70% alcohol. Water with sodium can corrode and damage the internal gears. Therefore, we never use balanced salt solution (BSS) as a lubricant or allow it to have any contact with the motor. It's also important to use only lint-free disposables near the microkeratome so lint doesn't become trapped inside the head or the motor pin and potentially cause a jam.

During assembly of the Hansatome:

Our first step is to place  a drop of Proparacaine in the blade channel to help the blade glide better during oscillation. (Proparacaine contains glycerin, which has a lubricating quality.)

Next, we insert  the blade into the blade channel. We test blade movement by sliding it back and forth inside the channel with the blade insertion pin still attached to the blade. If the blade isn't moving freely, we carefully remove the blade without touching its cutting edge. Then, we rub a lint-free surgical spear moistened with Proparacaine inside the blade channel to remove any debris that may be trapped inside, place another Proparacaine drop in the channel, and reinsert the blade. If movement still seems encumbered, we remove the blade, and clean and resterilize the head.

Once resistance isn't a problem, we attach the eye adapter, which designates the operative eye. For bilateral procedures, we always begin with the left eye.

After this step, you can attach the motor. As you screw the motor pin into the head, make sure the blade is traveling back and forth in the channel. This means the pin is properly engaged in the blade, and the blade will oscillate properly.

The microkeratome head should be cleaned and  sterilized, of course. We fill three small cups with hot, sterile water. One of the cups contains a medical-grade enzymatic cleaner diluted to manufacturer's specifications. (Bausch & Lomb had previously recommended Palmolive as the cleaning agent. But, effective Jan. 1, 2001, in response to comments from laser vision correction centers and surgeons using the microkeratomes, the company changed its recommended cleaning regimen. It now recommends cleaning with a pH-balanced enzymatic cleaner, such as Klenzyme, Enzol or Cidezyme. Other recommendations have changed as well. All are available through Bausch & Lomb Surgical.)

We scrub the head with a denture brush, paying careful attention to the blade channel in the cup with the enzymatic cleaner. We then rinse in the other two cups to remove any remaining cleaner. After rinsing, we dry the head and force out remaining water with microfiltered, compressed air. We sterilize in our STATIM 5000 sterilizer for the next case.

At the end of each surgery day:

We clean the head the same way we did between cases. We pay special attention to drying to prevent metal oxidation. We clean the motor pin in 99% anhydrous alcohol again, testing forward and reverse motion for 30 seconds. We depress the pin on a surgical sponge to express any fluid trapped inside. Finally, we store the motor with the pin down so that any liquid still inside the body will drain down and out.

-- April White, C.O.T., Ophthalmic Consultants of Boston

MORIA C-B

The Evolution II control unit operates both the C-B manual and automated microkeratomes. There are no milliamp readings to monitor resistance with the C-B control unit. So, your first step is to switch the control unit to manual or automated mode. The keratome heads are interchangeable, and we follow the same steps outlined for the Hansatome for blade insertion.

• If you're using the manual C-B: Once the blade is inserted and the head attached to the motor, turn on the vacuum and depress the forward pedal to check for proper blade oscillation. Monitor the pounds per square inch (PSI) reading to be sure it's maintained at an acceptable level.
  The blade oscillation speed, which is controlled by nitrogen, is 15,000 RPM, higher than the 12,000 RPM of the automated C-B. The PSI should be constantly watched and maintained by increasing or decreasing the flow of nitrogen to the control unit. We always compare the PSI reading with vacuum off with the PSI reading after vacuum is turned on. If the PSI drops 3 to 4 points below what the PSI reading was without vacuum on, chances are you have a gas leak. Rectify this immediately because oscillation speed will be compromised. Because the manual C-B motor contains no internal gears, you can sterilize it. But, again, be sure to dry it thoroughly to avoid metal oxidation.
• If you're using the automated C-B: After the blade is inserted and attached to the motor, ensure proper blade oscillation by turning on the vacuum and pressing the forward pedal. Once oscillation is confirmed, you can place the assembled keratome on the suction ring.

Care of the motor is the same as for the Hansatome.

Both the manual and automated  heads should also be cared for the same way as the Hansatome, with one exception: You should turn the wheel inside the C-B with a small denture brush. If it doesn't turn freely, send the instrument back to the manufacturer to be repaired.

-- April White, C.O.T., Ophthalmic Consultants of Boston

MORIA M2

Our facility is among the first to acquire this microkeratome. It is also controlled by the Evolution II control unit.

The motor translates much faster than the C-B automated, leading to shorter suction time. For surgeons who are uncomfortable using the manual C-B, but prefer some of its features, the M2 has a blade oscillation speed of 15,000 RPM, which is comparable to the C-B manual.

Care and sterilization of the M2 motor and head are the same as with the Hansatome and C-B automated. Assembly of the M2 is the same as the C-B automated.

-- April White, C.O.T., Ophthalmic Consultants of Boston

BAUSCH & LOMB ACS

Prior to assembling the ACS, we check the blades for defects using the blade holder and oculars from our laser on 4X magnification.

We also make sure the unit is bone-dry to allow for free movement of the blade block and gears.

For assembly:

Using the depth plate tool, insert the desired plate into the head and hand tighten. Be sure to listen for a "snap" as you insert the plate. If you don't hear it, the plate may not be securely flush against the microkeratome head, opening up the possibility of an anterior chamber perforation.

Don't forget the stopper ring. This could result in a free cap.

For cleaning the ACS:

We use three plastic emesis basins so that themetal-to-metal scratching with stain-less-steel basins isn't a problem. Each contains sterile or distilled water. One basin contains an enzymatic cleaner diluted to manufacturer's specifications. (Bausch & Lomb had previouslyrecommended Palmolive as the cleaning agent. But, effective Jan. 1, 2001, in response to comments from laser vision correction centers and surgeons using the microkeratomes, the company changed its recommended cleaning regimen. It now recommends cleaning with a pH-balanced enzymatic cleaner, such as Klenzyme, Enzol or Cidezyme. Other recommendations have changed as well. All are available through Bausch & Lomb Surgical.)

We never use tap water; it contains minerals that could  form deposits or rust.

We use one toothbrush in each of the three basins. This ensures that all particles and cleaner are removed. We clean toothbrushes with sterile water and nonlinting tissues and replace them every 6 weeks. This helps prevent bacteria build-up that could lead to Sands of Sahara.

We wear powder-free gloves to prevent any particles or skin cells from getting into the gears.

Prior to each case:

Check for proper blade oscillation. If a blade isn't oscillating, it's likely that either the locking nut was placed on backward or the blade block was placed facing the wrong direction. Once the case is under way, Dr. Robin recommends supporting the ACS with one or two fingers underneath the stem (where the motor cord connects with the motor) to help prevent torque.

For maintaining the ACS, we recommend:

Checking periodically for any burrs or scratches on the unit head (including the footplates), depth plate, and tracks of the suction ring. Scratches and burrs can lead to a less than satisfactory result.

Storing bone-dry; no pieces or parts should be damp or partially dry. Microfiltered compressed air is the most effective way to keep the pieces dry.

Storing the motor with the cap on and the tip down. This helps to keep the gears within the motor lubricated.

-- Jay Haughton, R.N., surgical technician with Jeffrey Robin, M.D., in Tampa, Fla.

ALCON SUMMIT AUTONOMOUS SKBM

We insert the blade back-end first, securing an index finger on the left side of the head so the blade doesn't fall through the other side. After blade insertion, we use one drop of lubricant eye drop solution to lubricate the blade and reduce friction.

When attaching the head onto the handpiece, we make sure that the eccentric pin is placed at the 6 or 12 position and the blade is centered inside of the head.

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	If you're in the market for a new microkeratome, don't miss the June Ophthalmology Management. The issue will contain an at-a-glance review of available products and their features. Use the guide to see which instruments offer the features that are important to you and your outcomes, from flap options and ease of assembly to visibility and factors that affect the smoothness of the cut.

If the head doesn't snap into place, check both pin and blade placement. Rotate the head left to right to ensure it's in the locked position.

As you attach the stainless metal drive band into the rails underneath the handpiece, use the thumbknob. Gently arch the band toward the hole at the end of the slit over the guide pin, pushing the band into place until it clicks into position.

Before each case we test the unit. We pinch the tubing to simulate suction, engage the head into the ring and depress the cut pedal. While the apparatus is in motion, we ensure proper band-to-cone engagement, pulling it backward to ensure it's latched.

We use an enzymatic cleaning solution mixed to the manufacturer's recommended concentration, and flush with distilled water. Extra care is taken when cleaning the multiple suction ports inside the rings with a toothbrush.

Once a week we clean with SurgiStain cleaning solution to remove any rust or corrosion stains. This solution also helps to free any stiffness in the ring tracks.

We don't use alcohol to clean the rings, head, tonometer, ring handle, corneal marker or drive band. Alcohol breaks down the adhesive in the applanation window. Components that are nonautoclavable, such as the motor blocks and cables, may be wiped gently with a lint-free alcohol swab.

After sterilization and before each case, ensure that all components are dry (we use compressed air).

Take special care to inspect the applanation window, as any moisture residue may cause a false meniscus reading resulting in a free cap.

Check the metal drive band for any "play or slip" when it's engaged on the ring. Although the manufacturer can't predict the lifetime of the band, we replace ours every 50-75 cases.

Take precautions to ensure that the applanation window on the head does not get scratched (we store both head and handpiece in a small plastic bag).

Ensure that all components are stored in a dry, dust-free environment. Properly wrap and store the foot pedal and handpiece cords to prohibit crimping of the connectors.

-- Jay Haughton, R.N., surgical technician with Jeffrey Robin, M.D., in Tampa, Fla.

NIDEK MK-2000 KERATOME SYSTEM

Only two of us handle the MK-2000 -- my surgical assistant and myself. Assigning care and maintenance to one person, someone attentive to detail, ensures protocol is followed.

To ensure we were adept with the MK-2000, my surgical assistant and I repeatedly assembled and disassembled the three pieces. Ill-assembled pieces or skipped steps can lead to harming the patient or ruining the instrument.

On days when we perform procedures, we use two sets of blade holders (130 and 160 um) and suction rings (8.5 and 9.5 mm). While one set is in use, the other set is cleaned and steam-sterilized.

Before re-assembly with a freshly sterilized set, we wipe the motor with 70 percent ethyl alcohol. Both sets and the suction tubing are cleaned and gas-sterilized nightly.

Each time I'm handed the keratome, I examine the three-piece assembly under a microscope, watching for abrasions or debris that could prevent the blade from advancing smoothly or cause harm to the cornea. This takes less than a minute.

Before each case, advance and back up the blade to ensure proper movement. Even with training and years of practice, it's important to check running parts right before surgery.

Listen to the sound of the assembly. The MK-2000 runs smoothly and quietly. A head that isn't assembled correctly will have an unusual pitch.

We've found that placing a thin film of lubricating artificial tear onto the cornea prior to microkeratome placement improves flap quality, decreases the frequency of epithelial defects and helps the blade advance smoothly.

-- Mark Morin, M.D., Vision Care of Maine

ALLERGAN AMADEUS

Connect the power, pedal, and handpiece cables to the control unit before switching it on.

Verify that the size of the suction ring corresponds with the setting on the control unit.

Connect the vacuum tubing before attaching the suction unit to the handpiece. Make sure the vacuum tubing is on top when attaching the reservoir to the control unit.

Apply a lubricant (not saline solution) to the blade holder railings and the suction unit tracks before sliding them together and pushing the tappet in. Don't pull the tappet out unless you have completed the keratectomy or aborted.

Clean the blade holder and suction unit with an FDA-approved cleaner (never saline solution) before autoclave sterilizing them. Pay special attention to the applanation plate and slit where the flap passes through as well as the blade holder railings and suction unit tracks.

Wipe down the other mechanical and electrical components, which can't be autoclave sterilized, with 77% to 80% alcohol.

Discard the blade and vacuum tubing.

Replace the battery at the end of its lifetime or if the control unit reports a weak battery and re-initializing the battery does not correct the report.

-- Lee. T. Nordan, M.D., Nordan Laser Eye Institute, Carlsbad and La Jolla, Calif.