Ever since I. Howard Fine, M.D., introduced the clear corneal procedure at the American Society of Cataract and Refractive Surgery in 1992, surgeons have been looking for ways to use it in their surgical routines -- and to improve the technique.

• Dr. Fine offers advice for those doctors who are using this technique for the first time.
• Donald N. Serafano, M.D., discusses his latest innovation: using only a steel blade -- and a single incision.
• Howard Barnebey, M.D., writes about how he's bucking the trend toward ever-shrinking incision sizes, creating a stable, self-sealing wound as large as 3.6 mm.

Getting Started with Clear Cornea

by I. Howard Fine, M.D., P.C.

Eugene, Ore.

Clear corneal incisions offer numerous benefits for your patients and your practice:

• This is less invasive surgery. (The lack of subconjunctival bleeding is a major plus for the patient, although it has little to do with the ultimate visual outcome.)
• Temporal clear corneal incisions less than 3 mm long cause no surgically-induced astigmatism. They result in a stable refractive status within a week to 10 days.
• These incisions can be used in the presence of blood thinners and aspirin, which many senior citizens take for arthritis, as well as in the presence of bleeding dyscrasias.
• Postoperative restrictions aren't necessary. Except for swimming or contact sports, patients can return to work and other routine activities on the day of surgery.

If you're interested in adopting this technique, there are several things you can do to make the change go smoothly:

• Before you start, explain to the operating room personnel what you'll be doing and what you're trying to achieve, so they won't balk at changes in their routine.
• Move to the side of the bed. This may take some getting used to, so I recommend spending several weeks making temporal scleral tunnel incisions from this position. You may also need to change the position of your legs.
• If the mattress is thick, the microscope may be positioned too high for you to be comfortable. You may have to adjust the stools as well as the equipment.
• I usually have my assistant sit at the head of the table, with the microscope across from where I'm sitting.
• A tip from Bruce Wallace: Tilt the patient's head toward you and tilt the microscope toward the patient so that the visual axis of the patient and the axis of the microscope are congruent. This brings the oculars down and allows for a more comfortable position at the side of the bed.
• An angled speculum is a great advantage because it doesn't interfere with access to the eye.

Here are a few suggestions for clear corneal incision technique:

• Be sure to use topical anesthesia (or topical with intracameral), not injection anesthesia.
• I strongly prefer single-plane incisions because they seal and heal the best. However, if you're just beginning to make clear corneal incisions, a small groove at the edge of the clear cornea just central to the vascular arcade will facilitate the transition. The groove makes the incision easier to suture appropriately (if suturing becomes necessary).

Once you've mastered the learning curve you can stop using the groove. Although it's potentially helpful, the groove is a nidus for mucous and possible contaminants, and it leads to foreign body sensation.

• These sutures don't have to be pulled tightly. Their purpose isn't end-to-end approximation, but to tack the roof of the tunnel down to the floor of the tunnel.
• Too short an incision can lead to leakage and iris prolapse. Too long an incision will create corneal striae, making it more difficult to visualize intraocular structures.
• I prefer to test the incision with fluorescein dye to make sure it's well sealed. In almost every case, I do a quick and mild stromal hydration to facilitate that sealing.

Your equipment can significantly affect the quality of your outcomes.

• Blade.
I prefer the Rhine 3-D diamond blade. It's differentially beveled on the top and the bottom in such a way that you only need to touch the eye at the spot you want to enter and advance the blade in the plane of the cornea. The differential bevels make it self-directing.
The blade enters Descemet's membrane exactly 2 mm central to the external incision; it creates a straight line external and internal incision. (These blades will soon be available in metal.)
If you're not using a self-directed blade, make the incision in exactly the same way, by entering at the anterior edge of the vascular arcade and staying in the plane of the cornea. Once the blade is 2 mm in, you'll have to use a bevel-down technique to enter Descemet's membrane.
• Fixation device.
I prefer the Fine/Thornton ring, which I designed based on Spencer Thornton's fixation ring. It facilitates making both the side port and the cataract incisions.

Clear cornea instrumentation and technique will undoubtedly continue to improve. In the meantime, I hope these strategies will help you get off to a good start.

Using a Steel Blade -- and a Single Incision

By Donald N. Serafano, M.D.

Los Alamitos, Calif.

For many years, diamond blades and multiple incisions have been preferred for phaco and IOL insertion. When I first began using clear cornea incisions, I used a 2.8-mm diamond keratome for my phaco incision and a 3.5-mm short cut stainless steel blade for IOL insertion.

In 1998, I began using the 2.75-mm stainless steel Clearcut keratome (by Alcon) to make the incision for phacoemulsification, but I continued using a 3.5-mm stainless steel Shortcut blade to make the incision for IOL implantation. Then, in 1999,
3.4-mm Clearcut stainless steel blades and high infusion phaco tip sleeves and IOL injectors became available. These enabled me to perform phaco and IOL insertion using one 3.4-mm incision.

I switched from diamond to stainless steel blades for two reasons. First, stainless steel blades have improved to the point that diamond blades aren't necessary. Second, I disliked having to buy and repair diamond blades.

Clearcut stainless steel keratome blades now come in several sizes:

• 2.75 mm, designed for the phaco microtip (0.9 mm) and sleeve
• 3.2 mm, designed for the phaco standard tip (1.1 mm) and sleeve

• 3.4 mm, designed for either the phaco microtip or the phaco standard tip and a special silicone high infusion tip sleeve.

The new silicone high infusion sleeve has several advantages:

• It fits over the phaco microtip, phaco standard tip and the irrigation/aspiration (I/A) system of choice. (I'm currently using the steerable I/A system of the Legacy 20,000. I've also used the high infusion sleeve over a metal-sleeved I/A system.)
• It fills a 3.4-mm phaco incision without excess leakage.
• It has a tapered nose cone area so that the sleeve fits closely to the phaco tip. This prevents irrigation from exiting between the end of the sleeve and the tip.
• The close fit and taper allow fluidics to bring the nucleus to the tip and prevent them from pushing the nucleus away from the phaco tip.
• The close fit and taper allow you to enter into the incision without damaging Descemet's membrane.
• The larger irrigation ports allow more inflow to cool the tip and keep the anterior chamber stable.

By choosing an IOL whose injector system requires the size of incision you've already made, you can avoid the need for a second incision.

I currently use the Monarch Delivery System for insertion of the MA30BA AcrySof IOL, which can be inserted through a 3.4-mm incision. As a result, when I make the phaco incision with a 3.4-mm keratome blade, it doesn't have to be enlarged for the IOL injector. This allows me to perform the entire surgery through a single incision.

This system results in better efficiency, less cost, less tissue handling, excellent results and happier patients.

• I no longer need to enlarge the phaco incision to insert the IOL injector system.
• I only need to use one blade.
• There's no risk of traumatizing the phaco incision while enlarging it.
• I have consistent and predictable incision size and sutureless closure.
• My patients like the reduced surgery time and rapid recovery to full visual acuity potential

Are Smaller Wound Sizes Always Better?

By Howard Barnebey, M.D.

Seattle, Washington

Three years ago, I was performing cataract surgery by incising the conjunctiva and creating a temporal scleral tunnel. However, I noticed that pre-existing succulent filtering blebs decreased in size -- and on occasion failed -- following the surgery.

This prompted me to look for other approaches. Because of my experience, my major concern was bleb preservation, along with wound stability and leakage. Clear cornea was an obvious alternative.

At the outset, I intentionally tried to create a clear corneal incision that was as small as possible. I thought this would minimize any wound leakage and insure a stable wound. However, as I grew more comfortable with clear corneal incisions, I was surprised to find that complications with wound instability decreased dramatically when I enlarged the incision from 3.2 mm to 3.6 mm. The larger incision remained stable and astigmatically neutral, and it leaked less.

It turned out that intraocular lens implantation through a very tight incision (3.2 mm) damaged the corneal tissue. In fact, on one occasion, a small fragment of cornea tore off in the teeth of my forceps, which I was using for counter-traction, as I inserted a foldable implant. (Fortunately, the fragment was retrieved and repositioned with a 10-0 nylon compression suture, and no problems developed. Nonetheless, I didn't want to repeat the exercise.)

Wound architecture isn't solely a function of incisional chord length. As demonstrated by Paul Ernst, M.D., and Paul Langerman, M.D., the true barrier to leakage is located at the internal opening, Descemet's membrane. When using a 2- to 2.5-mm tunnel, a 3.6-mm incision is quite stable and has an internal seal at Descemet's membrane.

I also observed that after one or two attempts to glide the implant through the narrow passage, a small corneal incision needed to be enlarged anyway. The additional tissue manipulation required hydrodissection of the wound and occasionally a suture at the end of the case. A slightly larger incision minimized or eliminated these steps.

I did note another possible explanation for wound instability in incisions that need to be enlarged. As you enlarge, it's natural to tilt the blade in a slightly different plane than the original incision. This alters the three dimensional geometry of the initial incision.

I've found the following tips to be helpful for minimizing complications:

• Groove first: I recommend one-half corneal thickness (about 0.3 mm), starting just inside the peripheral corneal vascular arcade.
• Place viscoelastic in the anterior chamber to stabilize it.
• Introduce the tip of the blade with the tip up (toward the dome of the cornea) and the heel down. (I use a 3.2-mm Alcon keratome.)
• Fixate the globe. (I use a Fine/Thornton fixation ring.)
• Don't introduce the full extent of the blade into the anterior chamber until you're ready to insert the IOL. Limit the internal opening to 2.9 to 3.0 mm. This is easily done by stopping the blade when the widest portion of the blade is just inside the epithelial side of the incision.
• Be aware of the internal and external boundaries of the incision.
• After completing the phaco and I/A, fill the anterior chamber with viscoelastic and purposefully inject the viscoelastic material through the incision. This allows you to insert your keratome through the original incision easily, without creating a second independent tract.
• Enlarge the incision to 3.5 mm, being careful to keep the blade in the same plane (no rotating or trotting). This is especially important if you're using a keratome smaller than 3.5 mm, where horizontal to-and-fro movement is required to enlarge the incision.
• As you implant the IOL, appreciate the difference between snug (good) and tight (not good).
• Don't be afraid to enlarge the wound!
• Be familiar with the subtleties of blade design. Is the blade ground on both anterior and posterior surfaces or just one surface? How do these characteristics influence the tract created by the blade when you use it? For example, a blade that's ground on both sides, with the anterior cutting edge ground less steep than the posterior surface, tends to track anteriorally.
• After implanting the lens and removing the viscoelastic material, reform the anterior chamber through a separate paracentesis incision and check for leaks. If you have any doubts, hydrate the sides of the wound by injecting balanced salt solution (BSS) into the corneal stroma with a 30-gauge cannulae. Allow the corneal stroma to become opalescent in appearance.

My experience has convinced me that a shorter wound doesn't always produce a better outcome. If you follow the suggestions above, you should have good outcomes, minimal complications and enhanced wound stability -- even when the wound is as large as 3.6 mm.