feature
Why Bimanual Phacoemulsification?
The advantages of transitioning from coaxial to bimanual phaco.
BY FARRELL "TOBY" TYSON, M.D.

Despite enhancements in phacoemulsification technologies and awareness about safer techniques, there remains a debate about the benefits and drawbacks of implementing the bimanual technique for phacoemulsification.

When surgeons first started performing phacoemulsification, the ophthalmology community was not interested in using a small wound because you would have to enlarge it to get the rigid PMMA lens through. However, current enhancements of lens design provide smaller lenses that can be rolled. Today, we are perfecting bimanual instrumentation, which is going to force manufacturers to come up with lenses that can go through smaller incisions. This is the future of cataract surgery.

Recent Advances in Technology and Technique

The advancement in phaco in regard to micropulsed technology has decreased the amount of energy that is needed to complete each procedure. This enhancement, in conjunction with the surgeon's ability to apply WhiteStar ICE phaco pulse modification (Advanced Medical Optics, AMO, Santa Ana, Calif.), increases the efficiency of ultrasonic energy and improves followability and cutting efficiency.

As technology advances and incision size decreases, surgeons may find it necessary to consider the transition from coaxial to bimanual. Smaller incision size means decreased likelihood of induced astigmatism and faster recovery. Also, the clear corneal incision created by bimanual phaco creates a more secure seal because there is less movement at the incision site.

I have been performing bimanual phacoemulsification for the past 2 years, using AMO's Sovereign system with WhiteStar technology and the MST duet handpieces (MicroSurgical Technologies, Redmond, Wash.). Currently, about 20%-30% of my cataract cases are performed with bimanual phaco.

In this article, I will detail my experience with transitioning to this technique, as well as identify the best manner in which to facilitate the transition through patient selection and surgical tips.

Patient Selection for Bimanual Phaco

Patient selection is a key factor for completing a successful bimanual case. I am currently selecting my patients based on the type of cataract they have. If a patient has a fairly dense to extremely dense cataract, I will perform bimanual because I know it is going to use less energy to get the job done.

Bimanual phaco is a useful tool when it comes to treating patients who are considered high risk. High-risk patients include those with weak zonules, or those who have small pupils. The separation of irrigation and aspiration (I&A) proves to be a useful tool in these cases because the division of vacuum and flow minimizes complications.

There are other advantages to having a separation of I&A when it comes to complicated cases. It is important to consider the use of bimanual phaco during floppy iris cases. A surgeon can use irrigation to push the iris away from the phaco tip, which often occurs during these cases.

I recently completed a 125-eye study comparing bimanual vs. coaxial phaco. When removing 2+ nuclear sclerotic cataracts, I found that I achieved approximately a 54% reduction in energy used with bimanual WhiteStar vs. coaxial WhiteStar, so I knew that I was going to get clearer corneas.

When I performed bimanual on patients with 3+ nuclei, which I consider to be a brunescent rock, I found there was a 35% reduction in phaco time. Therefore, whenever I have a brunescent cataract or an extremely dense one, I am going to use the bimanual technique. Knowing I am going to be in the eye longer and using more energy, I am going to want to use the least amount of energy possible to have the clearest corneas.

In minimal cataract cases the nuclei are so soft surgeons are mainly using I&A and not phaco, so the difference between coaxial and bimanual are minimal. Therefore, I use coaxial phaco in these cases since I can perform them more quickly.

Advantages of Transitioning to Bimanual Phaco

The most common hurdle that phaco surgeons will encounter when transitioning to bimanual phaco is learning how to use their second hand more effectively. The instrumentation may feel more bulky in the eye and the flows will tend to move differently.

With bimanual phaco, it is possible to use your irrigation as a tool so that you can use the flow to push pieces of the cataract around. At the same time, the instrumentation is larger, and therefore, surgeons may find it difficult to adapt to the change in available space until they get comfortable with the technique. I recommend starting out with one of the smaller sized I&A choppers available.

An advantage that must be considered while using bimanual is that it allows for continuous irrigation while the surgeon exchanges from the phaco needle to the I&A system. This leads to increased surgeon control and efficiency of the procedure. Some surgeons do not have the ambidextrousness that makes this technique easier to perform. Over time it will become clear that large movements with the I&A hand are not necessary and that small movements can be quite effective in manipulation of nuclear pieces.

The movement of fluidics is an extremely important aspect of phacoemulsification. With bimanual, the fluidics flow allows material to move throughout the eye without disturbing any additional intraocular features. Another aspect of bimanual that surgeons will find useful is the separation of I&A, which aids in polishing the posterior capsule along with the ability to change hands with the instrumentation to better engage subincisional cortex.

The major reason for surgeons to transition to bimanual is that they will experience better fluidics in the eye, allowing them to use the infusion as a tool instead of the repulsion of nuclear particles as seen in coaxial phaco. Bimanual phaco means smaller incisions, which, with the proper instrumentation, seals very well. With a standard wound, very little astigmatism is induced, but with two smaller wounds you will have even less and with refractive IOLs, monitoring induced astigmatism is key.

Using the WhiteStar System

The WhiteStar system is the only phacoemulsification system to have true cold phaco technology. Therefore, it is the only system that I feel comfortable using in a bimanual scenario. With this setup, I have no problems with thermal wound damage even with the high-molecular weight
Healon 5 (AMO). Other systems are looking to leaky wounds to provide cooling, but with the WhiteStar bimanual system, I can operate with tight wounds for better fluidics.

The smaller incision size related to bimanual phaco also improves chamber stability because the viscoelastic that is needed to perform the procedure is less likely to come out through a smaller incision size. The incision size of bimanual phaco reduces post-occlusion surge as well as the amount of balanced salt solution needed, which also protects against endothelial cell loss.

Tips for Transitioning to the Bimanual Technique

When transitioning from coaxial to bimanual, first start by trying to make your capsulorrhexis through a paracentesis port with one of the micro instruments. This is an important step to adjust to because the feeling is different. Also, surgeons will want to use a medium molecular weight viscoelastic because of the way the pieces move throughout the eye. Healon GV (AMO) works very well and I have also successfully used Healon 5. However, I find that it does slow the movement of the pieces, so I prefer Healon GV.

Phacoemulsification system selection is also an important consideration for any surgeon who is looking to transition to this technique. Considerations include how much thermal damage will be caused by the machine; it is important to select a machine that will cause the least amount of potential wound burn.

Surgeons should consider making the shift to bimanual phaco after using the capsulorrhexis forceps and getting comfortable with it. I find this technique to work extremely well through a two-incision set up in which I do not need a third port. With the MST set, I get very good chamber maintenance and good ceiling. The MST set also ensures minimal side movement of the needle and allows for the phaco needle to be maintained inside the pupil. I find it helpful to use an Accutome diamond blade (Malvern, Pa.) that creates a 1.5 mm internal wound with an expanded external wound.

This type of wound for the irrigation port and phaco port allows for increased mobility and decreases "oar locking." The phaco incision can later be enlarged to about
2.5 mm by advancing the diamond blade to its widest point. This allows for injection of the lens through a 2.5-mm incision. I then continue with bimanual I&A and get good wound sealage so I do not need a third incision.

Tradeoffs When Transitioning

When dealing with bimanual phaco, more instrumentation is required, which can get in the way of the quadrants moving. I find it useful to make a larger capsulorrhexis since you are using capsulorrhexis forceps, and there is a natural tendency in bimanual cases for the rhexis to run out to the periphery. Therefore, you have to try harder to get a standard size capsulorrhexis.

When you are performing coaxial phacoemulsification, you can hydrodissect minimally and have plenty of mobility to go back and change it later. With bimanual, surgeons will want to get the lens spinning in the bag prior to entering the bimanual instrumentation. If hydrodissection is not adequately performed, it is more difficult to manipulate the adherent quadrants with the larger bimanual instrumentation.

Surgeons who are making the transition to bimanual will initially be slower, and I find that it takes around 4 to 5 weeks in the operating room to regain your coaxial speed. In addition to the surgeon having to acclimate himself, the scrub technician also needs to become familiar with the new instrumentation. I find it best to train one scrub in one OR at a time. Repetition breeds familiarity, increasing case speed.

From a cost perspective, after a practice has the instrumentation, it is a fixed cost. There are no additional costs affiliated with bimanual.

In my opinion, the ability to perform bimanual will set you apart from your colleagues. In my practice, we have successfully marketed bimanual phaco and cold phaco technology, which in turn has brought more patients to the practice because we are doing the "latest and the greatest."

Farrell Tyson, M.D., practices refractive cataract and glaucoma surgery in Cape Coral, Fla. He obtained his biomedical engineering degree from Johns Hopkins University. He completed his ophthalmology residency at the Storm Eye Institute in Charleston, S.C. Dr. Tyson is currently involved in several FDA trials and is a national and international speaker on multifocal lenses, endoscopic cyclophotocoagulation and biometry.