Surgeon: new maneuver aids in phaco

The maneuver, intralenticular posterior viscodissection, makes it easier to mobilize dissected quadrants during phaco.

Issue: September 15, 2002

ByStephen T. Conway, MD

I have recently developed a new surgical maneuver, which as far as I know has not been previously described. The idea occurred to me during a case in which, after performing a standard divide-and-conquer technique, I had difficulty mobilizing one of the four quadrants I had just created. This is a common problem secondary to the natural elasticity of the lens capsule, which tends to push the pieces back together again during divide-and-conquer especially, but also during phaco chop.

In fact, there is a fundamental self-contradiction in phaco. While the surgeon is trying to pull the nuclear pieces away from the posterior capsule for safe emulsification, the forces of the fluid stream emanating from the phaco tip are pushing the nucleus posteriorly against the posterior capsule.

The problem

The angled tip of the viscoelastic cannula is placed between the two nuclear pieces created by chopping.

Viscoelastic is slowly injected between the two pieces, atraumatically separating them.

The viscoelastic lifts and separates the two pieces, creating significant space for further maneuvers.

The pieces are easily separated from each other during the divide-and-conquer or chopping phase of the surgical procedure because the adjacent edges of the two pieces created during the cracking procedure are now being held apart from each other by the two instruments in the surgeon’s hands.

However, when the surgeon begins to perform emulsification of the fragments, it is difficult to find an edge that the phaco tip can latch onto to safely emulsify the first piece. If the nucleus is relatively soft, it is dangerous to just place the phaco tip on one of the pieces to attempt to elevate it from the posterior capsule and emulsify it at the same time. If the nucleus is soft, the phaco tip may go right through the soft nucleus and hit the posterior capsule.

If the nucleus is hard, it may be difficult to get a good purchase on the surface on one of the pieces and elevate it away from the posterior capsule. This is the same phenomenon as trying to remove one piece from a completed jigsaw puzzle on a flat surface. Once one piece is removed, the remaining pieces can be easily removed by pressing your finger against the edge of one of the pieces around the hole and then pushing it up. But it is very difficult to elevate one piece of a completed puzzle.

A solution

My solution to these problems is as follows: after creating the nuclear pieces I examine the edges of the fragments carefully. Although the edges of the fragments are in close contact with each other, there are usually a few spots where the edges of the pieces are not perfectly aligned and there is a little notch or defect between the two borders.

Once I have identified this little spot between the edges of two pieces, I place the angled tip of the viscoelastic syringe into this little defect with the ostium of the cannula facing posteriorly toward the posterior capsule. I then slowly inject viscoelastic.

As the viscoelastic is injected it atraumatically separates the adjacent lens fragments from each other, and because it is spreading posteriorly it also lifts the nuclear fragments away from the posterior capsule and in fact creates a significant space between the posterior capsule and the posterior surface of lens fragments. This is obviously a tremendous advantage for the surgeon.

At this point, to help further mobilize the pieces anteriorly for emulsification, I will use a blunt instrument like a blunt rounded-tip chopper or a Connor wand to push the lens fragments a little more anteriorly for a safe emulsification. In the past, before I developed this technique with the viscoelastic, I occasionally passed a Drysdale instrument between the posterior capsule and the posterior surface of the fragments of the nucleus in an attempt to mobilize the nuclear fragments anteriorly away from the posterior capsule for safer emulsification.

However, when using that technique I occasionally was unpleasantly surprised to find a tear in the posterior capsule as the emulsification of the nucleus progressed. I suspected that this tear was caused by the insertion of the Drysdale between the posterior capsule and the lens nucleus. Although the Drysdale is dull and flat, if the posterior capsule or zonules happen to be very fragile, it certainly is conceivable that even a small amount of pressure from a rigid instrument could cause a tear in the posterior capsule or the zonules.

I have been using this viscodissection technique for a year now and am very pleased with it. I have not yet identified any complications.

Theoretically, if the surgeon is overly enthusiastic in injecting viscoelastic between the posterior surface of the lens fragment and the capsule, it is conceivable that in filling the posterior capsule with as much viscoelastic as possible, a tear could be created from the pressure of the viscoelastic.

I have not yet seen that in my experience. It is fairly easy to create a tear in the posterior capsule even with a blunt instrument like a Drysdale if enough pressure is exerted on the posterior capsule, but in viscodissection it is very difficult to create high pressure at a small point using viscoelastic.

For Your Information:

Stephen T. Conway, MD, is a clinical assistant professor, ophthalmology-oculoplastic surgery, Brown University Medical School. He can be reached at 465 East Ave., Pawtucket, RI 02860; (401) 728-9350; fax: (401) 728-1320; e-mail: conway@webmd.com.