22 gauge bimanual phaco: the final frontier?

September 1, 2006

It ensures faster rehabilitation of patients operated on using 22 gauge compared with conventional 2.8 mm coaxial phaco, probably because of the reduction in postoperative trauma during emulsification of the crystalline lens in a closed system with narrow incisions

With this in mind, 22 gauge bimanual phacoemulsification has been developed, marking the most recent innovation in biaxial microincision phacoemulsification. As with any new technique, it requires a learning curve because the various, specific stages involve narrow-gauge instruments and incisions of less than one millimetre. Although the problem of implanting via infra-millimetric incision is not yet resolved and remains a research topic, this surgery could represent the future of phacoemulsification.

Quality precision is essential

The quality of microincisions is key to ensuring a trouble-free procedure using 22 gauge bimanual phacoemulsification. The width of these incisions must be perfectly suited to the 22 gauge instruments; they should not be too wide, to avoid leakage.

On the other hand, they should be wide enough to manoeuvre the instruments and prevent them from deforming the cornea, thus reducing the view of the surgical manipulations.

A step-by-step guide to performing 22 gauge bimanual phacoemulsification

• To begin

Two 0.8 to 1 mm incisions are made, with a 90° angle between them, which allows us to avoid induced astigmatism. Using a precalibrated knife, the incisions should preferably be trapezoid-shaped, which is a good compromise between water-tightness and instrument mobility.

• The capsulorhexis

Capsulorhexis may be performed using forceps or a needle. We prefer to use the 23 gauge distal DUET forceps, inspired by the forceps used in vitreoretinal surgery. These forceps have a short beak for better manoeuvrability and a smooth tip to prevent springback during insertion into the incision.

The use of a viscoelastic solution that is both dispersive and cohesive appears a satisfactory compromise to facilitate a circular, continuous incision in the anterior capsule of the crystalline lens.

This circular rhexis with forceps is obtained by tangential traction and centripetal movements by picking up the capsular flap at its hinge approximately every 60 degrees.

Using a needle, and holding the capsular flap well spread out over the anterior cortex of the crystalline lens, the rhexis can be moved using small tangential movements on the extremity of the cystotome.

The difficulties of 22 gauge microincision lie in the risk of making a rhexis that is too small or irregular on the far side of the incision. Lesion risk of this type of capsulorhexis may make it difficult to continue the intervention.

• Then comes hydrodissection

Hydrodissection does not require any specific equipment in 22 gauge bimanual phacoemulsification. However, the higher water-tightness of microincisions means that part of the viscoelastic needs to be removed using a Pearce cannula before beginning hydrodissection. This must be performed gently in order to avoid excess pressure in the chamber and posterior capsule rupture.