Challenging and complicated cataract surgery, such as in patients with zonular weakness or dehiscence, intraoperative floppy iris syndrome, an extremely shallow anterior chamber, or corneal endothelial dystrophy, requires a less-than-routine surgical approach. In these situations, intraoperative pressure variance, ocular turbulence, and leakage of irrigating solution through a sideport incision may negatively affect the outcome.
A high aspiration flow rate, often employed with traditional longitudinal phaco to reduce lens chatter, may attract the vitreous or a floppy iris into the phaco tip. Additionally, high flow and turbulence in the anterior chamber will evacuate viscoelastic, reducing the protection of the endothelium during surgery. The direct impact of mobile, chattering nuclear fragments will also cause substantial turbulence and result in endothelial cell loss.
A high vacuum level, also used to enhance efficiency with longitudinal ultrasound, may cause significant post-occlusion surge when an occlusion break occurs. The result is increased anterior chamber instability and fluctuation in intraocular pressure (IOP), which may destabilize and escalate the danger of a complicated case. If an eye has zonular weakness and chamber instability, zonular dehiscence may develop or intensify. Nonetheless, a certain amount of vacuum and flow is required to efficiently bring material to the phaco tip and remove dense nuclear material.
SUFFICIENT INFLOW
Incresing the bottle height induces larger pressure variances during surgery. After occlusion break, IOP can drop from a high to low level instantly. High bottle settings are normally used to guarantee a sufficient inflow.
Leakage through a sideport incision may induce iris prolapse in patients with intraoperative floppy iris syndrome or a very shallow anterior chamber in patients with narrow pupils. Creating a small sideport helps to minimize leak flow but will not totally eliminate it.
The Dual Coaxial Irrigation Kit (Alcon Laboratories, Inc., Fort Worth, Texas) was developed to eliminate leakage and significantly enhance irrigation. Therefore, the surgeon is able to work with the ideal fluidics characteristics for complicated cataract cases: very low bottle height that allows maintenance of sufficient irrigation flow and a completely closed anterior chamber, free from leakage, with significantly reduced turbulence. Followability is greatly improved because of the lack of leakage.
DUAL COAXIAL IRRIGATION KIT
This kit utilizes a split infusion line that provides two infusion delivery routes: one through the phaco handpiece and the other via an irrigation handpiece with an attached sleeved manipulator (Figure 1). This arrangement increases infusion capacity (Figure 2), aids in providing adequate infusion flow despite a low infusion bottle height, and results in a low IOP with adequate infusion capacity, due to multiple infusion sites. Both the infusion and phaco handpieces have silicone sleeves and are able to seal the incisions through which they are inserted.
The irrigating handpiece replaces the regular second instrument. A variety of specially threaded nucleus manipulators or choppers may be mounted onto the handpiece. I have tried three handpiece tips, the Bechert fork, Kellan nucleus manipulator, and Nagahara chopper (all manufactured by ASICO, Westmont, Illinois).
DUAL MICROCOAXIAL SURGERY SETTINGS
I use the following system and settings in complicated cases. I create two 2.2-mm incisions, approximately 90° apart, with a HP2 double-bevel knife (Alcon Laboratories, Inc.). I use the OZil handpiece with a 45° Kelman Mini-Flared tip and Ultrasleeve (all manufactured by Alcon Laboratories, Inc). Through the second incision, I use an Ultraflow (Alcon Laboratories, Inc.) handpiece with a threaded Bechert or Kellan nucleus manipulator tip, also with an Ultrasleeve.
The Dual Coaxial Irrigation Kit tubing connects the irrigation line of the OZil handpiece to the second irrigating handpiece. I use the new Intrepid FMS (Alcon Laboratories, Inc.) with lower compliance tubing.
During quadrant removal, my bottle height is 50 cm, the aspiration flow rate is 20 mL/min (fixed), vacuum is 300 mm Hg (fixed), and I use 75% linear continuous torsional ultrasound. For cortex removal, I replace the OZil handpiece with an Ultraflow I/A handpiece featuring a silicone aspiration tip. My bottle height is again 50 cm; however, the aspiration flow rate is 15 mL/min (linear) and the vacuum is 500 mm Hg (linear).
Anterior chamber stability with this system and settings is remarkable, and turbulence is minimal. The level of control is greatly enhanced with this OZil Intrepid system and the Dual Coaxial Irrigation Kit.
Khiun F. Tjia, MD, is an Anterior Segment Specialist at the Isala Clinics, Zwolle, Netherlands. Dr. Tjia is the Co-Chief Medical Editor of CRST Europe. He states that he is a research consultant to Alcon Laboratories, Inc., but that he does not have any financial interest in the products mentioned. Dr. Tjia may be reached at kftjia@planet.nl.
