Not all white cataracts are the same and in this category, among the most challenging is the intumescent white cataract. This is a type of cataract where the lens cortex has opacified and liquefied. As such, it increases the intra-lenticular pressure within the capsular bag which can cause complications such as the Argentinian flag sign where the capsule splits uncontrollably.
Many different approaches to the intumescent white cataract have been described in order to minimize the risk of an errant capsulorhexis. Needle decompression can be performed with aspiration to remove much of the liquefied lens material while lowering the intra-lenticular pressure. Using an automated device such as a femtosecond laser can help but is no guarantee of a perfect capsular opening. Newer automated devices can deliver electrical pulses of energy to quickly create the capsulotomy but require additional hardware. Another approach is to simply use the phaco probe.
The technique of phaco puncture uses the phaco tip along with a brief burst of ultrasound energy followed by gentle aspiration of the liquefied lens material. The phaco probe is placed tip-down towards the center of the anterior lens capsule (figure A). Next a brief burst of phaco energy is delivered which punctures the lens capsule, followed by gentle aspiration of the liquefied lens material. This quickly and effectively opens the anterior lens capsule and decompresses the capsular bag. Once this is completed the risk of an errant capsular tear is greatly decreased and now forceps can grab the edge of the capsule to begin a controlled tear (figure B).
Since the risk of Argentinian flag sign is low, we can take our time to use the forceps to complete a precise capsulorhexis (figure C). At the end of the surgery, the IOL is accurately positioned and secured by the capsulorhexis which has 360 degrees of optic overlap (figure D).
For this technique the settings of the phaco machine are critical to ensure success and minimize the risk of complications. With a very soft, intumescent cataract, excessive phaco energy or vacuum aspiration can cause the phaco tip to go through the entire lens and rupture the posterior capsule. To avoid this issue, we need to choose specific phaco parameters that are designed for phaco puncture.
The ultrasound energy should be delivered briefly and at a relatively low level which we can achieve by programming the appropriate phaco power modulations. We want a single burst mode with that burst lasting just 10 to 20 milliseconds, an energy level of about 20%. This is enough to puncture the lens capsule as long as the phaco tip is in good contact with the anterior surface.
For the vacuum and aspiration flow rate, we want low level parameters so that we are gentle with these delicate ocular structures. Using a flow rate of 20 cc/min and a vacuum level of 100 mmHg should be sufficient for our purposes. For placement of the phaco tip, when entering the eye the foot pedal should be on position 1 which is just irrigation. Then when the tip is placed bevel down and directly on the anterior lens capsule, the foot pedal is placed briefly into position 2 to aspirate the surface of the anterior lens capsule. Then slightly push the pedal into position 3 to deliver the single burst of ultrasound energy and then retract to position 2 to briefly aspirate liquefied lens material. If the lens nucleus has sufficient density, use the phaco tip to gently rock it to release any trapped fluid from the posterior part of the capsular bag. At this point the phaco probe can be safely removed from the anterior chamber.
With the capsular bag decompressed the risk of errant run-out is decreased and we can use our forceps to start and then finish the capsulorhexis with precision and control. The remainder of the case can be more easily completed now that there is a strong capsulorhexis. For cases of intumescent white cataract, phaco puncture can be a very useful technique to ensure a safe capsulorhexis and a great surgical outcome.
