Gas-forced infusion useful to complete phaco with anterior capsular tear

This method offers advantages such as better surgeon control and case-based customization of parameters.

Amar Agarwal

Continuous curvilinear anterior capsulorrhexis has been the method of choice for capsular entry in phacoemulsification since its introduction by Gimbel and Neuhann in 1990. It provides a strong capsular rim that resists tearing even when stretched during lens material removal or lens implantation.

In the event of a runaway capsulorrhexis, continuing with phacoemulsification carries the risk of extension of the capsular tear through the equator onto the posterior capsule. This can potentially lead to nucleus drop or vitreous loss and reduces the chances of a stable in-the-bag IOL implantation.

Multiple techniques can be used in the event of a tear. These include starting the capsulorrhexis from the opposite side to include the tear and backward traction on the base of the capsular flap, but these are not always successful.

In this column, we describe a novel technique to complete phacoemulsification following an irretrievable anterior capsular tear with the assistance of an air pump (gas-forced infusion) in cataracts with nuclear sclerosis grade 1 to 3 or white cataracts in patients under 60 years of age. The idea was conceived by Dr. Narasimhan.

Gas-forced infusion for cataract surgery was first started by Sunita Agarwal, MS, DO, in 1999 and was used to help in phakonit (bimanual phaco/microincision cataract surgery). When we started 700-µm cataract surgery (microphakonit) in 2005, gas-forced infusion again helped. Subsequently, we used it in all our coaxial phaco and micro-coaxial cases as well.

Gas-forced infusion can be external (using an aquarium fish pump) or internal (meaning the air pump is built inside the machine). A similar inbuilt device for pressurized infusion has been adapted in the new Stellaris phacoemulsification system (Bausch & Lomb). The internal forced infusion, which was first used by Arturo Pérez-Arteaga, MD, of Mexico after he read our articles on the air pump, is a welcome addition because it seems to have certain advantages, such as better surgeon control, case-based customization of parameters and avoiding the need of an additional attachment to the existing phacoemulsification system.

Surgical technique

The anterior capsulorrhexis is started as a capsular nick from the center that is then moved to the right. The capsular flap is then lifted off and teased downward. As the maximum tendency to lose the capsulorrhexis is near its completion, we are usually left with an incomplete capsulorrhexis superiorly and to the right. Since all manipulations will be directed down and to the left, the chances of the capsulorrhexis extending will be less. For a left-handed surgeon, one should start from the center and move to the left.

After an irretrievable anterior capsular tear (Figure 1), we refrain from making further manipulations that may extend the tear to the posterior capsule. If there is suspicion of posterior capsular extension of the tear, we prefer to convert the surgery to an extracapsular cataract extraction. If we decide to continue with phaco, the anterior capsule is flattened with the help of viscoelastics. We then make a nick from the opposite side using a cystotome or Vannas scissors and complete the capsulorrhexis.

Figure 1. Capsulorrhexis running away to the periphery.

Figure 2. Hydrodissection done and nucleus prolapsed into the anterior chamber. Images: Agarwal A

The viscoelastic in the anterior chamber is then expressed out to make the globe hypotonus, after which a gentle hydrodissection is done at a site 90° from the tear while pressing the posterior lip of the incision to prevent any rise in IOP. No attempt is made to press on the center of the nucleus to complete the fluid wave. The fluid is usually sufficient to prolapse one pole of the nucleus out of the capsular bag (Figure 2), or else it is removed by embedding the phacoemulsification probe, making sure not to exert any downward pressure, and then gently pulling the nucleus anteriorly. The whole nucleus is brought out into the anterior chamber, and no nuclear division techniques are tried in the bag.

Phacoemulsification can be started at this stage for cataracts with nuclear sclerosis grades 1 to 3, but it is safer to convert to an extracapsular cataract extraction for nuclear sclerosis grade 4.

Phacoemulsification is started with the gas-forced infusion in place and the bottle height 75 cm above eye level (Figure 3). The infusion is kept on continuous mode at all times. This prevents the anterior chamber from collapsing even if the surgeon takes the foot off the machine. As the entire nucleus is prolapsed into the anterior chamber and emulsified, it prevents any stretch on the torn capsulorrhexis. The gas-forced infusion provides for a deep anterior chamber, pushes the posterior capsule back and prevents surge to allow safe anterior chamber phacoemulsification.

Figure 3. Nucleus being removed by phacoemulsification after prolapsing it into the anterior chamber.

Figure 4. Irrigation and aspiration being performed in the Cap Vac mode.

While withdrawing the probe, viscoelastic is injected simultaneously through the side-port incision. Irrigation and aspiration is performed in the “Cap Vac” mode with the aspiration set at 5 mm Hg, the flow rate at 6 mL/min and the gas-forced infusion pump on (Figure 4). In the presence of a thick epinucleus, we first inject viscoelastic between the capsule and the cortical matter, 90° from the site of the tear, to express the epinuclear plate into the anterior chamber. The epinucleus is then aspirated in the anterior chamber, keeping the vacuum at 120 mm Hg and flow rate at 20 mL/min.

The cortex in the region of the capsular tear is aspirated last. The anterior chamber and bag are partially filled with a viscoelastic, and the IOL is injected, introducing the leading haptic into the bag but pointing away from the area of the tear and not directing the IOL too posteriorly. The IOL is gently manipulated into the capsular bag with the help of a Y rod (Katena – Agarwal globe stabilization rod), giving a final orientation of the haptics 90° away from the anterior capsular tear.

Air pump

The presence of a gas-forced infusion device or an air pump helps in maintaining a deep anterior chamber and pushing the iris and the posterior capsule back. A simple air pump is connected by an IV set to the needle, which is normally fixed in the glass balanced salt solution bottle. A Millipore filter is used so that no infection can occur. This allows for a safe anterior chamber phacoemulsification by creating a deep anterior chamber and removing surge. The gas-forced infusion allows a good hold on the cortical matter even at the low Cap Vac settings, allowing easy removal of cortex without surge.

In conclusion, an air pump-assisted anterior chamber phacoemulsification followed by irrigation and aspiration in Cap Vac mode and gentle IOL implantation can help safely complete a case with a torn anterior capsulorrhexis.

• Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Prof. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.