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Equalize pressure gradient to maintain control during removal of intumescent cataract
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There are many challenges associated with phacoemulsification of intumescent white cataracts: The opaque lens material blocks the red reflex and hinders visualization of the capsule, the nuclear material may be quite dense, and there is a tendency for the capsulorrhexis to become errant, which can result in complications such as vitreous prolapse.
Using trypan blue dye, we can stain the anterior lens capsule to aid in visualization during capsulorrhexis creation. With phaco power modulations and variants of the phaco chop technique, we can safely remove even dense nuclei while limiting the ultrasonic energy used. But perhaps the biggest challenge is avoiding the runout of the capsulorrhexis, which can result in the “Argentinian flag sign.” This syndrome gets its name from the appearance of the capsule and cataract after the capsulorrhexis has been lost and three stripes appear: a middle stripe of white cataract flanked by the remainder of the anterior capsule, which has been stained blue.
Images: Devgan U
We can avoid losing control of the capsulorrhexis by managing the pressure gradients that exist within the capsular bag. For an intumescent cataract, the cortical lens material has become white due to denaturing of lens proteins and it has become liquefied, hence the name intumescent. With this fluid within the capsular bag, it becomes more challenging to perform the capsulorrhexis as compared with operating on a solid cataract.
Techniques have been described to release this fluid, such as using a sharp needle to pierce the anterior lens capsule and then aspirating via a syringe or using the phaco probe to puncture a round hole in the anterior lens capsule to remove fluid before capsulorrhexis creation. Both of these techniques will work because they release the pressure gradient that exists within the capsular bag. My preferred technique allows the surgeon to be in control of the pressure within the anterior chamber as well as in the capsular bag, and it gives great control during capsulorrhexis creation.
With a single paracentesis incision made in the eye of 1 mm or less in width, the anterior capsule is stained with trypan blue dye and then the anterior chamber is filled with viscoelastic. The key at this point is to ensure that the anterior chamber is highly pressurized, more than in a typical cataract surgery. We need to make sure that the pressure within the anterior chamber is higher than the intracapsular pressure that is created due to the trapped liquefied cortex.
We must not make the main incision just yet because due to its size of 2 mm to 3 mm, it will allow viscoelastic to escape from the anterior chamber and the pressure will not be maintained. Instead, use a cystotome or bent needle to enter the anterior chamber via the same small paracentesis incision that was made earlier (Figure 1). This small incision is tight enough that viscoelastic will not escape from the anterior chamber, and the high pressure will be maintained.
Now we can use the cystotome to puncture the anterior lens capsule to start the capsulorrhexis. Placing this cystotome on the viscoelastic syringe will allow the surgeon to inject more to maintain the anterior chamber pressure. Now for the most critical part of the procedure: The nucleus is then rocked back and forth using the cystotome in order to free up all of the cortical fluid that surrounds it (Figure 2). If the cortical material begins leaking into the anterior chamber, which would appear as a milky fluid oozing up through the anterior capsular opening, more viscoelastic must be injected.
Once the nucleus is freely mobile and there is no more trapped fluid noted, it is acceptable to have some of the milky fluid drift into the anterior chamber. At this point the main incision can be made with the keratome (Figure 3). Because the intracapsular pressure gradient has been released, there is little danger of an errant capsulorrhexis. The capsulorrhexis forceps can now be used via the main incision to complete the opening, which should be round and continuous (Figure 4). Nucleus removal can now proceed normally, and the IOL can be placed within the capsular bag.
Other options include using a femtosecond laser to create the anterior capsulotomy. This works well because the eye is closed and the incisions have not yet been made. The femtosecond laser can create the anterior capsulotomy in just a second or two while maintaining the anterior chamber pressure so that the intracapsular cortical fluid does not have a chance to push on the nucleus and induce a pressure gradient.
Intumescent cataracts can pose surgical challenges, but with careful planning and an understanding of the pressure gradients, we can achieve an excellent outcome in a safe manner. In terms of surgeon satisfaction, performing cataract surgery for a patient with intumescent cataracts is the highest because we are literally taking a patient from blindness, often hand motion vision or less, to outstanding vision in the course of minutes.
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- Uday Devgan, MD, is in private practice at Devgan Eye Surgery, Chief of Ophthalmology at Olive View UCLA Medical Center and Clinical Professor of Ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: devgan@gmail.com; website: www.DevganEye.com.
Disclosure: Devgan reports no relevant financial disclosures.