February 2012

 

NEWS & OPINION

 

Tools and techniques

Phacoemulsification in the white cataract


by Nick Mamalis, M.D.

 

Kevin Miller, M.D.

The types of cataracts that pose the greatest challenge to the ophthalmologist include the dense brunescent cataract, the white cortical cataract, and the posterior polar cataract. Each type is unique in the specific surgical challenge it poses and the complications that may result.

There is a spectrum of behavior for white cataracts. Most of the time they pose no particular threat. However, sometimes they are challenging and require a special approach. The latter occurs when a white cataract is intumescent. An intumescent cataract is one that is swollen or congested. The term is often used in reference to substances that swell in response to heat or flames, such as passive fire retardants. In the case of the cataractous lens, intumescence refers to swelling or hydration associated with increased intralenticular pressure.

The problems posed by the white cortical cataract are two-fold. First, it is often difficult to visualize the anterior capsule to perform a capsulorhexis because there is no contrast against the backdrop of a white cataract. Second, the lens capsule may rupture like a balloon when the initial capsule puncture is made.

In this issue, Dr. Mamalis discusses his approach to improving visualization of the anterior capsule, performing a successful capsule puncture and capsulorhexis, and completing the phacoemulsification of a white cataract without complications.

Kevin Miller, M.D., complicated cataract cases editor

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white, intumescent cataract

Figure 1. Sagittal section of a globe with a white, intumescent cataract

Anterior capsular tear Figure 2. Anterior capsular tear extending to the equator with trypan blue dye demonstrating the Argentinian flag sign

Capsular puncture Figure 3A. Capsular puncture with a sharp cystotome demonstrating a white plume of liquified cortex

Phacoemulsification Figure 3B. Same patient following aspiration of liquified cortex under the anterior capsule decompressing the lens Source: Nick Mamalis, M.D.

One of the most difficult anterior segment procedures to perform is the removal of a white cataract. A mature white cataract may actually have a hard or brunescent nucleus underlying it with a flocculent anterior and posterior cortical opacity. The trickiest white cataract to remove is a hypermature or intumescent-type cataract (Figure 1). These cataracts have markedly hydrated swollen lenticular material, which then causes an increase in lens thickness and a relatively tense lens capsule. In the extreme circumstance, the cortex can completely liquefy and allow the dense nucleus to sink to the bottom of the capsular bag, forming a morgagnian cataract. The most difficult step of cataract surgery in these hypermature intumescent cataracts is performing a capsulorhexis or continuous curvilinear capsulorhexis (CCC) without an extension upon the opening of the capsular bag. The white cataract prevents a red reflex that does not allow adequate visualization of the capsule when performing a CCC. Staining of the anterior lens capsule with a stain such as trypan blue is very helpful in allowing visualization of the capsule without an adequate red reflex. A small stab incision is made at the limbus and air can be inserted into the anterior chamber with trypan blue injected under the air. It is important to paint the anterior capsule in a back and forth movement similar to a windshield wiper when placing the trypan blue. A second way that the capsule can be dyed is a soft shell technique with an OVD injected into the anterior chamber and then a thin layer of balanced salt solution placed on the capsule with the trypan blue dye placed on the lens capsule in this manner. When air is used, the air is then replaced with OVD following staining of the capsule. A high molecular weight or a super cohesive OVD such as Healon5 (Abbott Medical Optics, Santa Ana, Calif.) or DisCoVisc (Alcon, Fort Worth, Texas) is recommended in the intumescent cataract. This will help to flatten the dome of the capsule and keep the anterior chamber pressurized without leakage of the OVD out of the anterior chamber during the performance of the capsulotomy. If there is any high pressure it is important to avoid puncturing the capsule with a large forceps, as this may cause an uncontrolled tear with the so-called Argentinian flag sign, in which the white cataract is seen in the center and the blue stained capsule on both sides with a tear extending to the equator (Figure 2). This can be minimized by using a sharp cystotome to begin the CCC with a very small puncture of the capsule and immediate aspiration of the liquified cortex underneath the anterior capsule to help decompress the intumescent lens (Figure 3A, 3B). Another way of decompressing the lens is to make a small puncture in the anterior capsule using a sharp 27-gauge needle and aspirate out the anterior liquified cortical material. In addition to liquefaction of the anterior cortical material, there is also liquified material seen in the posterior cortex, so it is important to gently depress the lens once you have made a small opening to try and allow some of the liquified material to come forward. Once decompression has been performed, the capsulotomy can be done safely using an Utrata-type forceps or a microforceps through the stab incision. As there still may be some posterior pressure causing forward bowing of the lens, it is important to perform a relatively small capsulorhexis initially and to replace the highly retentive viscoelastic in the anterior chamber of the IOL to continually flatten the capsule and try to prevent the capsule from extending outward. Once an adequate CCC has been completed, then the phacoemulsification handpiece may be used to remove the liquified cortex and epinuclear material in order to adequately assess the hardness of the lens nucleus. In cases where much of the cataract has been liquified, the nucleus may be relatively soft and easy to remove using a standard vertical chopping technique. When there is a large, relatively brunescent nucleus present, there is often very little cortex or epinucleus present, which usually helps to stabilize the nucleus within the capsular bag. This nucleus may become relatively mobile, and the fact that there is little cortex behind the nucleus leaves little margin for error in terms of the posterior capsule. A high vacuum setting may be used to impale the nucleus, and a vertical chop may be used to break off small pieces of the nucleus, which will then allow them to be brought into the plane of the iris with phacoemulsification. The harder the nucleus, the greater the number of fragments that should be chopped, allowing safe phacoemulsification. Standard irrigation/aspiration can then be performed with removal of any remnant cortex as well as any fragments adherent to the capsular bag. A standard IOL may then be placed within the capsular bag.

In conclusion, it is imperative that the surgeon be aware of the various types and presentations of white cataracts. Anterior capsular dyes such as trypan blue are an excellent adjunct to allow adequate visualization of the capsule in these white cataracts. An intact CCC is critical, and careful attention to technique must be paid in order to prevent splitting or running out of the anterior capsule. Once an adequate capsulotomy is performed, the difficulty of the remaining surgical procedure depends on the hardness of the lens nucleus. Often, straightforward or routine phacoemulsification is possible on these hypermature cataracts once the lens is decompressed and an adequate capsulotomy is performed.

Editors' note: Dr. Mamalis has no financial interests related to this article.

Contact information

Mamalis: nick.mamalis@hsc.utah.edu

Phaco in the white cataract Phaco in the white cataract
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