Incision Alternative for a Posterior Capsule Rupture
A bimanual pars plana vitrectomy can streamline cleanup and help provide a good surgical outcome.
LOUIS D. "SKIP" NICHAMIN, M.D.

Recent refinements in phaco and IOL surgery have led to a myriad of patient benefits including the reduction of pre-existing refractive error, improvement to the quality of vision through the use of aspheric implants, and most recently, the introduction of new multifocal and pseudoaccomodating lenses. At the heart of these advances, however, is the remarkable reproducibility of the procedure and amazingly low rate of complications.

Nonetheless, problems will be encountered occasionally such as a rupture of the posterior capsule and vitreous loss. While this is a challenging complication for any surgeon to deal with, in the setting of small incision surgery, if the surgeon adheres to certain fundamental principles and employs proper instrumentation and surgical technique, the vast majority of these complicated eyes will enjoy an outcome that differs little from that of an uncomplicated case.

An Alternative Approach

Management of a posterior capsule rupture includes quick recognition of the problem, avoidance of hypotony and maintenance of a truly closed-chamber environment. This is predicated upon the use of watertight incisions. As such, a much lower rate and volume of infusion may be used, thereby reducing intraocular turbulence. To further enhance control of the intraocular environment and reduce vitreoretinal traction, a separated or bimanual vitrectomy should be utilized.

In this way, the location and vector force of the infusion is displaced from the point where one is attempting to delicately remove vitreous. A reasonable approach is to place both instruments through limbal incisions (Figure 1 in the August issue of Ophthalmology Management). However, I believe that a much more efficient and potentially safer approach is to perform the vitrectomy through a pars incision (Figure 2  in the August issue of Ophthalmology Management).

This allows the surgeon to "pull down" prolapsed vitreous from the anterior chamber, markedly reducing the amount of vitreous that is removed from the eye. When working from the limbus and bringing vitreous up, it is much more difficult to find an end point and one often unintentionally removes a considerable portion of the vitreous body and then must deal with a hypotonous eye.

Another major advantage to working through a pars plana incision is the enhanced access one has to residual lens material. Cortex, epinucleus and even medium density nuclear material may be removed with the vitrector by gradually increasing vacuum and reducing the cutting rate. When addressing vitreous, the highest cut rate is used with the lowest possible vacuum that will permit vitreous aspiration. In this way, a more complete clean-up may be achieved, reducing secondary complications such as increased IOP, inflammation and cystoid macular edema.

It goes without saying that care and effort must be directed toward the learning and acquisition of any new surgical technique, but in reality, the pars plana approach is quite straightforward. Typically, one first takes down the conjunctiva and applies light cautery at the site of the intended sclerotomy — although some surgeons will incise directly through the conjunctiva. Due to increased vascularity the cardinal meridia should be avoided . With the posterior capsule open, infusion may be placed through a limbal paracentesis incision, or through a second pars plana incision. The clock hour of the vitrectomy incision should be selected to best access remaining lens material.

The pars plana is anatomically located between 3.0 and 3.5 mm posterior to the limbus, so most commonly the incision is placed 3.2 mm from the limbus, though an adjustment may be made for unusual axial lengths. Depending upon surgeon preference, wounds are created to accommodate either 19- or 20-gauge instruments. A dedicated disposable microvitreoretinal (MVR) blade should be used to create properly sized and therefore watertight incisions for both pars plana and limbal incisions. In creating the pars incision, the MVR blade is held perpendicular to the scleral surface and usually oriented in a limbal-parallel fashion. The blade is directed toward the center of the globe with a simple in-and-out motion.

Removal

As mentioned, when removing vitreous, the highest possible cut rate is used along with the lowest possible vacuum setting. One can titrate up with vacuum, and down on the cutting rate in order to remove remaining lens material. Attention is paid to preserve as much capsule as is possible, especially the anterior capsular rim in order to facilitate implant placement. Infusion is kept at a minimum — just enough to maintain adequate IOP. Generous use of the appropriate, different viscoelastic agents will aid in volume maintenance, further decreasing the need for infusion. A dispersive agent works best to tamponade the hyaloid face, and a more cohesive viscoelastic is used to maintain space.

Care should be taken in both cleaning and closing the pars plana incision. Choices for suture closure would include 9-0 nylon or 8-0 vicryl. Twenty-five gauge instrumentation has become available, and in some settings, these tools may allow for sutureless surgery. However, insertion requires a firm globe. These instruments can still be used in a complicated setting by first creating small incisions with a sharp blade as opposed to the usual trochar system. One downside is their lack of tensile rigidity and, therefore, an ability to manipulate the position of the globe.

Prudence would dictate that a bimanual pars plana vitrectomy should not be performed for the first time during a live complication, but rather carefully studied and first practiced in a lab setting. By abiding to these surgical principles, a salutary outcome may be obtained despite the occurrence of what remains one of the most troublesome complications of cataract surgery.

Louis D. "Skip" Nichamin, M.D., is the medical director of Laurel Eye Clinic in Brookville, PA. He can be e-mailed at Nichamin@laureleye.com.