Proper planning critical for preventing and managing posterior capsule rupture

New Orleans

-Posterior capsule rupture (PCR) is mostly preventable, but even when it occurs, a good outcome still can be achieved with proper management, said Dennis S.C. Lam, MD, at the annual meeting of the American Academy of Ophthalmology.

"Don't panic if the posterior capsule tears," said Dr. Lam, chairman, Department of Ophthalmology and Visual Sciences, Chinese University of Hong Kong, Hong Kong. "Assess the situation thoroughly so that you can develop a good strategic plan to prevent additional complications."

 Knowing the risk factors for PCR can help surgeons develop a surgical plan to minimize the risk of a tear. Myriad features can increase the likelihood of a PCR, including patient factors, ocular factors, lens factors, surgical factors, and surgeon factors.

"By recognizing these risk factors and taking good care to address them when possible, most cases of PCR could be avoided," Dr. Lam said.

Early recognition

When PCR occurs, early recognition is critical to enable prompt implementation of damage control steps. The first measures for management aim to maintain anterior chamber depth, because shallowing will promote extension of the PCR and increase the likelihood of vitreous prolapse or loss. Therefore, before removing any instruments from the eye, additional viscoelastic should be injected.

Once the anterior chamber has been stabilized, surgeons should take a few seconds to assess the situation and develop the surgical plan. Factors to consider include the size, shape, location, and extent of the PCR, whether vitreous loss or dropped fragments have occurred, and the stage in the surgery when the complication appeared.

Dr. Lam suggested having a low threshold for conversion to extracapsular cataract extraction if the rupture occurs early in the case, i.e., at any time through the early stage of phacoemulsification, and especially when there are large nuclear fragments.

"Delivery of these fragments with a vectis and viscoexpression can usually be done safely and effectively," Dr. Lam said.

Minimize losses

When PCR has occurred without vitreous loss, surgeons should be very generous with the viscoelastic because it can help plug the rupture to minimize vitreous prolapse and protect the corneal endothelium. In those eyes in which medium to small fragments exist, it may be possible to continue the case successfully and complete it through to lens implantation using phacoemulsification and dry aspiration/viscoexpression to remove residual cortex and nuclear fragments. Appropriate phaco settings are important, however.

"This situation calls for a low bottle height between 20 and 40 cm above the patient's head, low aspiration flow rate ranging from 10 to 15 ml/min, low ultrasound power between 20% and 40%, and high vacuum in the range of 120 to 200 mm Hg," recommended Dr. Lam.

 If the rupture occurs later and medium or small fragments with vitreous loss but no dropped fragments are present, the surgeon should inject viscoelastics beneath and around the nuclear fragments and perform dry anterior vitrectomy to free the nuclear fragments from surrounding vitreous, he said. The case can then be completed using phaco with the previously mentioned settings and dry aspiration/viscoexpression to remove residual cortex and small fragments.

Timely referral to a vitreoretinal specialist is appropriate for management of conditions in which vitreous loss with dropped fragments has occurred. Posterior assisted levitation (PAL), a technique introduced by the late Charles Kelman, MD, may be considered to elevate dislocated fragments into the anterior chamber. This method, which uses a spatula introduced behind the posterior capsule through a pars plana incision, is somewhat controversial because of its potential complications, which include retinal tears, vitreous hemorrhage, and retinal detachment, however.

"Consider PAL very carefully and only for selected patients. Never perform PAL in an uncooperative patient, and if you do use it, don't go too far or too deep with the spatula to avoid damaging the retina," Dr. Lam said.

Further advice

Providing additional tips on surgical considerations for cases in which PCR has occurred, Dr. Lam noted that when performing anterior vitrectomy, the phaco probe should not be used for vitreous cutting, and sponge vitrectomy should be reserved only for checking incarceration of vitreous strand over the side ports. He also cautioned against using coaxial infusion when performing anterior vitrectomy and taking care to note the direction of the infusion stream using a bimanual technique.

"When using coaxial infusion, the fluid flow will stretch and enlarge the PCR and the fluid will also hydrate, expand, and flush the vitreous from the back of the eye to the front. With the bimanual technique, take care that the flow is directed into the anterior chamber and not into the vitreous," he said.

Anterior vitrectomy should be performed until the offending vitreous is removed to the level of and just below the posterior capsule, and a dry technique is very useful, Dr. Lam said.

"To minimize anterior chamber fluctuation, surgeons may want to use the side ports and refill the eye frequently with viscoelastic," he said.

Triamcinolone for staining the vitreous can be a helpful aid for enhancing visualization, but if it is used, it should be injected carefully to avoid it getting into the posterior vitreous.

Pupil constriction is performed at the end of surgery to detect vitreous incarceration at the corneal/scleral wound manifesting as an irregular or peaked pupil. If present, it can be managed with sponge vitrectomy and mechanical separation.

Lens implantation should be performed whenever possible, and in-the-bag implantation is preferred. Decisions about lens implantation depend on the size of the posterior capsule tear, the integrity of the anterior capsule rim, and whether the patient needs referral to a vitreoretinal surgeon for management of retained lens fragment, however.

"Leave the eye aphakic if removal of fragments through the anterior route is anticipated," Dr. Lam said.OT