A novel approach to a perplexing problem.
BY SINA J. SABET, M.D., F.A.C.S.
All cataract surgeons have experienced the dreaded scenario of a dropped lens. Things have been going smoothly all day when suddenly you begin to notice a deepening posterior chamber during phacoemulsification. The nuclear fragments become harder to follow with the hand-piece and it becomes more difficult to rotate and manipulate them. Before you can begin to institute a plan of action, the lens fragments slip into the mid-vitreous and quickly out of view.
Although fortunately rare, the potential for this complication can have us waking up in a cold sweat in the middle of the night. For those who work with residents and other surgeons during the early part of their learning curve, we may see this more frequently than we would like. Much of the anxiety comes from the quick decision-making that is required in these situations.
Should we let the lens go or make some attempt at retrieval? Anxiety also comes from the question of how to approach the counseling of the patient and his or her family. Cataract surgery can be an extremely anxiety-provoking experience for patients, even without complications. This is compounded by the extremely high expectations that modern cataract surgery has created for our patients. Most expect perfect vision even on the first postoperative day. In this article, I will discuss the problems presented by dropped lens fragments and the use of the instrument that I have invented to address this situation.
Assessing the Surgeon’s Options
When there is a dropped lens and the patient begins to experience elevated pressure, inflammation and cloudy vision, the anxiety levels can overwhelm the patient, as well as the family. The time it takes for many vitreoretinal surgeons to schedule surgery to retrieve the fragments can seem like an eternity to the patient, as well as the initial surgeon. The attendant resentment and hostility towards the cataract surgeon can be significant. This situation requires extremely honest, open and tactful communication on the part of the surgeon. He or she will need to closely guide and follow the patient through possible prolonged cystoid macular edema, corneal edema, glaucoma, retinal tears and detachments, and other vision-threatening complications.
Most of us have a mentally well-rehearsed plan of action for such scenarios. Perhaps the safest is simply to let the lens fall back into the vitreous, perform a limited anterior lensectomy, clean up residual cortical material and decide on whether to implant an intraocular lens.
Although this is an appealing option, I have seen in practice that many experienced anterior segment surgeons cannot avoid the temptation to go after the fragments, many times in a surprisingly aggressive manner. I suspect their motivation is to avoid the complications mentioned above if they can do anything at all to salvage the case. There is no specialized instrumentation for approaching these cases, and when videos of such surgeries are shown in various meetings, one can very noticeably see the vitreoretinal surgeons in the audience wince and cringe.
Techniques that are often used by these more aggressive anterior segment surgeons include bringing the lens fragment in front of the iris and either enlarging the incision to remove the lens in an extracapsular manner, or placing a Sheets glide to support the fragments for further vitrectomy and phacoemulsification. The late Charles Kelman, M.D., the father of modern phaco, proposed the PAL (posterior assisted levitation) technique, where a second instrument is placed, often through a pars plana incision, behind the lens fragment, to bring up the lens fragment into the anterior chamber for further phacoemulsification.1 More recently, David F. Chang, M.D., has suggested viscoelastic levitation to stabilize the nuclear fragments.2 Both the PAL technique and the Chang modification seem to be reasonably safe, as shown in controlled studies.3
|“When attempting the PAL technique, a single narrow instrument is often insufficient to stabilize all fragments. Even a single fragment can wobble and fall off the sides.”|
In practice, these techniques can be challenging with current instrumentation. As they say in the military, “no plan survives first contact with the enemy.” When attempting to implement the PAL technique, if there are multiple fragments, a single narrow instrument like the cyclodialysis spatula is often insufficient to stabilize all fragments. Even if there is only a single fragment, it can very easily wobble and fall off to the sides. Similar concerns exist for viscoelastic-assisted levitation.
My own invention, the Sabet Lenticular Safety Net (Rhein Medical, Tampa, Fla.) was designed with these concerns in mind. Since its introduction, the Sabet Lenticular Safety Net has generated a fair amount of interest. This instrument is designed to aid the anterior segment surgeon in the management of dropped nuclear fragments intraoperatively. Because of the number of questions raised on its use, and its continued unfamiliarity to many surgeons, I would like to explain how it can serve as an additional tool in the surgeon’s armamentarium.
The Safety Net Concept
The Safety Net, in the closed position (Figure 1), can keep the advantage of the cyclodialysis spatula in being able to fit through a very small incision. This may be through a pars plana incision, or if speed is of the essence, through the pre-established paracentesis incision at the corneal limbus. The advantage of this instrument becomes noticeable, however, once it is inside the eye.
Figure 1. The Sabet Lenticular Safety Net in a side profile in a closed position.
When the button on the side of the instrument is lowered, four very thin wires exit the instrument (Figures 2, 3) in a radially expanding manner. This provides a plane, rather than a single rod, on which to support the lens fragment(s). Additional features of the design include a broad spoon- or bowl-shaped configuration, as well as a small upturn at the end of the wires. This upturn both protects the retina from the edge of the wires if it is inadvertently touched, and acts like a “claw” to hold onto the lens fragments. The thinness of the wires minimizes the surface area that can place traction on the vitreous gel.
Figure 2. Top view of the Lenticular Safety Net, in open position. The radially expanding wires provide a broad surface area for maintaining lens fragment(s).
Figure 3. Side view of the Lenticular Safety Net. The bowl shape of the wires and the upturn at the tips provides traction to stabilize fragment(s).
A limitation is that one of the surgeon’s hands will be occupied with holding the net in place, so techniques such as two-port vitrectomy cannot be used, at least as long as the net is inside the eye. A viscodispersive agent may be used to push away adherent vitreous from the back of the fragments. Of course, this may also be done before the net is deployed. This will depend on the actual surgical situation as it is unfolding. The bottle height should be lowered as soon as the posterior capsular tear is recognized, so that the lens fragments are not pushed into the vitreous cavity.
Once the lens fragments are stabilized in this way, how to proceed then becomes the surgeon’s prerogative. One possibility is that the fragment(s) can be brought up into the anterior chamber, and a Sheets glide placed behind it. This technique will free up both hands to enlarge the incision and remove the fragments via an extracapsular technique. Al tern atively, single-port vitrectomy can be done to remove adherent vitreous.
Because the lens fragments are stable, the vitrectomy can be performed posterior to the instrument as well. If the lens fragments are soft, vitrectomy can continue to remove the lens fragments. If it does not appear that there is much vitreous in the anterior chamber, a “slow-motion” phacoemulsification can be performed. This low-flow, low-aspiration, low-irrigation technique minimizes turbulence and keeps the fragments from possibly getting dislodged from the net, as well as keeping the vitreous from coming forward. Once the fragments are removed, the case can be completed as with any case of a ruptured posterior capsule without lens fragments.
As with any surgical technique, the surgeon’s judgment on when to use this instrument is indispensable. For example, the surgeon may forgo this technique in patients with a history of retinal tears and detachments, macular holes, in high myopes, and those with lattice degeneration or other retinal pathologies.
It is also advisable to counsel the patient and family postoperatively about the surgical complication, and possibly have a vitreoretinal specialist look at the retina within a few days after surgery to ensure that there are no retinal issues. The retina specialist may want to follow the patient for a few months along with you. I have found that the patient and family are much more accepting of this scenario, however, than one where they will definitively need a second surgery by the retina specialist. The emotions seem to be less raw when you can inform them that the surgery was completed and the intraocular lens placed, and that there is only a possibility of future risks.
In summary, the Sabet Lenticular Safety Net allows for a modification of the PAL technique to allow a more secure removal of lens fragments in cases of posterior capsular rupture. OM
1. Kelman CD. Posterior capsule rupture: PAL technique. Video J Cataract Refract Surg. 1996;12: no 2.
2. Chang DF, Packard RB. Posterior assisted levitation for nucleus retrieval using Viscoat after posterior capsule rupture. J Cataract Refract Surg. 2003 Oct;29:1860-65.
3. Por YM, Chee SP. Posterior-assisted levitation: outcomes in the retrieval of nuclear fragments and subluxated intraocular lenses. J Cataract Refract Surg. 2006 Dec;32:2060-63.
Dr. Sabet is in private practice in Alexandria, Va. He is assistant professor of Ophthalmology and Pathology at Georgetown University Medical Center. As the inventor of the Sabet Lenticular Safety Net, he has a financial relationship with Rhein Medical.