Viscoelastic can cushion eyes with damaged zonules

Surgeons must recognize when to stop, reassess and take cautionary measures.

ByRobert M. Mandelkorn, MD

One of the most difficult and challenging cases that the cataract surgeon may confront is the patient with loose, torn or weak zonules. In many of these eyes, complications will occur. It may start with the presentation of vitreous in the anterior chamber and eventually result in the loss of the lens into the vitreous. A vitreoretinal surgeon will then have to retrieve the lens from the retina.

In the past few years, there have been a number of advances for the treatment of this problem, including suturing the lens capsule to the sclera, iris hooks to stabilize the capsular bag during surgery and the development of capsular tension rings. Each of these concepts has its own problems.

In the case of suturing the lens capsule to the sclera, the capsular bag can be torn during suturing, making a tenuous situation even worse.

Iris hooks can stabilize the capsular bag; however, in many cases the capsular bag is so weakened during surgery that it must be sutured to the sclera in order to safely hold an IOL implant, again resulting in the possible tearing of the capsular bag.

The most ingenious attempt to deal with weak or missing zonules has been the development of capsular tension rings. While initial clinical trials have been promising, these devices have not been approved by the Food and Drug Administration for use in the United States on a widespread scale.

Few options

At this time, the surgeon, when presented with weak or missing zonules at the time of cataract surgery, has few viable options. As an alternative, I think that if this problem is recognized at an early stage, it can be safely addressed with only minimal complications.

However, in many cases when the surgeon first observes this problem, there is a tendency to continue with the surgery with the hope that this problem will be limited and not progress. Unfortunately, during every stage of cataract surgery, from capsulorrhexis to hydrodissection through phacoemulsification of the lens, the disruption of the lens zonules can progress, resulting in a rapid worsening of a tenuous situation.

It is my impression that most of the surgeon’s troubles begin with the presentation of vitreous in the anterior chamber, and if this can be avoided, the surgery will go a lot easier for the patient and the surgeon.

Specifically, when the surgeon first notices that zonules are weak or disrupted, such as with extreme laxity of the lens during capsulorrhexis or a sudden deepening of the anterior chamber during phacoemulsification, the surgeon should immediately stop at that point and assess the situation.

Minimize further harm

If the surgeon thinks that zonules are compromised or disrupted, every effort should be made to minimize further harm to the eye. Specifically, at this time the eye should be filled with a high molecular weight viscoelastic substance. During this procedure, the blunt-tipped cannula used to fill the anterior chamber with this substance can also begin to gently sweep under the lens capsule, separating the posterior lens capsule from the anterior vitreous face. In the process, it will spread a layer of viscoelastic substance between the posterior lens capsule and the anterior vitreous face.

To further help this procedure, the lens is gently turned either clockwise or counterclockwise with an instrument as simple as a cyclodialysis spatula to slowly release the remaining zonules and to safely bring the lens into the anterior chamber. At the same time, the viscoelastic substance is still being injected between the lens and the anterior vitreous face. Eventually, the lens will be safely delivered into the anterior chamber with a strong coat of viscoelastic substance between it and the anterior vitreous face.

The wound is then enlarged and the lens is easily expressed from the eye with either a lens loop or gentle pressure upon the posterior lip of the wound and counter pressure upon the cornea 180° away.

The surgeon will find the layer of viscoelastic substance has protected the anterior vitreous face, which is now intact. The wound can then be safely closed, and the surgeon can then decide whether to implant an anterior chamber lens or suture a posterior lens into the eye.

With this technique, it has been my clinical impression that many of the complications observed in these eyes can be avoided with a successful and positive outcome.

While there are a number of interesting treatment options in the literature, it is my belief that this simple technique, available to all eye surgeons, can make this potentially dangerous situation easier to manage with fewer risks and complications.

For Your Information:
Robert M. Mandelkorn, MD, can be reached at Veterans Affairs, Outpatient Clinic, 3033 Winkler Ave Extension, Fort Myers, FL 33916 U.S.A.; +1-239-939-3939, ext. 6283; fax: +1-239-267-3759. Dr. Mandelkorn does not have a financial interest in any of the products or devices mentioned in this article.