Cataract surgery with zonular problems (2023)

ÖOne of the many challenges cataract surgeons sometimes face is weak or absent zonules, a situation often associated with pseudoexfoliation. (We know that pseudoexfoliation not only affects the zonules but can also infiltrate and affect the ciliary body; this combination can result in zonulopathy.) Here I would like to share some of the strategies I use to minimize complications during surgery - and postoperatively - when working with such patients.

Look for warning signs

One of the reasons zonular weakness is challenging is that it is not always obvious prior to surgery that the problem exists. Sometimes the signs on the slit lamp are subtle and easy to miss. For example, you may not notice a small amount of white fibrillar material on the iris or anterior lens capsule.

If the problem is mild enough, it's even possible to miss it during surgery. One study found that years after their cataract surgery, 70 percent of patients with subluxated IOLs had a pseudoexfoliation that was not discovered or noted in the original surgeon's notes. For these reasons, I take the advice of my former colleague, the late Alan Crandall, MD: Assume that every cataract surgery patient with a family history of glaucoma has pseudoexfoliation. (As I tell my residents, there is no such thing as "routine" cataract surgery.)

During a routine exam, you can find signs that a patient has a pseudoexfoliation problem. For example, you may notice an unusual discrepancy, such as B. an asymmetry between the eyes in the anterior chamber depth or an indication of a subluxation of the lens. Deposits of fibrillar material on the anterior lens capsule or sphincter are clues, and phacodonesis or iridodonesis, poor dilatation, abnormal lens or iris movements, and a small pupil are other warning signs. Any discrepancy that cannot be explained should alarm you. In this situation, you need to be prepared for possible problems.

Perhaps more important is any direct evidence of weakened zonules, particularly at the lens equator. You may be able to see focal areas of invagination of the lens capsule, particularly with dilatation. Whenever there is focal weakening of the zonules—particularly when there is loss of zonules—the capsule is not stretched evenly. The lack of stretch in an area results in a dip, and areas still under stretch can form a hump, creating a jagged edge with hills and valleys. The valleys mark areas of zonular weakness or loss. This is a classic jagged lens rim and indicates that you will have a problem at the time of capsulorhexis.

Respect the Zonules

In most cases of pseudoexfoliation, the surgery goes very well despite the problem. However, if you see a sudden deepening of the chamber, this indicates the presence of zonulopathy. That should set in motion a whole host of strategies to minimize the likelihood of a potential negative outcome.

The fact is that during cataract surgery, zoulopathy can easily be aggravated. Therefore, we must take some essential precautions to avoid this. Essentially, we need to minimize the tension we create in the x-axis or the y-axis by minimizing the sideways and up and down motion of the capsule-pocket-zonula complex. This will avoid damaging the weakened zones more than they have already been weakened. To achieve this, a stable anterior chamber must be maintained; Perform careful hydrodissection/delineation; Using tangential forces during phaco and lavage/aspiration rather than radial; and slowly and gently inserting and rotating the IOL.

Here are some specific strategies to help protect the zones:

•Be sure to dilate a small pupil.It is impossible to perform safe surgery if you cannot see well. (Of course, this is a problem you may face, whether or not the patient has pseudoexfoliation or weak zonules.) You can use a cohesive viscoelastic of your choice to viscodilate the pupil; Some surgeons recommend a hook-type push-pull technique to widen the opening. Some surgeons use scissors to perform small micro sphincterotomies that relax the pupil. Irish hooks or a device like the Malyugin Ring are other options. (If you're using a Malyugin ring, consider placing one of the circular scrolls just below your keratoma incision; this may help prevent the iris from exiting through the incision.)

•Make sure your capsulorhexis is not too big or too small.In order to minimize the loading forces in the x-axis, you need a sufficiently large capsulorhexis - at least 5.5 mm. If the capsulorhexis is too large, the edge of the capsular tear may not be above the edge of the optic. If it is too small, phimosis and shrinkage may occur over time, causing stress on the zonules at the equator and accelerating zonulopathy 360 degrees.

A small capsulorhexis also makes it difficult to perform the surgery in a way that reduces zonular stress during surgery. For example, if you can elevate the endonucleus to the anterior chamber and phacoize it there instead of into the capsular bag, you will prevent all the forces associated with phacoemulsification from acting on the zonules, but if the capsulorhexis is small, it will be very difficult to do that.

One strategy I have found helpful when creating a capsulorhexis is to use Microsurgical Technology (MST) forceps. They have ruler markings starting at the tip that can help the surgeon create an ideally sized capsulorhexis opening by confirming the diameter of the capsulorhexis you are making. (See image.) I measure it after creating the capsulorhexis. If necessary, you can always enlarge it.

MST forceps with ruler markings can help a surgeon confirm the size of the capsulorhexis. (Note the scroll of the Malyugin ring placed just below the keratoma incision; this helps prevent iris prolapse through the incision.)

•Consider implanting a one-piece IOL.A one-piece IOL unfolds very slowly without causing much tension; This gives you time to align the haptic in the desired plane and axis. It's very zone friendly. In contrast, the haptic of a three-piece lens opens very quickly; the lens pops out of the lens injector. I have no evidence that a one-piece or three-piece lens gives better pseudo-exfoliation results, but they open differently. A one-piece lens gives you more control, allowing you to avoid zonular stress.

•Perform thorough hydrodissection and hydrodelineation.You should not attempt to rotate the lens nucleus in the pouch unless you have complete separation of the capsular/zonular apparatus from the cataract itself; That is why it is very important to perform a very good hydrodissection. Note: A fluid wave is not enough to complete a spin. I say to residents: The goal is to direct this fluid force so that it separates the core material from the lens capsule at the equator.

I like to use the Chang cannula for this part of the surgery; it has a 90 degree angled flat tip. Because of the cannula design, I can begin hydrodissection just below my keratoma incision temporally, below the capsulorhexis rim, and continue irrigating upward; then I do the same in the other direction, starting again near the incision.

I also use the cannula to ensure the hydrodissection is complete. The distal tip of the beveled tip can be used to impale and rotate the lens in the pouch. Usually the hook lies parallel to the plane of the cataract; I rotate it 90 degrees and embed it in the cataract and then rotate it. Once I get good rotation, I know I've separated the lens from the capsule-zonule complex.

•If you are dealing with a pronounced zonulopathy, perform a viscodissection.This not only separates the cataract, but also lifts it out of the pouch. If the cataract is soft enough, you can perform hydrodelineation to separate the nucleus from the epinuclear and cortical material and create the ring sign. Then, because I'm right-handed, I go in with my left hand with a flat instrument while viscoelastic raising that piece into the chamber with my right hand. Next, I phacoemulsify the nucleus. Finally, I follow up the remaining equinuclear and cortical material with additional extracortical viscodissection.

•Do not press when molding.Residents and glaucoma patients often want to insert the phaco handpiece into the cataract. Instead, let the phaco tip guide you. When you perform a longitudinal phaco, the device clears the way for you without pressing. Think of it like mowing the lawn with an automatic lawn mower. The mower will pull you in the direction you are cutting the grass. It guides you; you don't do it

When you push while sculpting, you pull on the zonules in the subincisional space, pushing the entire lens-zonule complex 180 degrees away from you into the zonules. You want to minimize that stress. So let the phaco handpiece do its job. And when you're done, don't come back with the phaco. This minimizes damage to the corneal endothelium.

•Provide a stable chamber.The aim here is to minimize the forces in the y-axis by preventing the chamber from flattening or collapsing. Strategies that can help achieve this include:

—Make a 2 to 2.2 mm keratoma incision.If you make the incision 2.4mm or larger, I believe the chamber will collapse no matter what you do. So make the incision tight around your phaco and irrigation/aspiration cuffs. They want a very controlled environment.

—Make your incision triplanar.I also tell residents that when you make your keratoma incision, it cannot be biplanar. In the presence of zonulopathy, the lens and iris can move. But if you make a nice 2.2mm three-planar incision, nine times out of ten the chamber will barely shift.

—Avoid pressure changes when moving instruments in and out of the eye.I use my 27-ga. Cannula to firmly inject BSS into the chamber while simultaneously turning off the continuous flush in my phaco handpiece and carefully withdrawing it very slowly. This strategy accomplishes two things. First, the iris will not follow you through the keratoma incision since the flush is off. Second, the BSS keeps the chamber in shape, so you don't get a trampoline effect and sudden anterior chamber collapse, which could have very problematic effects on the zonula. (Note: This strategy works partially because I use a 2.2mm keratoma incision.)

Another way to maintain a stable anterior chamber is to inject viscoelastic while turning off the irrigation/aspiration. Once I have a stable chamber, I place my I/A handpiece in the eye; I remove the cortical and epinuclear plate if present; I can even remove some of the debris under the anterior capsule that can contribute to phimosis. With the other hand I go under the I/A tip while it is still irrigating and then under the rim of the capsulorhexis. (See picture above.) Then I fill the pouch with viscoelastic while turning off the I/A. (If you leave it on, some of the viscoelastic will be sucked in.)

One way to maintain a stable anterior chamber is to inject viscoelastic while turning off the irrigation/aspiration. Here, viscoelastic is injected into the capsular bag, creating a liquid wave; the I/A handpiece is kept in view when the irrigation is off.

I do not want to remove the I/A handpiece during this process as it could collapse the chamber. Instead I leave it in, almost like a placeholder for the anterior chamber. Once the entire pouch is filled and the viscoelastic bulges into the anterior chamber, I carefully remove the I/A handpiece and the chamber is serviced.

•Peel tangentially, not radially.When I need to peel the cortex off the lens capsule, for example during the divide and conquer technique, I peel it in a tangential direction, like peeling the peel off an orange after slicing it into pieces. When you drag radially, you drag the zones. I take my phaco handpiece and impale the desired piece without phacoizing it, and then I vacuum strip the tissue from an edge that has already been hydrodissected. This minimizes damage to the zones.

The tangential approach is critical and sweeps from side to side. I say to the residents, go to the west coast and walk to the east coast and peel everything. With the radial peel, you go under the rim, grab a piece of cortical or nuclear material, and pull it toward the center; which pulls directly on the zones. Tangential peeling minimizes this.

•Consider using two instruments when rotating the cataract.If you're using the divide and conquer technique, you'll want to make sure you rotate the entire lens before you start sculpting. but rotating the material with one hand puts significant stress on the zones. By adding a second instrument to assist the phaco handpiece in rotation, most of the zonular stress can be eliminated. For example, push on one half-core while pulling the other half-core in the opposite direction. This will help you maintain control in the bag during the spin and minimize stress on the zones.

•If needed, use irish hooks to stabilize the capsule during surgery.Sometimes you may find that the entire capsular bag complex is weak. In some patients, there is such a pronounced zonulopathy that you can start partial capsulorhexis and worry that the rest of the sac will collapse. In this situation, you can use irish hooks to support the capsulorhexis itself (instead of the iris). This can minimize stress on the y-axis while performing your phacoemulsification.

If you have more than three hours of weakness in the zonules, you will need several Irish hooks to maintain it. It just depends on the extent of the zonulopathy. Later you can insert a support ring and suture it to the sclera; Once that's done, take out the hooks.

Capsular tension rings and segments

Capsule clamping rings basically help with centering. So if you see that the capsular bag has shifted a bit, but the shift is only slight and the bag is not completely off-center, a CTR can solve the problem.

A few things to keep in mind:

•A CTR will not prevent postoperative subluxation.It helps with centering at the time of cataract surgery, particularly in patients with two or three hour zonulopathy, but it does not help prevent subsequent subluxation years later.

•A CTR will not prevent postoperative phimosis.Whatever the mechanism of capsular phimosis, CTR does not appear to counteract it. Therefore, it is important to do a good 5.5 mm capsulorhexis.

•When inserting the ring, avoid capsular laxity at the equator.Fill the capsular bag with cohesive viscoelastic. If it is not fully inflated when the ring is inserted, it can actually damage the zones.

•Use a second instrument when placing the CTR in the pouch.This can help you manipulate the ring without stressing the zones.

•Inject the CTR in the direction of zonular laxity.This will help avoid stress on the remaining zones.

Although CTR will not prevent a late subluxation or dislocation, my retinal peers tell me that if that IOL/capsule bag and CTR complex decides to dip onto the retina, the ring in the bag will help them find it again. You can just grab the edge and lift it up. The CTR keeps the capsular bag stretched almost 360 degrees, making it easier to grasp.

When zonal support is required for four or more hours during cataract surgery, one CTR is usually not sufficient. In this situation, a fixable capsule tension segment may be what you need. These segments have eyelets that allow them to be attached to the sclera. Often these segments only cover a few hours, as in the case of the Ahmed segment, but you can also use what is known as a modified Cionni ring, which is a CTR but with lugs. (You can also use several shorter segments to hold the capsule in place. If you place one segment and see the entire pouch tilt 180 degrees away from where you sew one eyelet, it makes sense to sew a second one at the opposite side.) Note that when inserting a segment, it is important to also insert a CTR in the pouch to stretch it evenly.

The benefit of using a sewable segment is that you can easily slip the segment into the pouch within the hours that the slack is present; The eyelet allows two-point fixation to the sclera with a CV 8-0 Gore-Tex suture. The eyelet is designed to be above the plane of the arch and protrudes superiorly and anteriorly outside the edge of the capsulorhexis so that it can be accessed while the CTR curved segment, covering approximately 120 degrees, sits in the capsular bag at the lens equator to keep it stretched. We simply make a small groove in the sclera, 1 or 1.5mm backwards, and pass the sutures through the groove. We bury the knot in the groove, so we don't have to make a flap.

This approach provides support where the zonules are absent, allowing the patient to have a well-centered IOL. (It also ensures the lens doesn't fall backwards later.)

Another thing to keep in mind: the size of the CTR is important. CTRs come in multiple sizes and sizing is critical to ensure the outward force generated by the ring is appropriate for the eye. Depending on the axial length of the eye, manufacturers give a recommendation on which CTR size to use.

In our practice we created a table and hung it on the wall. It gives us the recommended CTR size that is appropriate for the axial length of a given eye. So when I'm in this situation, I have my IOL printout and I ask the nurse, "What is the axial length for this eye?" (I will also confirm visually.) Then the CTR in the appropriate size from the reference table requested.

do what we can

Ironically, it is difficult to assess the effectiveness of each prevention strategy we employ, as clinical experience has shown that it can take an average of eight and a half years for dislocation or subluxation of the capsulorhexis-IOL complex to occur. This time lag makes it difficult to draw firm conclusions about the effectiveness of our efforts. Even so, it's easy to do things during surgery that can make the problem worse. Therefore, it is crucial for us to do everything in our power to identify a potential problem and take action to minimize the likelihood of postoperative complications.

dr Shareef is a professor at Case Western Reserve University/University Hospitals in Cleveland. He has no financial connections relevant to anything discussed in this article.