March 2011

 

CATARACT/ IOL

 

Dealing with zonular dehiscence


by Brock K. Bakewell, M.D.
 

Adjunctive surgical devices, such as dyes, pupil expansion rings, and capsular rings and hooks, have added to the safety and efficacy of modern cataract surgery. Cases that were once extremely difficult and challenging can now be addressed routinely with the use of these tools. In this month's column, Brock Bakewell, M.D., reviews some of the issues regarding the use of capsular tension rings in the presence of zonular weakness or dehiscence. I found his insertion technique for the single-loop Cionni ring to be particularly valuable and look forward to trying it on my next ectopia lentis case. I hope you will find his review and discussion helpful for your next case with loss of zonular integrity.

Richard Hoffman, M.D. Column Editor

 

Brock K. Bakewell, M.D., clinical assistant professor of ophthalmology, University of Utah, Salt Lake City, discusses what to do when encountering loose zonules

Cionni one-loop CTR being inserted Source: Brock K. Bakewell, M.D.

Cionni one-loop CTR in the eye Source: Brock K. Bakewell, M.D.

Surgeons may not be able to prevent zonular dehiscence from occurring, but if it is anticipated early and dealt with properly, they can save themselves the trouble of dealing with a decentered or dislocated posterior chamber IOL in the future. Otherwise, additional surgery will be necessary to suture fixate the PC IOL. Therefore, if there is any zonular dehiscence at the time of cataract surgery, a capsular tension ring (CTR) should be placed in the capsular bag.

One of the most common causes of zonular dehiscence is pseudoexfoliation. Extraocular trauma and surgical trauma are also frequent causes. In addition, zonular dehiscence can be brought on by genetic or congenital disorders such as Marfan syndrome.

Certain patients are already set up for zonular dehiscence. For example, if pseudoexfoliation is observed upon examining the patient prior to cataract surgery, there should be a higher index of suspicion that zonular problems may occur. If the patient has had a retinal detachment and silicone oil was used to fix the detachment, the silicone oil can certainly cause zonular dehiscence as well. When performing the pre-op slit lamp exam, surgeons must pay attention to whether the lens jiggles at all when the patient is instructed to move his or her eye back and forth. If the lens jiggles, that means the patient has loose zonules and there is phacodonesis. Patients who have pre-op phacodonesis need a CTR.

Often, however, surgeons may not discover phacodonesis until they are intraoperative. It may not be until they are removing some of the cortex that they notice it. They may pull out cortical lens material and then find that the bag is very loose in that certain meridian. Therefore, whenever I detect any weakness of the capsular bag I will go ahead and put a CTR in. Zonular dehiscence can even happen prior to a cataract. If a patient has Marfan syndrome, the lens can become dislocated in the eye. The patient may have significant problems seeing because of a refractive error that cannot be corrected by glasses or contacts. In this case, the patient might need to have a lens removal, even though he or she doesn't have a cataract, because of the dislocated lens. The techniques and tools for dealing with zonular dehiscence depend on how serious the problem is. The standard CTR is not meant to be suture fixated.It is placed in the capsular bag for zonular dehiscence up to 3 or 4 clock hours.However, some patients can have loss of a significant number of zonules. If there is significant zonular dehiscence, greater than 3 to 4 clock hours, a Cionni CTR should be used because this is designed for scleral suture fixation in order to secure the capsular bag. When using a one-loop Cionni CTR, my preferred method of insertion is an injector.When using an injector, it is not possible to completely retract the one-loop Cionni.It can only be retracted up to the loop, so two-thirds to three-fourths of the ring can be retracted into the injector.I prefer this to manual insertion since the injector requires only one hand, which frees up the other hand for manipulating the leading eyelet of the ring with a Sinskey hook.I use the Sinskey hook to engage the leading eyelet of the ring while I am injecting the Cionni CTR.This allows the CTR to be bent so that it doesn't engage a loose capsular bag and cause more zonular damage. Once more than half of the CTR is in the eye, the Sinskey hook can be removed to release the leading loop into the bag.Then the plunger in the injector is completely extended to release the trailing loop into the bag.Sometimes it is easier to release the trailing loop first, followed by the leading loop.For a surgeon who wants to inject with his right hand, Cionni type 1L (Morcher, Stuttgart, Germany) rings should be purchased.For a surgeon who wants to inject with his left hand, Cionni type 2C (Morcher) rings should be obtained. The 1L is injected counterclockwise in the capsular bag with the surgeon's right hand.The 2C is a one-loop Cionni that is injected clockwise with the surgeon's left hand.

Always monitor the Cionni loop during insertion to make sure that it stays anterior to the anterior capsule and doesn't get placed in the bag.When suturing, it is very important that the surgeon uses the 9-0 prolene, not the 10-0, because the 9-0 will not degrade in the eye over time like a 10-0 will. Don't over tighten the 9-0 prolene suture to the sclera because this can decenter the entire capsular bag and IOL. Create a Hoffman scleral pocket in order to bury the 9-0 prolene knot. Richard S. Hoffman, M.D., clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, came up with the idea to create an incision on the cornea so the surgeon can tunnel back into the sclera to create a pocket so that the CTR can be sutured under the sclera without dissecting the conjunctiva. It's a very good way to secure the Cionni CTR as well as the Ahmed capsular tension segment (CTS). I really like the Hoffman scleral pocket and I use that all the time. If a surgeon has already placed a standard CTR and the capsular bag is still decentered, an Ahmed CTS may be placed and suture fixated to the sclera to better center the capsular bag.

Great devices that aren't used enough

The devices mentioned are some of the wonderful tools that surgeons probably aren't using enough. The long-term effectiveness of CTRs has been excellent and that's why the FDA finally approved the basic model in 2003, 10 years after the CTR was originally designed.

I recently had a patient who had a retinal detachment, which was dealt with using silicone oil, causing about 6 clock hours of zonular dehiscence. However, I was able to take the cataract out, put a one-loop Cionni CTR in, and suture it to the sclera. Surgeons should bear in mind that this can't be done in a 15-20 minute case; the procedure does take extra time. I usually schedule these at the end of the day so I can spend all the time I want on them. The patient mentioned now has the lens implant in a very appropriate position in the eye so it was worth the extra effort.

Editors' note: Dr. Bakewell has no financial interests related to this article.

Contact information

Bakewell: 520-293-6740, EyemanAZ@aol.com

Dealing with zonular dehiscence Dealing with zonular dehiscence
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