This article is from July/August 2010 and may contain outdated material.
For ophthalmologists, one of the most satisfying procedures of the profession is cataract surgery. The vast majority of cataract patients are pleased as their world shifts from cloudy to clear and in-focus. Yet every rose has its thorn, and, for cataract surgery, it is the situation warranting IOL explantation. Exchanging a lens is both frustrating and challenging, but there are several pearls that can help the process run smoothly.
Why Must This Lens Come Out?
David A. Goldman, MD, assistant professor of clinical ophthalmology at Bascom Palmer Eye Institute, said two mechanical issues can necessitate an explantation:
- Dislocation of a lens that was initially positioned correctly. This situation usually comprises patients with pseudoexfoliation and progressive weakening of the zonules, and those who experience trauma.
- Poor positioning of the lens in the first place. Malpositioned IOLs can result from capsular rupture during surgery, insufficient capsular support for sulcus fixation or a situation in which one haptic is in the capsular bag and the other is in the sulcus. On occasion, Dr. Goldman said, a surgeon may implant an anterior-chamber lens as quickly as possible to minimize patient discomfort. This may lead to incarceration of the iris or cause a malposition of the IOL. Malposition may also occur when a toric IOL rotates postoperatively, Dr. Goldman said. “All of these patients may prove to be candidates for explantation.”
Steven I. Rosenfeld, MD, in private practice in Delray Beach, Fla., and a voluntary professor of ophthalmology at the Bascom Palmer Eye Institute, said there are two other, more human, reasons why explantation would be considered:
- The power of the lens is evidently not correct, and the patient is still dependent on glasses.
- Lens power aside, the patient is not subjectively happy with the visual results.
The first of these two problems is easier to fix. “Patients with lens power issues have alternatives to explantation,” Dr. Rosenfeld said. “We can use a piggyback lens implant or do LASIK or PRK on the corneal surface to add or subtract power.” However, the fix is not so clear for patients who are subjectively unhappy with the quality of vision. While premium IOLs allow patients to experience good distance, medium and near vision, patient dissatisfaction is the Achilles’ heel of these advanced lenses. And the actual problem is often difficult to pinpoint. For example, they can read the eye chart very well yet have a hard time seeing in twilight, are experiencing reduced contrast sensitivity or complain of “Vaseline” vision. Such dissatisfactions are, unfortunately, surprises. “There is no way this outcome can be predicted in advance,” Dr. Rosenfeld said, “nor is there a way to substantiate a patient’s claim. However, prior to moving forward with explantation when a patient has vision quality issues, it is important to rule out irregular astigmatism, systemic dry eye, macular edema or macular epiretinal membrane.”
Dr. Rosenfeld noted that performing an explantation procedure is inherently more challenging than the original cataract operation. “You are opening the eye again, and you don’t know how firmly entrenched the lens is or if the capsular bag is fully intact.”
Five Pearls on Explantation
Those scenarios lead Parag A. Majmudar, MD, to his number one pearl:
1. Proceed with deliberation. “Do whatever you can to avoid an explantation. To clarify: When implanting premium lenses, always make sure the lens matches both the patients’ vision needs and their personalities. Don’t just pick a lens willy-nilly and hope it works. Always invest the chair time to explain to patients exactly what they can expect.
Dr. Majmudar, who is an associate professor of ophthalmology at Rush University in Chicago, also stressed the importance of being familiar with the nuances of each lens. For example, an informal survey at last April’s meeting of the American Society of Cataract and Refractive Surgery showed that 40 percent of the surgeons attending would still place a single-piece acrylic lens in the sulcus even though this practice is associated with complications that require explantation.
Dr. Majmudar said that surgeons should also remember that the brains of older patients are not as plastic as younger patients, which could have an impact on how well they adapt to presbyopia-correcting lenses.
2. Verify the problem. Dr. Goldman added another pearl: That patients dissatisfied with the quality of vision in presbyopia-correcting lenses should undergo an examination that includes OCT and corneal topography. “I had a patient come in dissatisfied with multifocal IOLs,” he noted. “He had a history of LASIK, and topography showed irregular astigmatism. When we fit him with an RGP lens he was able to see distance and read comfortably. Had we exchanged the lens, he very well may still have needed to wear the RGP lens. Thus, several of these patients may be better off with a contact lens to enhance the quality of vision rather than undergoing a lens explantation.”
3. Don’t wait (except on capsulotomies). Dr. Majmudar offers this advice: If a lens must be explanted, the earlier it’s done, the better. “The longer you wait to explant, the more likely there will be fibrosis in the capsular bag, which makes explantation much more challenging,” said Dr. Majmudar.
Dr. Rosenfeld agreed. “If patients are unhappy with their quality of vision, it is better to go in at one or two months rather than waiting for eight or 10 months. The longer the lens sits in the capsular bag, the greater the chances the two leaves of the capsular bag can adhere or scar.”
Dr. Rosenfeld also offered a complementary piece of advice: If there is any chance that a surgeon may have to exchange a lens implant, delay doing a YAG laser posterior capsulotomy. “Some cataract surgeons are quick to do a YAG laser procedure to remove opacification, but once you create an opening in the posterior capsule, it becomes much more difficult and dangerous to exchange the lens.”
4. Vitrectomize if needed. Dr. Rosenfeld offers this pearl: Note the possibility that the surgeon may need to do a vitrectomy. “Surgeons should be prepared to deal with the vitreous because it is quite possible that they may end up tearing the posterior capsule, or an existing tear could become larger,” Dr. Rosenfeld said.
Dr. Goldman added that, generally speaking, when explanting the lens, “surgeons shouldn’t be afraid to use as much viscoelastic as they need.” His technique involves using a 27-gauge needle attached to a viscoelastic, and using the sharp end to get under the edge of the anterior capsule. He then injects the viscoelastic to free the anterior capsule from the lens and then removes the lens. He then places a new one in the sulcus.
Dr. Majmudar also advocated viscoelastic (specifically VisCoat) in order to provide good support for the capsular bag and to give the surgeon a lot of space to work. “It helps stabilize the eye when removing the implant.”
5. Handle the haptics. Finally, Dr. Goldman said for explantations he prefers to use the MST anterior segment instrumentation (Microsurgical Technologies) that includes micrograspers and microtying forceps. The micro instruments allow Dr. Goldman to stabilize the IOL while cutting it, then dialing it out of the incision. “If necessary, I don’t hesitate to cut the haptics and leave them in the bag,” Dr. Goldman said. Dr. Majmudar echoed that advice: “In many instances, the haptic is difficult to remove. If you can’t get the haptics dislodged, or if you risk ripping the capsular bag if you try to take them out, then you have little choice but to amputate them. This won’t cause problems; the haptics can be left in the capsular bag.”
Dr. Majmudar also uses the MST micro-anterior segment set. “I don’t like to bisect the lens in two pieces when I remove it because this risks loose pieces of lenses remaining in the eye,” Dr. Majmudar explained. “Instead, I like to cut the lens a little more than half way. This allows me to pull one section out, then rotate the lens so it can be removed from the incision. Everything comes out in one piece, not in fragments.”
One last question. If not exactly a pearl, one final point involves who should actually do the explantation. “If a surgeon is not exactly sure why the patient is experiencing vision problems, or if the patient appears particularly hostile, it is always better to encourage the patient to get a second opinion, which will either confirm your course of action or give the patients other options,” Dr. Rosenfeld said.
Dr. Goldman agreed. “The patient may have lost faith in the outcome so it doesn’t hurt to refer the patient to a colleague down the street, and then the colleague can send the patient back for follow-up. But if the referral surgeon feels comfortable doing the explantation, that works as well.”
The physicians interviewed report no related financial interests.