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Thinking of piggybacking AcrySof IOLs? Don’t, surgeon says
A tenacious opacifying membrane formed between some primary piggyback AcrySof lenses, and long-term hyperopic shift has also been observed in some cases.
---Interlenticular opacification is the name coined by Dr. Apple for the formation of an opacifying membrane between piggyback IOLs, as seen here in this pair of explanted lenses.
PHOTOGRAPH COURTESY OF DAVID J. APPLE, MD
SEATTLE — Unanticipated adverse effects have led a previously vocal advocate of piggyback AcrySof (Alcon Surgical, Fort Worth, U.S.A.) IOLs to urge surgeons to stop using the popular foldable lens in this way.
Opening his presentation here at the annual meeting of American Society of Cataract and Refractive Surgery (ASCRS) with a clip from the 1979 Steve Martin film The Jerk, Warner Robins, Ga., cataract specialist Johnny L. Gayton, MD, revised his earlier position on piggyback AcrySof IOLs.
In the film, a character attaches a finger grip to the bridge of a pair of spectacles to make them easier to handle. The invention becomes very popular, but a subsequent epidemic of convergent strabismus breaks out as users become fixated on the device. For Dr. Gayton, it was a farcical example of the kind of unintended consequence that sometimes follows innovation.
“I was the person who took a great implant, the AcrySof lens, and recommended that doctors use that implant for piggyback implantation, and we had great results for several years,” Dr. Gayton said.
“It is still a great implant,” he emphasized. In fact, Dr. Gayton is himself a bilateral AcrySof pseudophake following cataract surgery.
“Unfortunately,” he told the ASCRS audience, “there are now problems with piggybacking and we are seeing, for want of a better term, interlenticular opacification [ILO],” a term proposed by David J. Apple, MD, who analyzed two of Dr. Gayton’s explants.
It is still safe to piggyback PMMA and silicone lenses he said, but due to the potential complications, two AcrySof lenses never should be piggybacked.
Two explants
After noting the first case of ILO, Dr. Gayton re-examined 32 of his patients with piggyback IOLs that had been in place at least 2 years. Nineteen eyes had piggyback AcrySof lenses, 11 had piggyback PMMA lenses and, two eyes had an AcrySof/PMMA combination.
Following the examinations, Dr. Gayton said two cases with piggyback AcrySof IOLs were found to have ILO sufficient to justify lens exchange.
“I had a hard time getting the lenses in one case to separate,” he said. “I thought I could aspirate the membrane from between the two implants, and lo and behold, it didn’t work. I ended up taking viscoelastic and injecting it between the IOLs.”
In one case the lenses could not be separated, so Dr. Gayton explanted them as a unit. In the other case, the viscoelastic injection did separate the lenses.
“I then tried doing irrigation and aspiration, trying to get the material removed,” he said, “but there was still significant membrane attached to the implants that would not come out.”
Five additional eyes of four patients were diagnosed with ILO. Four were primary double AcrySof implants, and one was a primary double PMMA implant.
“The primary double PMMA case was unusual because this was a phacomorphic glaucoma case with iritis,” he explained. “The membrane was probably unrelated to the piggyback implantation, and the membrane was easily stripped. In these other cases, however, that was not our good fortune.”
Hyperopic shift
Dr. Gayton noted another potential problem in the course of examining these patients. In the case where he was able to separate the lenses before removing them, he noticed a depression where the lenses had been bound by the membrane. This depression had altered the patient’s refraction.
Alteration of lens power was at first attributed to the membrane formation between the optic surfaces, but Dr. Gayton said refractive shifts were also identified in patients without ILO.
“One of our patients without a membrane between the two lenses experienced a hyperopic shift of 4 D in a little over a 2-year period,” he said. “The membrane formation can shift the position of the IOLs, but more importantly, the two implants pressing together is causing a depression in the optic that is actually altering the lens power.”
Pathological analysis
The explanted IOLs and membranes were sent to the laboratories of Dr. Apple at the Center for Research in Ocular Therapeutics and Biodevices of the Storm Eye Institute at the Medical University of South Carolina, Charleston. Pathological analysis by Dr. Apple and two colleagues, Drs. Qun Peng and Nithi Visessook, revealed that the ILO membrane was identical to the material seen in conventional PCO.
In both cases, “the content of the membrane was cortex and pearls,” Dr. Gayton said. Histopathological analysis showed that there was minimal pseudofibrous metaplasia, and very slight calcification. Epithelial cells were clearly visible on the anterior surface of the posterior lens and on the posterior surface of the anterior lens. Such cellular growth can usually be stripped from IOL surfaces, but the nature of acrylic makes membrane removal very difficult.
“I can assure you that these epithelial cells will not come off by just rubbing, scraping or aspirating,” Dr. Gayton said.
Dr. Apple later discussed the issue in his own presentation on PCO prevention during the opening session of the ASCRS meeting. Until researchers fully understand the cause of ILO, he said, the piggyback complication might be decreased with thorough cortical clean-up.
“That is really the key to making this work,” he said.
Cause a mystery
The etiology of ILO membrane formation is unknown, but Dr. Gayton said he is sure it is not a typical fibrotic reaction and indeed this correlated with Dr. Apple’s pathological findings.
“As a result of the discovery of ILO and as a result of the difficulty of handling this problem, I am suggesting that we go back to using PMMA lenses for piggyback systems,” he said. “Some of the higher index silicone might also be appropriate, but I certainly am not going to be recommending that we use this otherwise excellent lens for piggybacks in the future.”
A panelist presiding over the session in which Dr. Gayton presented his findings reported seeing the same phenomenon. Richard B. Packard, FRCS, noted that in one of his patients who had bilateral piggyback AcrySof IOLs, ILO appeared in only one eye, while the other eye remained completely clear. Dr. Packard asked Dr. Gayton if he thought the depth in the capsular bag created when the two lenses are placed in the bag together allows epithelialization to affect the IOLs.
Dr. Gayton said he was not sure, but noted that in both of his explant cases, the edge of the capsulorrhexis had covered the optic.
“If you had a large capsulorrhexis and it was adherent, that might prevent ILO, but I really don’t know,” he said. “We have about 120 piggyback AcrySof cases, and we will be looking at all of them to try to identify any problems. If those cases with a large capsulorrhexis do not develop this problem, than we will be better able to answer that question.”
Only in primary cases?
An audience member suggested that ILO may be limited to cases in which both acrylic lenses are in the bag. Nobody in the ASCRS session was aware of any case of ILO in secondary piggyback implantation in which the second lens had been placed in the sulcus.
Many secondary piggybacks have paired acrylic IOLs with PMMA IOLs, Dr. Gayton said, and none of these cases have been linked to ILO. In his practice, AcrySof lenses have been paired with PMMA, silicone, another AcrySof and even a MemoryLens.
“There have been no reported problems in secondary piggyback implants,” he said. “This appears to be a primary implant problem, and indeed it might be related to both IOLs being in the bag. The fact is, we are just really not sure. And frankly, I’m not going to take any chances.”
For Your Information:
- Johnny L. Gayton, MD, can be reached at P.O. Box 6479, Warner Robins, GA 31095-6479 U.S.A.; +(001) 912-929-6272; fax: +(001) 912-929-6266.
- David J. Apple, MD, can be reached at the Department of Ophthalmology/MUSC, Storm Eye Institute, 167 Ashley Ave., Charleston, SC 29425-2236 U.S.A.; +(001) 843-792-2760; fax: +(001) 843-792-7920; e-mail: appledj@musc.edu. Dr. Apple has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any of the companies mentioned.
- Richard B. Packard, FRCS, can be reached at Princess Christians Hospital, 12 Clarence Road, Windsor, SL4 5AG, England; +(44) 1753-829204; fax: +(44) 1753-831185.
- For more information on Alcon’s AcrySof IOL, contact David Eister at 6201 South Freeway, Fort Worth, TX 76134-2099 U.S.A.; +(001) 817-551-6828; fax: +(001) 817-241-0677.