April 2018

CATARACT

YES connect
Piggyback IOLs for the young eye surgeon


by Liz Hillman EyeWorld Staff Writer



Ultrasound biomicroscopy of a piggyback PCIOL in the sulcus
Source: Nicole Fram, MD



“The best thing young eye
surgeons can do when first
encountering this is ask for
advice from more experienced colleagues.”
—David Crandall, MD

In this month’s “YES connect” column, we explore the subject of piggyback IOLs. This refers to placement of a second IOL in front of the first IOL, with the second IOL either in the sulcus or in the bag. While we do not typically learn much about this topic in residency or fellowship, it may arise in the first several years of practice. When patients have residual refractive error after cataract surgery, several options exist: observation, glasses, contact lenses, laser vision correction, IOL exchange, and piggyback IOL placement. The techniques and instrumentation available for IOL exchange procedures have improved over the years, and frequently IOL exchange can be a more attractive option, but there are still situations when piggyback IOL placement is preferable. Piggyback IOLs can also be used to correct large refractive errors in eyes with unusual axial lengths or keratometry, when the refractive error cannot be entirely corrected by any available single IOL. Additionally, they may be useful for treatment of negative dysphotopsias. There are many considerations to ensure proper patient selection as well as safe and stable IOL placement. We asked David Crandall, MD, Nicole Fram, MD, Warren Hill, MD, Douglas Koch, MD, and Liliana Werner, MD, PhD, for advice.

Naveen Rao, MD,
YES connect co-editor


When to do one, lens choice, calculations, and more

Ophthalmologists are not typically trained in residency or fellowship about how and when to do a piggyback IOL. The reason for this could be multifactorial. According to Nicole Fram, MD, Advanced Vision Care, Los Angeles, (1) it might be assumed if the surgeon can put a three-piece lens in the sulcus, he or she should be able to put in a piggyback lens, and (2) with indications for a piggyback IOL narrowing, the need to implant them is rare.
David Crandall, MD, Henry Ford Eye Care Services, Detroit, said most residents, without realizing it, learn the surgical mechanics of placing a piggyback lens.
“I teach them that it is just like placing a sulcus lens, but they have the safety of a lens already in the eye between them and the vitreous, so it’s a more controlled situation than they are usually dealing with after a ruptured posterior capsule,” Dr. Crandall said. “The best thing young eye surgeons can do when first encountering this is ask for advice from more experienced colleagues; [ASCRS] EyeConnect is a great resource for this.”
Dr. Fram, who has a referral practice for unhappy cataract patients and thus, theoretically, would be more likely to see piggyback IOL candidates, said she only performed two such procedures within the last year. Douglas Koch, MD, professor and Allen, Mosbacher, and Law Chair in Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, said he has only performed one piggyback IOL within the last 3 or more years. “My concern is the risk of developing chronic iris chafing and uveitis, so I avoid piggyback IOLs whenever possible,” Dr. Koch said.
Dr. Koch and Warren Hill, MD, East Valley Ophthalmology, Mesa, Arizona, and member at large of the ASCRS Governing Board, said they prefer to do an IOL exchange rather than a piggyback.
“I generally do not implant piggyback IOLs,” Dr. Hill said. “Instead, I think exchanging the incorrect IOL for the correct one is the better option.”
There are cases, Dr. Hill acknowledged, when exchange might not be possible, such as when too much time has passed since the initial cataract surgery.
“There are many factors that go into whether or not to perform a piggyback lens,” Dr. Crandall said.
The first of those is whether it’s actually necessary. If the patient is comfortable and happy with glasses or contacts, there is no need for him or her to go through this procedure. The second is whether there is room for a second lens in the eye.
“If there is not, then that decision is made for us,” Dr. Crandall said. “Any other anterior chamber abnormalities will lead me away from doing this because they may already be at risk for glaucoma, and a mild UGH syndrome could push them over the ledge. If they have pseudophacodonesis or exfoliation syndrome, I think it is best avoided or you may risk having to exchange or reposition two lenses in the future.”
Overall, Dr. Crandall said if a significant refractive error is detected early, he prefers IOL exchange over a piggyback, performing the procedure a few weeks after initial cataract surgery. If the posterior capsule is intact, Dr. Crandall will also lean toward exchange, even if a longer time has passed after surgery.
Dr. Fram said the perfect piggyback IOL candidate would be a post-RK patient who is hyperopic and years out from surgery. Hyperopia is a common refractive outcome in these patients due to the instability of their corneas after RK and because IOL power formulas don’t do as well with targeting in post-RK patients. These patients also tend to have a deep chamber, which Dr. Fram said is nice when putting in a piggyback IOL. If the patient is 3 months post-cataract surgery and there’s a refractive miss, Dr. Fram will perform an IOL exchange, but if she’s seeing them 10 years later, then a piggyback can be an appropriate choice.
Dr. Fram also said a piggyback lens might be used if the patient has a hyperopic outcome and pseudoexfoliation or zonule issues, and you don’t want to reopen the bag or stress the zonule. This patient would need to have an appropriate anterior chamber depth and a “good solid sulcus,” Dr. Fram added. If a patient with these issues had a myopic refractive surprise, Dr. Fram would prefer to perform PRK or LASIK as a correction.
Piggyback IOLs have been successful in correcting negative dysphotopsias. Dr. Fram said she and Samuel Masket, MD, Los Angeles, have found piggyback IOLs to have a 73% success rate in reversing negative dysphotopsias, but reverse optic capture of the primary IOL was more effective with a success rate of more than 90%. The Sulcoflex (Rayner, West Sussex, U.K.), an acrylic sulcus-fixated IOL not available in the U.S., has been shown to reduce negative dysphotopsia as well, Dr. Fram noted.1
Dr. Fram and Dr. Crandall prefer reverse optic capture when possible in these cases.
In addition to choosing the right patient for this procedure, there are some other challenges. One is deciding which type of IOL to use. Two years ago, the STAAR AQ5010V (STAAR Surgical, Monrovia, California), a silicone lens popular as a piggyback IOL, was discontinued. This was unfortunate as it came in negative powers and was “sulcus friendly” due to the round edge and silicone material, Dr. Fram said. The LI61AO SofPort (Bausch + Lomb, Bridgewater, New Jersey) is a silicone lens, but it does not come in negative powers.
Dr. Crandall said he chooses the material of a piggyback lens based on what’s already in the eye. If there is an acrylic already placed, he will use a silicone piggyback. The LI61AO and Tecnis Z9002 (Johnson & Johnson Vision, Santa Ana, California) are reasonable options with easy availability, Dr. Crandall said. Without the STAAR AQ5010 available as a negative power silicone lens, Dr. Crandall leans toward an alternative treatment for residual myopia.
“I will usually prefer lens exchange or laser vision correction for necessary treatment. The negative power acrylic lenses tend to have very thick edges, so I have worries about iris chafing and UGH syndrome in the long run,” he said.
He will also opt to place piggyback lenses in the sulcus, finding it a safer and quicker option than reopening the bag.
There are several ways to go about calculating the power of a piggyback IOL, Dr. Hill said. These include the refractive vergence formula (available on Dr. Hill’s website, doctor-hill.com), the Holladay R formula, or the Barrett Rx formula (available on the Asia-Pacific Association of Cataract and Refractive Surgeons website).
“Because this type of calculation is based on the refractive error (and to a lesser degree the Ks), the accuracy is generally very good,” Dr. Hill said. “The main limitation, however, for lower power or minus power IOLs is that they typically come in 1.00 D steps, so an exact correction may not be possible with a piggyback IOL, unless the required power lines up with what’s available.”
Dr. Fram provided a shortcut calculation formula.
“A well-known shortcut is to take a myopic error and multiply 1.2 x the spherical equivalent of your refraction of the missed target. If it’s hyperopic, you multiply 1.5 x the spherical equivalent of the refraction. That works out well for most cases,” she said. The Barrett Rx formula is also useful, however, you need preoperative and postoperative measurements.
As for injection of the IOL, Dr. Fram said you have to understand how to pronate and supinate to make sure the haptic is going into the sulcus correctly. The LI61AO comes out planar, so you don’t have to worry about twisting your wrist to get the right conformation. Surgeons can practice inserting piggyback IOLs with SimulEYE (InsEYEt, Westlake Village, California) prior to live surgery. Dr. Fram said this allows surgeons to get the movements down and familiarize themselves with what’s going to happen intraoperatively.
Dr. Fram recommended the use of a dispersive ophthalmic viscoelastic device (OVD) to protect the cornea and a cohesive to give yourself room to manipulate in the eye; this is where an adaptive OVD could be handy. In addition, intracameral miotics are useful to bring the pupil down after the insertion of the piggyback IOL.
Complications to be aware of include pupillary capture. You’ll want to use acetylcholine chloride and/or carbachol to bring the pupil down and prevent this, Dr. Fram said. Other postoperative issues include pigment dispersion, secondary glaucoma, iris transillumination defects, and intermittent iritis, Dr. Hill said.
There is also the issue of interlenticular opacification to be aware of. This, Liliana Werner, MD, PhD, professor of ophthalmology and visual sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, who has researched the topic extensively, said seems to occur when two posterior chamber hydrophobic acrylic IOLs are implanted in the capsular bag through a small capsulorhexis with the margins overlapping the optic edge of the anterior IOL.2 She pointed out that all of the explanted lenses with this issue that were sent to the Intermountain Ocular Research Center for analysis were three-piece AcrySof IOLs (Alcon, Fort Worth, Texas). Dr. Werner said the adhesive nature of the hydrophobic acrylic material may have contributed to this complication. Its pathogenesis is likely similar to that of posterior capsule opacification, derived from retained/regenerative cortex and pearls, Dr. Werner said.
Surgical methods to prevent interlenticular opacification include implanting both IOLs in the capsular bag with a capsulorhexis that’s larger in diameter, but Dr. Werner acknowledged that the implantation of two hydrophobic acrylic IOLs in this case should be avoided; and implanting the secondary IOL in the sulcus with the primary IOL in the bag with the traditional small capsulorhexis. Sulcus-placed IOLs should have sufficient posterior iris clearance (obtained with posterior optic/haptic angulation) with a smooth anterior optic surface, a rounded anterior optic edge, and an overall IOL diameter of at least 13.0 mm for centration and stable fixation, Dr. Werner said.3–5 IOLs specially designed to be used as piggyback (supplementary) IOLs for sulcus fixation are available in some markets.6–8
Overall, Dr. Fram said piggyback IOLs are within the skillset of young ophthalmologists. Surgeons need to understand the criteria for patient selection; that they’ll be limited in the IOLs available for use; how to put in a three-piece lens in the sulcus; and the signs of pigment dispersion or iris chafing that might merit the secondary lens being removed.
“I think the critical point is understanding the appropriate clinical indications—it’s these hyperopic outcomes with deep chambers and healthy sulcus—and understanding the postoperative signs of UGH or pigment dispersion. Chronic pigment in the angle can lead to irreversible damage and can be avoided with close observation,” Dr. Fram said.

References

1. Makhotkina NY, et al. Treatment of negative dysphotopsia with supplementary implantation of a sulcus-fixated intraocular lens. Graefes Arch Clin Exp Ophthalmol. 2015;253:973–7.
2. Werner L, et at. Interlenticular opacification: dual-optic versus piggyback intraocular lenses. J Cataract Refract Surg. 2006;32:656–61.
3. Chang WH, et al. Pigmentary dispersion syndrome with a secondary piggyback 3-piece hydrophobic acrylic lens. Case report with clinicopathological correlation. J Cataract Refract Surg. 2007;33:1106–9.
4. Kirk KR, et al. Pathologic assessment of complications with asymmetric or sulcus fixation of square-edged hydrophobic acrylic intraocular lenses. Ophthalmology. 2012;119:907–13.
5. Ollerton A, et al. Pathologic comparison of asymmetric or sulcus fixation of 3-piece intraocular lenses with square versus round anterior optic edges. Ophthalmology. 2013;120:1580–7.
6. McIntyre JS, et al. Assessment of a single- piece hydrophilic acrylic IOL for piggyback sulcus fixation in pseudophakic cadaver eyes. J Cataract Refract Surg. 2012;38:155–62. 
7. Reiter N, et al. Assessment of a new hydrophilic acrylic supplementary IOL for sulcus fixation in pseudophakic cadaver eyes. Eye (Lond). 2017;31:802–809. 
8. Tsaousis KT, et al. Assessment of a novel pinhole supplementary implant for sulcus fixation in pseudophakic cadaver eyes. Eye (Lond). 2018;32:637–645.

Editors’ note: The physicians have no financial interests related to their comments.

Contact information

Crandall: dackakarot@hotmail.com
Fram: nicfram@yahoo.com
Hill: hill@doctor-hill.com
Koch: dkoch@bcm.edu
Werner: Liliana.Werner@hsc.utah.edu

Piggyback IOLs for the young eye surgeon Piggyback IOLs for the young eye surgeon
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