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Secondary piggyback IOL can help refine refractive outcome of cataract surgery
The technique may help surgeons meet patient expectations for refractive outcomes following cataract surgery.
 A silicone IOL is injected into the sulcus over an already implanted IOL. Images: Masket S |
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More surgeons should embrace the “piggyback” IOL technique to enhance the refractive outcome of cataract surgery, according to Samuel Masket, MD, an anterior segment surgeon in private practice in Los Angeles.
“The piggyback IOL is an underutilized technique that works extremely well in my hands,” Dr. Masket said at the annual meeting of the American Society of Cataract and Refractive Surgery in San Diego. “I have had only excellent results in approximately 30 cases of secondary implant over the past 5 to 6 years. It is not a difficult procedure. It is clearly within the realm of any cataract surgeon.”
‘Original sin’
Dr. Masket said Johnny L. Gayton, MD, and James Gills, MD, first introduced the concept of more than one lens inside the eye for high ametropia. “But this technique has also been used for patients who have undesired optical results from surgery,” Dr. Masket said. “A wrong-powered IOL still constitutes the No. 1 reason for explantation. Why does this occur? It is due to the ‘original sin’ of all IOL formulas. They all assume the final resting place of the lens, which, of course, is impossible to know preoperatively,” he said.
According to Dr. Masket, there are several variables that can cause IOL power calculations to fail, including post-refractive surgery corneal curvature. “This still remains an enigma for many of us,” he said. “But we can also measure the refractive error intraoperatively. There are a number of post-surgical options. However, the concept that makes most sense to me is a secondary piggyback or secondary polypseudophakia.”
Dr. Masket noted that IOL exchange is more traumatic than adding an IOL, and the cost of “bioptics” – combining refractive corneal surgery with IOL implantation – is higher. One must also wait 2 or 3 months after cataract surgery to perform LASIK, LASEK, PRK, conductive keratoplasty or even incisional surgery. “An IOL exchange can also be done, but it is a bit more risky, and if you are unsure as to why you did not achieve a desired outcome with the original lens, a new lens may not be the answer,” Dr. Masket said. “It is always better, in my view, to deal with the error that you know exists.”
A secondary piggyback lens corrects the amount of error directly and may be a reimbursable procedure, he said.
The IOL’s proximal haptic is manipulated into the ciliary sulcus. | ||
Surgical considerations
“The first IOL must be totally confined to the capsular bag. The zonules must also be intact and strong,” Dr. Masket said. The secondary lens is placed in the ciliary sulcus, not in the capsular bag, because of concern about interlenticular opacification. “The optic edge should be rounded, at least, on the front edge and the loop angulated 10° to prevent postoperative capture of the pupil,” Dr. Masket said. “I bring the pupil down intraoperatively and do not dilate the patient in the early postoperative period.”
Surgeons should avoid using a secondary lens with an anterior square edge, Dr. Masket said. “This type of lens may promote posterior iris chafing syndrome,” he said. “Of course, our surgery must be gentle, so as not to disturb the condition of the existing zonules.”
Dr. Masket said he strongly prefers a silicone lens in the ciliary sulcus because there is less surface friction than an acrylic lens. “I think silicone is the best material for the optic,” he said. “The AcrySof lens (Alcon), in particular, has a surface that tends to be tacky. This can irritate or cause pigment dispersion in the posterior iris.”
Dr. Masket also said the optic size of the secondary lens should be at least 6 mm, and the overall loop length a minimum of 13.5 mm. “This allows wiggle room in the ciliary sulcus,” he said. The loop material should also be well tolerated by the posterior iris surface.
Lens recommendations
The STAAR 5010 lens for high myopia was previously Dr. Masket’s lens of choice for piggybacking. “But we now also have a wider power availability, from –10 D to +30 D with the AMO Clariflex in 0.5-D steps.” To calculate refraction for a hyperopic error, multiply the spectacle error by 1.5, he said. For myopic error, multiply by 1.1.
“Any technology imaginable can be used for a secondary piggyback implant,” Dr. Masket said. “We can use low-power pseudoaccommodating lenses, and, theoretically, with adjustability of lenses we can use wavefront analysis to establish custom vision for any patient. Furthermore, if it turns out that adding a chromophore is beneficial, we can then place a piggyback on top for macular protection. We can use toric correction and, of course, help in aniridic situations.”
Dr. Masket noted there is a lot of interest in a yellow-tinted lens. “If studies indicate that a yellow lens protects the macula, we could implant that lens in any number of patients who presently have a clear IOL. Secondary lenses can also be considered to correct iris defects,” he said.
For Your Information:
- Samuel Masket, MD, can be reached at 2080 Century Park East, Suite 911, Los Angeles, CA 90067; 310-229-1220; fax: 310-229-1222; e-mail: avcweb@aol.com. Dr. Masket is a paid consultant for Advanced Medical Optics.
- OSN Correspondent Bob Kronemyer is based in Elkhart, Indiana.