Foldable IOLs have helped alter the face of cataract surgery by improving healing time, limiting complications and making phacoemulsification the standard procedure over extracapsular surgery, all in the span of 2 decades.
At first, the new lenses and procedures were not widely accepted at their advent in the mid-1980s, physicians said. PMMA IOLs were the standard IOLs used at that time, and they were typically inserted through 5-mm to 7-mm incisions after extracapsular surgery. More than 20 years later, most surgeons now implant foldable acrylic or silicone IOLs after phaco, and PMMA lenses are used only in special cases.
Richard L. Lindstrom, MD, Chief Medical Editor of Ocular Surgery News, estimated that about 90% of the lenses implanted in the United States are foldable acrylic or silicone lenses and that the dominant lenses are one-piece or three-piece modified C-loop lens implants. Phacoemulsification is performed in about 95% of cataract removals, he said.
The main advantages of the foldable IOL are the smaller incision size – 3 mm or smaller – and faster wound healing time, Dr. Lindstrom said. Several companies have produced their own versions of the lens, from silicone versions to the later development of acrylic IOLs.
Richard L. Lindstrom
William F. Maloney, MD, OSN Cataract Surgery Section Editor, called the introduction of foldable IOLs a “critical milestone” in the 50-year evolution of cataract surgery. This introduction suddenly made phacoemulsification no longer optional, but an essential element of small-incision cataract surgery that greatly improved surgical results.
“We will probably never see a period like that again in our specialty or, dare I say, almost any medical specialty,” Dr. Maloney said. “The development of refractive cataract sugery has created an unprecedented golden era.”
History of foldable IOLs
In 1949, Sir Harold Ridley implanted the first cataract IOL at Saint Thomas’ Hospital in London. The beginnings of the technology that would ultimately result in the creation of the foldable IOL can be traced back to Dr. Ridley’s surgical innovations, surgeons say.
The next important development in the history of foldable IOLs was in 1967, when Charles D. Kelman, MD, introduced the phacoemulsification procedure. Phaco allowed for smaller incisions, but it was not widely used at the time because after the smaller incisions were created, larger incisions had to be made to insert the rigid PMMA IOLs.
Then, in the early 1980s, Thomas R. Mazzocco, MD, developed what became known as the “Mazzocco taco,” a silicone foldable IOL.
Edward Epstein, MD, in Johannesburg, South Africa, had been working with soft implants for some time. Dr. Mazzocco developed the soft implant technology into a foldable IOL. His plate haptic IOL was folded length-wise like a taco. Working with STAAR Surgical, which he co-founded, Dr. Mazzocco developed the foldable, autoclavable lens.
“I developed the folding implant lens to take advantage of the small incision cataract surgery of Dr. Charles Kelman, to avoid enlarging the incision and to allow safe sutureless surgery,” Dr. Mazzocco, who is now retired from ophthalmology, told OSN by e-mail.
“I would presume that the folding lens has allowed the small incision cataract surgery to proliferate, has allowed the implantable phakic lens to develop and has allowed an entire ‘lens replacement’ field of surgery to develop,” Dr. Mazzocco said.
The most innovative part of the lens was that its design allowed for insertion through a 3-mm incision. Phaco could now be performed with a keratome incision, and instead of enlarging the wound for IOL insertion, the folded IOL was inserted with forceps and unrolled in the eye. Later, a manual folder or injectors were used to insert the lens, helping to reduce the risk of endophthalmitis via a cleaner insertion process.
Dr. Maloney said he was doing a fellowship with Richard Kratz, MD, and Dr. Mazzocco in the early 1980s to learn phaco, which the two doctors were performing regularly. One day, Dr. Mazzocco was performing a routine phaco case, Dr. Maloney said, but the eye did not need a lens implant and required only a 3-mm incision. After observing the patient’s quick recovery time and lack of complications, Dr. Mazzocco was inspired to investigate ways to create a lens for smaller incision surgery, Dr. Maloney said.
Impact of foldable IOLs
John D. Hunkeler, MD, said he was “enamored” of Dr. Mazzocco’s innovation when he first heard about it in the mid-1980s. He took part in a clinical trial with American Medical Optics (now Advanced Medical Optics) in 1986 with a foldable lens. He said he was impressed with both the visual and functional results of the foldable technology. Since then, he has inserted foldable lenses exclusively.
He said he questions if other major changes in ophthalmic surgery would have been possible had foldable IOLs not been invented and phaco not become popular. He said eye surgeons might still be doing radial keratotomy rather than laser refractive surgery.
“They might not be doing this highly mechanized technology that we use with LASIK or IntraLase,” Dr. Hunkeler said. “I don’t know how well that would be accepted today, had we not gone through the phase of learning about the advantages of phaco and foldable technology. I don’t think some of the things we have today would be here were it not for the rapid embrace of not only ophthalmologists in the U.S., but internationally, of these technologies.”
I. Howard Fine, MD, OSN Cataract Surgery Section Member, called foldable IOLs and the wider use of phaco the “seminal” innovation in cataract and refractive surgery. Patients now recover faster, do not require a hospital stay and have surgery on an outpatient basis, he said.
“The foldable IOL converted everybody to phaco, allowed patients to have immediate recovery of vision and has lent itself to the development of refractive lens exchange as a major modality in refractive surgery,” Dr. Fine said. “It dramatically changed the whole nature of cataract surgery, and that has allowed us to do refractive lens exchange because we can do these extractions of the lens with phaco equipment through a very small incision and then implant a multifocal or accommodative IOL.”
He said the clear corneal incisions from the temporal periphery allowed for more stable astigmatism management. With extracapsular surgery before foldable IOLs, surgically induced astigmatism caused a wait of 2 to 3 months before spectacles could be prescribed, he said, but the smaller incisions did not create astigmatism. This surgically induced astigmatism had been a serious issue for patients because it could result in a delay of uncorrected vision and a fluctuation of cylinder axis and power for more than 5 years, Dr. Fine said.
Dr. Lindstrom said the lack of surgically induced astigmatism most likely helped move presbyopia- correcting technology forward.
“In the modern day of multifocal and accommodating IOLs, without quality of astigmatism management, we cannot really achieve high-quality no-glasses uncorrected vision,” he said.
Dr. Lindstrom said foldable IOLs also paved the way for the development of minimally invasive surgery. It can be performed under topical anesthesia and allows for a sutureless incision, resulting in rapid visual rehabilitation. It also potentially reduces the risk of wound leaks and secondary infection with properly made incisions, he said.
Impact on phaco
The advent of the foldable IOL brought phaco to the forefront of surgical technologies because it enabled surgeons to take advantage of smaller incisions. According to Dr. Maloney, from the time that phaco was introduced in 1967 up to 1985, only 5% to 10% of surgeons used phaco.
From 1985 to 1995, a “dramatic phaco revolution” occurred, Dr. Maloney said. The less than 10% of surgeons using phaco in the early 1980s rocketed to 95% by 1995.
“In a remarkable 10-year period, phaco completely replaced a good ECCE procedure,” he said. “That revolution was catalyzed by the introduction of the foldable lens because no longer did you need to enlarge the 3-mm phaco incision. The advantages of phaco and a bona fide small-incision procedure were fully realized.”
In the early 1980s, Dr. Maloney took part in the fellowship with Dr. Kratz and Dr. Mazzocco after Dr. Kratz presented on phaco at the Mayo Clinic, where Dr. Maloney was the chief resident. Dr. Maloney said he realized that phaco was the future of cataract surgery and that he should learn all he could about the technique before he entered his own practice.
“I sat there as a resident, just about to leave the Mayo Clinic and go into practice, and I realized that I was already outdated before I even started because this was obviously the future,” he said. “Dr. Kratz agreed to take me as a fellow, so I didn’t have the same steep learning curve as I would have, had I been out in practice for years and have to come back and completely relearn phaco.”
For many surgeons who did not know phaco and had been using extracapsular surgery for years, the sudden introduction of the foldable IOL and phaco was daunting. Dr. Maloney said he appreciated the difficulty that surgeons went through relearning and then regularly practicing phaco. He directed the largest phaco course ever presented that, over a 10-year period, taught thousands of ophthalmologists worldwide the “three steps to phaco.”
Dr. Hunkeler said he had to relearn phaco over the summer of 1986 to be ready to insert the folded AMO lens through the 3.5-mm incision after completion of phacoemulsification.
“That was the turning point for me to become virtually 100% phaco, and I made that change over the summer and the fall,” Dr. Hunkeler said. “Then we were allowed to start inserting the lens, folded. At that point, we had forceps to fold the lens, as opposed to disposable cartridges and devices to push the lens through the cartridge.”
He said the surgeons who switched to foldable lenses and phaco during that time saw a “tremendous practice growth” because of the increased benefits of smaller incisions.
Dr. Fine said some doctors did not initially embrace the technology. Eventually, the older methods of performing cataract surgery were rendered out of date because of fast-moving improvements, he said.
“Once foldable lenses came, extracapsular surgeons started to lose market share, and they either had to retire or convert to phacoemulsification because extracapsular surgery couldn’t compare to phacoemulsification with the implantation of a foldable IOL,” Dr. Fine said.
Future of technology
After the foldable lens was introduced, the next 20 years were spent refining the spherical and astigmatic elements of refractive cataract surgery, according to Dr. Maloney. That has led to a procedure that accurately corrects existing refractive error.
Now, surgeons are examining the lenses in regards to presbyopia correction, he said. He said the future of the lens might bring smaller, easier injectors and possibly the delivery of the IOL from a preloaded injector.
Dr. Lindstrom said companies are developing foldable, injectable lenses that can be implanted through 1.5-mm and 2-mm incisions. He said the trend continues toward injectable lenses and smaller incisions in cataract surgery. Lenses that could be inserted through a 1-mm or smaller incision could be about 10 years away, he said.
“The journey is still going on,” Dr. Lindstrom said.
For more information:
- I. Howard Fine, MD, is a clinical professor of ophthalmology at the Casey Eye Institute at Oregon Health & Science University in Portland. He can be reached at 1550 Oak St., Suite 5, Eugene, OR, 97401; 541-687-2110; fax: 541-484-3883.
- John D. Hunkeler, MD, is a clinical professor at the University of Kansas School of Medicine in Kansas City. He can be reached at 7950 College Blvd., Overland Park, KS 66210; 913-338-4733.
- Richard L. Lindstrom, MD, is the Chief Medical Editor of Ocular Surgery News. He is in private practice at Minnesota Eye Consultants, 710 E. 24th St., Suite 106, Minneapolis, MN 55404-3810; 612-813-3600; fax: 612-813-3660.
- William F. Maloney, MD, is head of Maloney Eye Center of Vista. He can be reached at 2023 West Vista Way, Suite A, Vista, CA 92083; e-mail: firstname.lastname@example.org.
- Thomas R. Mazzocco, MD, can be reached at email@example.com.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.