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New devices offer potential of perfectly sized, shaped and centered CCC
Extracapsular cataract extraction was pioneered by Jacques Daviel in 1747. Even in those pioneering years, an anterior capsulotomy was required. In these early cases, the anterior capsule was torn open with a sharp instrument, the first cystotome. Albrecht von Graefe, in 1850, just over 100 years later, refined creation of the anterior capsular opening to a capsulectomy, using forceps to lacerate and remove a portion of the anterior capsule. In 1917, Ignacio Barraquer led ophthalmic surgeons away from extracapsular cataract extraction to intracapsular cataract extraction, and ICCE dominated over ECCE until the 1980s. It is interesting and amazingly insightful that Sir Harold Ridley chose ECCE and a posterior chamber location for the very first IOL implant surgery he performed at St. Thomas’ Hospital in London on Nov. 29, 1947. Nov. 29 is my birthday, and I was exactly 2 years old when the first ECCE with a posterior chamber lens was performed.
Many surgeons tried to make ICCE with iris-supported and anterior chamber IOLs work well, but IOL fixation was poor, lens implant sequestration from metabolically active tissues absent, and complication rates unacceptable. Cornelius Binkhorst and John Pearce, among others, returned us to ECCE to achieve stable IOL fixation and eventually total sequestration of the IOL in the capsular bag, reducing inflammation. In 1967, Charles Kelman introduced phacoemulsification, and a decade later, Steve Shearing led us back to the posterior chamber as a preferred location for an IOL. Richard Kratz refined our method of anterior capsulectomy with the so-called “can opener” technique, and this was the approach I first learned in 1978 when I did my first ECCE and phacoemulsification cases while doing a fellowship with William S. Harris, MD, in Dallas.
In 1980, my good friend Calvin Fercho from Fargo, North Dakota, showed me a technique that used three to four connected long anterior capsular tears rather than multiple small punctures or cuts. This approach was the predecessor to the ultimate continuous curvilinear capsulorrhexis (CCC) developed and taught by Howard Gimbel, Thomas Neuhann and Kimiya Shimizu a few years later. The CCC significantly reduced intraoperative complications such as anterior capsular rim tear with potential vitreous loss and improved IOL centration and sequestration in the capsular bag. Of interest, either a cystotome or capsular forceps, similar to Daviel and von Graefe, were used to create the far more elegant CCC.
Now we are in a new era of innovation, advancing the art and science of CCC. The goal is to make the CCC perfectly round and of the ideal size for IOL optic overlap to enhance IOL centration and reduce tilt. For a 6-mm optic, this size appears to be ideally between 5.25 mm and 5.75 mm. This size is also compatible with modern phacoemulsification and small-incision ECCE techniques, and is further reinforced by the finding that the anterior capsule is thicker and more robust to anterior capsular rim tears in this zone.
Debate continues on whether the CCC should be centered on the capsule, pupil, line of sight or corneal apex. Ideally, the best technique would allow the surgeon to choose his or her preference, and we may learn that one is preferable over another depending on the IOL selected and the individual patient’s anatomy and corneal optics, including higher-order aberrations.
We also all want the anterior capsulotomy rim edge to be as robust as possible because anterior capsular rim tears remain, after 250 years, a potential sight-threatening complication. Many manual adjuncts have been developed, and the Verus CCC device (Mile High Ophthalmics), developed by Malik Kahook, is to me quite ingenious, simple and inexpensive.
I was an early consultant in the development of femtosecond lasers, working with LenSx and later Lensar. Beginning with Zoltan Nagy’s work with LenSx in 2008, we have confirmed that a perfectly round CCC centered and sized as we wish can be created by any of the commercially available femtosecond laser systems. These lasers are growing in popularity, but their significant expense and complexity are a clear disadvantage. In addition, the anterior capsular rim strength is at best equivalent to a manual CCC, and anterior capsular rim tears are in some series more frequent, especially during the learning curve.
Recently, simpler innovative approaches have been developed that, in my opinion, may represent a disruptive advance in our ability to reproducibly create a perfectly round, appropriately centered and sized CCC at a much lower cost than with a femtosecond laser. In addition, the anterior capsular rim strength and resistance to tear appear in early animal and clinical research to be enhanced as compared with manual and femtosecond laser approaches. I have worked with two early-stage companies as a consultant to develop the Excel-Lens CAPSULaser and the Mynosys Zepto. Both are discussed in the accompanying cover story.
For me, these two new surgical tools are extremely exciting and promise to offer every surgeon and patient in diverse operating environments worldwide a more perfectly sized, shaped and centered CCC at a more reasonable cost per procedure. In addition, these new technologies promise to offer the surgeon and patient a stronger anterior capsular rim, reducing further the potential sight-threatening complication of an anterior capsular rim tear. Time will tell, but I believe these devices, and perhaps others in development with similar features, will join the critical evolutionary events described above as another important and disruptive step in the quest to develop the safest, most reliable and cost-effective method of cataract removal and IOL placement.
Disclosure: Lindstrom reports he is a medical advisory board member and consultant to Excel-Lens and Mynosys.