Cataract surgeons' wish list for intraocular lens insertion systems doesn't ask for much: ease of use for surgeon and assistant, insertion through the smal-lest incision possible, consistency of delivery and un-folding of the lens. A disposable plastic material and a one-handed injector system make the list as well. Here is a review of device manufacturers' at-tempts to meet these surgeon demands.
Filling the Wish List
Steve Dewey, MD, of Colorado Springs, Colo., swore by IOL insertion with forceps for years. Even as an early user of some insertion systems from Advanced Medical Optics, including the Sapphire system, Dr. Dewey preferred forceps delivery.
"I could more consistently get the lens into the capsular bag," he says. He saw little clinical difference between the 3.9-mm incision size with forceps and 3.5-mm incision with the Sapphire, and almost no incidence of endophthalmitis. Subsequent designs of insertion systems brought the incision size down to 2.8 mm, he says, but he still could not always get the lens into the capsular bag in one step.
"A good forceps user can get the optic into the bag in one step," he explains.
But AMO's Emerald line of IOL delivery systems has converted Dr. Dewey to inserter use. For him, AMO's Unfolder Emerald, and its more recently launched Emerald Ease inserter, come close to grant-ing his wish list. He says the insertion system is so user-friendly that he no longer loads the IOL himself; his staff does it.
"This saves at least a minute per case," he reveals.
With the Emerald, Dr. Dewey currently uses an unenlarged incision of
2.8 mm and reports no in-cision-related problems. He declares that he will exclusively use the Emerald Ease and pull out the forceps only for the rare case of loose zonules or pseudoexfoliation where a very gentle insertion is called for.
Rafael Chan, senior product manager for IOLs for Alcon Laboratories, says the lens that would answer all of the requests on the cataract surgeon's wish list would combine the best of everything.
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| Staar Surgical's IOL delivery systems are made of a disposable plastic in both twist-style and plunger-style options. | |
"It would have a pre-loaded cartridge that would go through the smallest incision possible," he says. "It would be user-friendly and totally sterile. And, it would deliver the best optical quality too."
Manufacturers are moving closer to that goal, says John D. Hunkeler, MD, of Kansas City, Mo. "Where we need to be going, in my opinion," offers Dr. Hunkeler, "is toward a totally closed system, no-touch insertion of implant, where the implant is de-livered into the operating room pre-loaded into the insertion system. This is the Holy Grail." He says that each new design he sees offers the surgeon an incremental improvement. In addition to sterility, a pre-loaded cartridge would ease surgeons' concerns about incorrect power of the IOL used.
"With today's quality control in the factory, I would worry less than I do now about verifying the power, quality and appearance of a pre-loaded lens," he explains.
Current Efforts
Last spring, Bausch & Lomb launched its SofPort platform, officially combining the SoFlex SE IOL and the MPort SI injector. Blake Mich-aels, B&L's director of marketing for cataract products (U.S.), says that one innovation of the SofPort platform is the M-fold of the IOL.
"The M-fold allows a lens to come out essentially flat within the anterior chamber or within the capsular bag, wherever you are aiming it," explains Mr. Michaels. He reports that this flat delivery happens consistently and safely through an incision size of about 2.85 or 2.9 mm.
"Incision size is a criterion when we are developing a new insertion system," says Giulia Newton, AMO's senior marketing manager, IOLs. "Any new system has to be the same or smaller in terms of incision size. I don't think surgeons are going to accept larger incisions even if an inserter is easier to use."
Alcon's Mr. Chan agrees that surgeons want to minimize any effects of enlarging the phaco incision. He says that while the Monarch II IOL labeling says 3.2 mm or less, he notes that the final incision size depends on the surgeon's technique and the type of cartridge used. Mr. Chan explains that Alcon offers three cartridge sizes for its different AcrySof lenses. The smallest incision size results from use of the "C" cartridge, designed for delivery of the AcrySof single piece 5.5 mm optic. "That's the true sub-3 mm cartridge," he says.
Design Details
Design improvements are manifested in clear plastic inserters, disposable systems, increased lubricity in the cartridge and a choice between inserters that can be used with one hand (plunger or syringe style) or two hands (screw-style inserters).
The ability to see the optic in the cartridge as it moves through the inserter is a plus because you can see the lens at every stage, says Dr. Dewey.
"In loading, the optic may have been pushed too far forward. I can see that and exchange the IOL. Or I might notice that the haptic is not in the proper place," he explains. Anything that helps him to do the insertion right the first time helps, says Dr. Dewey, especially when the patient is uncooperative.
The pre-loaded cartridge shows up frequently on the cataract surgeons' wish list, because it would take human error out of the loading process completely. Although Dr. Dewey finds a misloaded cartridge in only one of about 300 cases, he admits that "a preloaded cartridge would be good in cases where a surgeon does not have consistent people assisting him, where people rotate on your surgical team or where there is a lot of staff turn-over."
Kansas City's Dr. Hunkeler believes that a totally disposable insertion system makes sense.
"Having all the components packaged together certainly has an appeal, especially for people who travel from hospital A to surgical center B, and arrive without their handpiece," he says.
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| Clear plastic components of Bausch & Lomb's SofPort System allow visualiz-ation of the IOL from placement in the cartridge to insertion in the capsular bag. |
But are we at a point yet where it is mandatory? Dr. Hunkeler does not think so. As the use of disposable surgical instruments spreads from Europe to Canadian hospital settings, however, demand for totally disposable systems in the United States is not far off.
One Hand or Two?
Dr. Hunkeler insists that the choice of a one-handed inserter over a two-handed piece is as individual a situation as being right-handed or left-handed. Offering a one-handed inserter is an improvement in ergonomics, he says, and allows the surgeon to use his dominant hand. The creation of plunger-style inserters is yet another incremental improvement, he says.
Dr. Dewey reports that he is getting used to insertion with one hand, using the Emerald Ease. He thinks the syringe-style inserter might be an ad-vantage in an uncooperative patient, where the surgeon could use his other hand to stabilize the eye. He also notes that the lens delivers differently with the syringe-style inserter.
"There's a more direct application of force with the plunger, whereas with the screw-type, it modulates the force for you," Dr. Dewey says. "With the plun-ger, you need to be aware of the pressure you put on your injector."
Staar Surgical has offered its MicroStaar injector in both a twist and a plunger-style advance for a number of years, since they changed from offering metal injectors to disposables. Staar's Director of Sales Rick Prell reports that surgeons with a more aggressive technique tend to like the plunger-style injector.
"They get more of a feel for any resistance they get from the lens with the plunger, compared to when they twist down," he says.
Alcon's Mr. Chan reports that he's had requests from surgeons for both one-handed and two-handed inserters.
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| ASICO's titanium Royale Unihand Injector offers surgeons who prefer the Alcon AcrySof IOL the option of a one-handed plunger-style inserter. |
"The ASICO handpiece has been validated with our cartridges," confirms Mr. Chan. He explains that the ASICO product provides an option to the surgeon and it's his choice if he would like to use the third-party handpiece.
Closing Out the Wish List?
While an injector system that meets the wish-list requirements is not yet in the hands of American surgeons, one may just be in use already in Japan and Europe.
Mr. Prell explains that Staar is close to offering a pre-loaded, totally disposable injector system to the American market. (Another surgeon hints that Alcon is at least six months away from introducing such a product as well.) Staar currently sells a pre-loaded cartridge for three-piece silicone lenses in Japan called the KS-1, and introduced it last month in Europe. He explains that the pre-loaded lens and the injector are packaged together in an en-closed, sterile system. The plastic rod of the inserter advances with a push-and-twist combination that can be done with one hand. Incision sizes are reported at 2.8–3 mm, and can save 30 seconds to one minute per case.
"For high-volume surgeons," says Mr. Prell, "this increase in efficiency will be extremely valuable."
Mr. Prell reports that Staar does not yet have a name for this product in the U.S. market, but that he hopes for U.S. Food and Drug Administration approval of the system in mid-2004.
