New IOL injector yields optimum implantation with reduced learning curve

Stefanie Petrou-Binder MD in Ludwigshafen, Germany

THE new and improved Unfolder Silver Z injector significantly simplifies the implantation of Clariflex (AMO) IOLs compared to the unit it replaces, reported Austrian researchers at the Congress of the German-Speaking Association for Intraocular Lens Implantation and Refractive Surgery (DGII).

Ulrich Klemen MD conducted a prospective study which included 32 patients with bilateral cataract who underwent cataract surgery on both eyes within four weeks between September and November 2002.

The surgeons implanted the foldable three-piece silicone Clariflex lenses in each eye, randomly implementing the Unfolder-injector in one eye and the new Unfolder Silver Z model for implantation in the fellow eye. Patients ranged in age from 67 to 98 years.

"The use of injectors to implant IOLs only precludes contamination when both haptics are introduced into the capsule sac without additional manipulation. Of the 32 cases in which we implemented the Unfolder Silver Z, not a single one required the use of an accessory instrument (hook) to fixate the capsule sac in order to introduce the second haptic or to centre the IOL. Aside from contamination-free implantation, we achieved highly satisfactory IOL centration with this injector," Dr Klemen MD reported.

Correct positioning of the CLARIFLEX IOL ín the cartridge: the passage of the IOL through the cartridge can be observed completely.	2.6 mm Incision; the leading haptic is placed into the capsular bag.
After unfolding of the IOL the second haptic can be also positioned into the capsular bag without a second instrument: "one step procedure".	Self-centration of the Clariflex IOL at the end of surgery.

All operations consisted of a 2.6 mm post-limbal incision in the steepest meridian, clear corneal cut, hydrodissection, in-the-bag phacoemulsification, I/A, capsule polishing and IOL implantation using an injector through the original incision.

Dr Klemen carried out IOL implantation with the Silver Z injector in four steps. First, he carefully pushed the IOL to the front of the injector and then began to rotate the injector while simultaneously turning the plunger enough for the leading haptic to enter the capsule sac.
He then injected the IOL optic into the capsule sac, and finally also the second haptic, by drawing back slightly on the plunger first, to grip the haptic better, and then injecting it completely into the sac while continuing to rotate the instrument.

He commented on the ease of implantation, spontaneous IOL centration in the capsule sac, additional manipulations (hooks, rotations), as well as the postoperative outcome.
In terms of the ‘ease of implantation’, the results showed that all IOLs (in 32 eyes) implanted with the Silver Z required ‘one-step’, ie no additional manipulation. A total of 94% (30 eyes) of these IOLs were centred.
Of the 32 partner eyes which received IOLs with the traditional Unfolder, surgeons implanted 14 (43.7%) in ‘one-step’, while 18 (56.3%) required additional manipulation. Some 90% were centred.

The functional results were excellent, revealing target refraction in 90% of eyes. The uncorrected distance visual acuity was at least 0.5 in 31 of the 32 patients.
Three eyes developed induced postoperative corneal astigmatism of more than 0.5 D. The researchers were able to reduce the existent corneal astigmatisms by a mean of 0.2 D to 0.25 D because of the incision location in the axis of the steepest meridian.

On the first postoperative day, three Unfolder eyes had transiently raised IOP, two showed corneal oedema and another three had decentration of over 0.5 mm. The Silver Z eyes revealed one case of transiently increased IOP, two cases of corneal oedema and one decentration over 0.5 mm.

Dr Klemen asserted that the lack of intraoperative manipulation in the Silver Z-implanted eyes was ostensibly responsible for the lower incidence of decentrations, anterior eye segment irritations and mildly elevated, transient intraocular pressure seen on the first postoperative day in traditional Unfolder eyes. The eyes which developed corneal oedema improved within a few days postoperatively.

While more than 30% of IOLs implanted using the traditional technique required the additional help of a hook to enter the device securely into the bag, this was reduced to zero with the newly developed injector which employs the ‘turn-and-push’ technique.

He reiterated that the implantation of three-piece Clariflex IOLs with the newly developed Silver Z injector showed easier implantation, lower intra and postoperative complications, enhanced self-centring, a lower risk of contamination through ‘one-step’ implantations and no learning curve for surgeons already familiar with the Unfolder.

"Improvements in injector systems run parallel to the new developments being made with IOLs which have improved optical characteristics, more efficient PCO inhibition and reliable centration results. The ‘turn-and-push’ technique we employed with the new Unfolder Silver Z injector avoided such complications as the uncontrolled unfolding of the device, IOL microruptures and additional manipulation with a second instrument for in-the-bag fixation," Dr Klemen said.
He averred that future developments in injector technology should include injectors which can be implemented uni-manually to facilitate bimanual manipulations when required.
He also hoped for a further reduction in the incision width of below 2.6 mm to reduce the postoperative risk of induced corneal astigmatism, as well as to increase wound stability.

Ulrich Klemen MD
AÖ Krankenhaus St Pölten, Austria
augenabteilung@kh-st-poelten.at

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