Injectors provide advantages over forceps

Injectors allow safer, more sterile IOL implantation through smaller incisions, but the instruments need perfecting, a surgeon says.

MILAN, Italy – The advantages of injectors over forceps are becoming more and more apparent in small-incision cataract surgery.

“A first, obvious advantage is that, unlike forceps, they can be introduced into small 2.8 mm apertures,” said Pietro Giardini, MD. “Once the goal of small-incision surgery has been achieved, it seems only natural to favor a technique that maintains the small incision.”

Dr. Giardini summarized the conclusions of a debate on the topic here at the Satelcataract meeting.

Disadvantages of forceps

“IOL implantation with forceps requires double maneuvers of the folder and the holder,” said Dr. Giardini. “Although these maneuvers are standardized and fairly easy to master, the greater number of surgical steps creates a higher risk of contamination. Also, the advantage of a lesser quantity of viscoelastic used in the insertion with forceps is outweighed by the fact that forceps require a larger incision.”

Further problems may arise in the folding maneuvers. Some types of silicone IOLs are difficult to hold when moist, Dr. Giardini said, possibly resulting in imperfect, asymmetric folding. “Silicone IOLs also tend to unfold jerkily and are difficult to control at this stage,” he said. Acrylic IOLs may be rather stiff and sticky, he said; “They resist folding, and once they are bent they cling together and open up with difficulty.” They can also be contaminated by particles released by the forceps.

Sterile, direct implantation

“Most of these problems can be overcome with the use of injectors,” said Dr. Giardini. “All injectors of the latest generation are disposable and sterile. The lens is inserted in the capsular bag under sterile conditions with just one shot rather than in two steps. Injectors make implantation gentler and easier to control. Silicone IOLs unfold more gradually and smoothly and are more easily implanted even when they are moist. They can also be recaptured and injected a second time if necessary.”

Injectors can be a valuable help in difficult cases. “With small pupils, the implantation is better controlled and safer and the lens is more easily and securely delivered in the capsular bag,” Dr. Giardini said.

The advantage of retaining a small incision is particularly important when dealing with a shallow chamber. There is no risk of viscoelastic discharge during the implantation maneuvers, and more viscoelastic can be injected with the IOL for better control of surgical maneuvers in the anterior chamber.

“When using injectors, a brief training period enables a nurse to take care of the IOL preparation. Surgical times are therefore shortened,” Dr. Giardini added. “However, the priming of the lens into the cartridge can be rather awkward, and when incorrectly performed may cause severe damage to the lens. With some injectors, the progression of the lens inside the cartridge cannot be visualized. If something has gone wrong, the surgeon may not be aware of it,” he said.

Potential problems

“We cannot deny that injectors have this and some other disadvantages,” Dr. Giardini admitted. “Most of them require the use of both hands, so the unfolding of the lens cannot be assisted with a spatula through the side port.”

Surgeons should also be aware that each type of injector requires specific training, as IOL positioning and implantation techniques change from type to type. “In some cases, the injector must be rotated and counter-rotated for correct positioning of the IOL. If these maneuvers are not carried out correctly, the lens may be inserted upside-down in the capsular bag and need repositioning.”

Inside long, thin cartridges, acrylic IOLs produce strong friction within the internal walls of the instrument. This may damage the optic or the loops of the lens. The problem may be overcome by using viscoelastic inside the injector to protect the lens, but “the increased quantity of viscoelastic may provoke in the patient under topical anesthesia an unpleasant feeling of pressure during surgery,” Dr. Giardini noted.

Each one different

“Pros and cons vary according to the type of injector used. On balance, all injectors of the new generation have equally good standards, but surgeons must be aware of the advantages and disadvantages they present,” said Dr. Giardini.

He gave the audience a useful summary of the specific features of the five best known injectors, as outlined in the accompanying chart.

“Sometimes the injector of a certain make can be used with the IOL produced by other manufacturers. Good knowledge and intelligent use of the different types of injectors allow the implantation of IOLs which are not normally supplied with this kind of instrument,” Dr. Giardini said.

Allergan Unfolder for silicone and acrylic IOLs.	Bausch & Lomb Mport.
Pharmacia CeeOn EasySert.	Injectors (from top down): Mport; AMO Unfolder for acrylic IOLs; AMO Unfolder for silicone IOLs; Alcon Monarch; MicroSTAAR Injector System; Pharmacia CeeOn EasySert.
The cartridges for different injectors.	The cursors of different injectors.

He expressed hope that in the near future, preassembled injectors containing IOLs of different powers will be available. This would make the entire procedure easier, faster and more sterile.

“At the present time, I would recommend young surgeons to do their first implants using forceps. Then they can switch to injectors, bearing in mind that each type of injector is different and requires specific training,” said Dr. Giardini.

For Your Information:

• Pietro Giardini, MD, can be reached at Casa di Cura Poliambulanza, Via Bissolati 57, 25124 Brescia, Italy; (39) 030-3515204/3515784; fax: (39) 030-3515967. Private surgery: (39) 031-269242; e-mail: pgiard@inwind.it. Dr. Giardini has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.