Slow, controlled injection key to successful IOL implantation

September 15, 2004

San Diego-Implantation of the AcrySof ReSTOR (Alcon Laboratories Inc.) anterior chamber, angle-supported, phakic refractive IOL is a "very straightforward procedure," according to Michael C. Knorz, MD.

At the American Society of Cataract and Refractive Surgery annual meeting, Dr. Knorz shared his pearls to achieve the best possible results while implanting this lens in myopic patients.

One of the first steps when implanting this lens is to check the lens sizing by measuring the white-to-white distance to confirm the size of the lens. The Monarch II injector with the B cartridge (Alcon Laboratories) is filled with a viscoelastic (ProVisc, Alcon Laboratories) first and then the IOL is loaded. An iridotomy can be performed, although it is not required.

The IOL is delivered into the eye while the anterior chamber is filled with viscoelastic and the pupil is constricted, similar to implantation of any other anterior chamber IOL, explained Dr. Knorz, clinical professor of ophthalmology, Faculty of Clinical Medicine, University Hospital of Mannheim, Mannheim, Germany.

The lens is a single-piece, foldable, acrylic device and has a 6-mm optic with a slight vault. It should be slowly released into the anterior chamber using a very slow, controlled injection process.

"The leading haptics are brought into position first, much like the position a diver assumes when diving into water. The IOL is placed into the cartridge and pushed forward. Proper loading of the IOL is paramount to ensure its correct orientation when it enters the eye, which is one of the most important parts of the procedure," he said.

A 3.2-mm limbal incision is made after administering topical anesthesia. Intracameral anesthesia is not necessary. One side port is used for manipulation.

"I like to see some bleeding during the procedure. Esthetically, it is unappealing, but I believe that there is much stronger wound stability, which is why I prefer limbal incisions," Dr. Knorz said.

Implantation procedure

After the anterior chamber is filled with the viscoelastic and the pupil is constricted with pilocarpine 2% drops, the lens is injected. As the lens is injected into the anterior chamber, Dr. Knorz likes to use a spatula in his right hand to stabilize the eye through the side-port incision. This eliminates the need to push the IOL hard. Forceps can be used, grasping the eye at the limbus, but that usually hurts more, he said.

As the lens slowly advances, it is necessary to wait for the leading haptics to expand fully to prevent their touching the en do the lium. The lens is slowly advanced until the leading haptics are in the opposite angle. The injector is then withdrawn while the trailing haptics are outside the eye.

"If the injector was not withdrawn, there would be too much pressure on the opposite angle. The trailing haptics are then introduced and tucked into the anterior chamber angle one by one. After this, the viscoelastic material is extracted from the anterior chamber using irrigation with aspiration and either bimanually or by a single port," Dr. Knorz demonstrated.

"This is a very straightforward implantation technique. I like to use a single-hand irrigation/aspiration probe to aspirate the viscoelastic. It is very important that all the viscoelastic material is removed. If any is left in the eye, there is the risk that the IOP will be very elevated the first day after the surgery, which may cause problems with the pupil," he said.

As Dr. Knorz withdraws the probe, he checks through the side-port incision at the same time to avoid any shallowing of the anterior chamber. Finally, the positions of the haptics are checked inside the angles on both sides, even though in most cases the haptics position themselves well inside the angles.

This IOL was successfully implanted in 102 patients in a European clinical investigation of this lens.