How can we correct high myopia with a phakic angle-supported IOL without too many problems during surgery? After 10 years of clinical study, the AcrySof Cachet (Alcon Laboratories, Inc., Fort Worth, Texas; Figure 1) seems to provide a good solution. This phakic lens is designed to assure safe and easy implantation. It is made of the same soft, flexible hydrophobic acrylic material as other AcrySof IOLs, which allows the lens to be folded and inserted through a small incision of 2.6 mm. Use of the AcrySof Cachet requires careful patient selection and IOL calculation. In this article, we describe our surgical experience and give readers some pearls and tips for IOL implantation.
PROCEDURE
One hour before surgery, we administer pilocarpine
2% drops until the pupil is constricted. For young
adults, we prefer general anesthesia because postoperative
recovery time is shorter and a curare drug is not
necessary. The advantages for the surgeon include a
shorter operating time compared with topical anesthesia.
In our opinion, local anesthesia should be never recommended.
The first surgical step is to perform a 2.6-mm clear corneal incision on the steepest meridian. Then a miotic drug is injected into the anterior chamber to achieve the best possible pupil constriction. After creating a sideport incision with a 15° knife, the second step is to inject an ophthalmic viscosurgical device (OVD) close to the iridocorneal angle at the 6-o'clock position. Try to inject all the OVD over the iris. Avoid the pupil center, and ensure that no OVD goes under the iris. An OVD with a low molecular weight (ie, hyaluronic acid 0.85%) allows correct insertion of the haptics and easier removal of the OVD at the end of surgery.
In the third step—before loading and delivering the lens—fill the Monarch III P-Cartridge (Alcon Laboratories, Inc.) completely with OVD. This cartridge is specifically designed for Cachet phakic IOL insertion. We recommend wetting the IOL before manipulating and inserting it into the cartridge. Then, using the dedicated forceps, remove the lens from the case by grasping the center of the optic across three-quarters of the lens. The anterior surface should be face up; verify the clockwise direction of the side-up indicators located on the lens.
Before inserting the IOL into the back of the cartridge, fold the haptics together in the so-called dive position (Figure 2). This position is obtained by touching both the haptics and gradually placing them into the internal lateral wall of the cartridge. When the dive position is obtained correctly, the left loop should remain close to the right.
It is important to visually verify under the microscope that the lens advances slowly and freely into the cartridge. Both of the footplates must be loaded symmetrically and in the dive position. In case of bad or incorrect loading, we recommend reloading the IOL into the cartridge. This IOL is elastic, allowing the lens to be easily reloaded if necessary.
The fourth step is to slowly insert the cartridge through the incision. Use a manipulator through the sideport incision to assist in introducing the cartridge without forcing the incision. The second instrument helps the surgeon to stabilize the eye and maintain centration (Figure 3). Lens implantation must be done carefully, with slow maneuvers that allow the lens to unfold gently and properly. We like to insert the distal part of the cartridge beyond the middle of the pupil. Then we start to inject the IOL until we are able to see the two distal loops. At this time, stop IOL delivery and wait until the two distal foot loops open into the angle (Figure 4).
When the optic is inserted into the eye (in front of the pupil), the posterior haptics should remain outside the eye until the surgeon presses them into the angle of the anterior chamber. For this maneuver, push between the bridge and the footplate with a positioning hook (Figure 5). The surgeon must not advance the lens by pushing on the bridge, which is rigid, because it may create anomalous vaulting resulting in lens-endothelium contact.
The fifth step is removal of the OVD. We prefer washing it out with BSS (Alcon Laboratories, Inc.) using a Sauter cannula instead of a mechanical I/A probe. BSS is injected into the angle at the 6-o' clock position as the cannula is used to push down on the optic and the inferior edge of the main incision. This procedure is repeated until the OVD is flushed out. This technique keeps the lens stable and placed in the angle (Figure 6). The last step is to hydrate the corneal incisions (Figure 7). We prefer unilateral implantation in a surgical session.
CONCLUSION
During routine cataract surgery cases, we are used to
working with a lot of space in the anterior chamber.
Because there is less space in the phakic eye (more or
less 4 mm in the center of the eye), our goal is to work
in the anterior chamber without touching the crystalline
lens or the endothelium. We must not forget
that this eye has no disease*mdash;it is only a myopic eye.
Any expert cataract surgeon beginning this new surgical procedure must change his standard approach. He must first undergo training with an experienced surgeon. It is important to carry out slow maneuvers, especially during IOL implantation, and avoid any quick movement inside the anterior chamber. Do not forget to check for correct IOL placement at all times. Finally, consider that the IOL might spin around during the OVD removal. Therefore, if you can, choose passive manual OVD removal.
Enjoy our surgical technique, and take care to continue practicing.
Simonetta Morselli, MD, is Chief of the Ophthalmic Unit, San Bassiano Hospital, Bassano del Grappa, Italy. Dr. Morselli is a member of the CRST Europe Editorial Board. She states that she has no financial interest in the products or companies mentioned. She can be reached at email: simonetta.morselli@gmail.com.
Antonio Toso, MD, is a Consultant and Vitreoretinal Specialist, Ophthalmic Unit, San Bassiano Hospital, Bassano del Grappa, Italy. Dr. Toso states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: antonio.toso@gmail.com.