For most surgeons, each year of practice brings at least one new change in surgical technique or in the devices and technologies we use. This past year was especially exciting for us, as we witnessed the launch of a microincision cataract surgery (MICS)- compatible IOL that we had worked with in US Food and Drug Administration (FDA) clinical trials.
LENS DESIGN
The Incise Microincision IOL (Bausch + Lomb) has the sharpest edge radius of any IOL (less than 5 μm) and a continuous 360º square-edge profile—design features that help to prevent cell migration and decrease the incidence of posterior capsular opacification (PCO). The acrylic lens material has 22% water content and contains more hydrophobic monomers than other acrylic IOL materials, making Incise stiff and resistant to tears and other surgical trauma (Figure 1). The combination of the material and a dedicated single-use injector system enables the IOL to be implanted through an incision as small as 1.4 mm.
Our adventure with the Incise IOL started in March 2012, in Toulouse, France, where we were briefed on the protocols of the FDA study and participated in a wet lab to become familiar with the lens’ characteristics. We also had the opportunity to fold the IOL into the Incise Viscoject bioinjector and practice implantation through a 1.5-mm incision in an animal model.
Given our positive experience with the MICS-compatible Akreos MI60 IOL (Bausch + Lomb), with its four angulated haptics designed to create capsular bag stability, we had high expectations for the Incise. Our work in the wet lab suggested that the Incise would deliver a better barrier against PCO, and we returned to our clinic excited to begin our participation in the clinical trial.
We immediately enrolled 25 patients with cataract and no other ocular pathologies who were scheduled for MICS, and then we waited to obtain authorization from the European Commission to proceed. We were cleared to start implanting the Incise IOL in March 2013. For the purposes of this study, eyes were randomized to either receive the Incise or the Akreos MI60.
OUTCOMES
We performed coaxial MICS through a 1.8-mm incision, but other participating centers used a biaxial wound-assisted technique with a 1.5-mm incision. In all centers, the FDA required measurement of the incisions with calipers (Figure 2A). We found that the Incise IOL was easily delivered into the capsular bag through the incision, but, compared with the implantation maneuver we use for the Akreos MI60, implantation required more continuous force (Figure 2B).
Postoperatively, patients had good quality of vision and were able to differentiate the eye implanted with the Incise IOL from the eye implanted with the Akreos MI60. (In the future, we plan to study the aberrometric differences between these IOLs.) The mean UCVA with the Incise was 20/25, and the mean postoperative refraction spherical equivalent was -0.06 ±0.72 D; we were especially impressed with the predictability of the postoperative refraction.
Retroillumination photographs were used to document the lens position (Figure 3). At 6 months, the Incise IOL remained stable in the capsular bag, and there were no cases of lens decentration. There was also no observable PCO.
A BETTER LENS
The design of the Akreos MI60 is beneficial for complicated situations; however, the enhanced acrylic material of the Incise IOL has allowed us to achieve the same excellent stability of the Akreos with a better PCO rate1. Additionally, the 22% water content has eliminated the glistening effects from the IOL.
When we started this study, we had little awareness of the rigidity of the Incise IOL compared with the Akreos MI60. The first time we implanted it in the wet lab, we had some difficulty controlling the injection force of the 1.5-mm injector. On the plus side, because the lens completely fills the capsular bag, there is no need to check and manipulate the IOL position after implantation, which is advantageous in eyes with small pupils. The lens is also appropriate for use in combined cataract and vitreoretinal or glaucoma surgery, after which postoperative intraocular pressure can spike or drop, shallowing the anterior chamber.
PEARLS
As with any new lens, there were hurdles to overcome during the learning curve with the Incise Microincision IOL. Below we offer several pearls from our early experience.
Pearl No. 1: Practice in a wet lab. We suggest practicing loading the injector and implanting the lens in the wet lab to fully understand how it unfolds and is delivered into the capsular bag. This is helpful to experience and learn the proper continuous and gentle force required for injection.
Pearl No. 2: Do not to leave the IOL in the cartridge for an extended period before implantation. If left in the cartridge for too long, the IOL can lose part of its water content and, as a result, need more time to unfold in the capsular bag. We also suggest using only the dedicated injector and loading the IOL yourself under the microscope, paying attention so as not to trap the haptics in the cartridge.
Pearl No. 3: Inject the IOL in a slow, controlled manner. Take ample time to deliver the IOL gently into the capsular bag. When injected too quickly, the IOL can rebound out of the incision. Use a manipulator in your second hand through the sideport incision to steady the eye during injection.
Pearl No. 4: Remove the ophthalmic viscosurgical device (OVD) from behind the IOL. Because the Incise IOL is rigid and stable, do not be afraid to go underneath the lens to remove any remaining OVD. In our experience, the lens’ four-point haptics reduce the amount of OVD trapped underneath the IOL.
CONCLUSION
In 2013, our MICS technique did not change much, but we did adopt a new IOL. We learned a few valuable lessons along the way that have helped us to enhance our results and provide patients with even better outcomes. We look forward to seeing what 2014 will bring.
Simonetta Morselli, MD, is Head of the Ophthalmology Department, S. Bassiano Hospital, Bassano del Grappa, Italy, and is a member of the CRST Europe Editorial Board. Dr. Morselli states that she has no financial interest in the products or companies mentioned. She may be reached at e-mail: simonetta.morselli@ gmail.com.
Antonio Toso, MD, is Head of the Vitreoretinal Surgery Unit, Ophthalmology Department, S. 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.
- Gangwani V, Hirnschall N, Koshy J, Crnej A, Nishi Y, Maurino V, Findl O. Posterior capsule opacification and capsular bag performance of a microincision intraocular lens. J Cataract Refract Surg. 2011;37(11):1988-1992.
