While an overwhelming majority of patients are satisfied with their presbyopia-correcting lenses, there are some who cannot tolerate the vision. As ophthalmologists we are great at screening out poor candidates for these technologies, but even the “ideal patient” may end up extremely dissatisfied. In those cases, exchange of the intraocular lens (IOL) may be the only option. There are many techniques to perform an exchange, but the basic tenets remain the same:
- Control the environment as much as possible. Specifically, I recommend a retrobulbar block for all lens-exchange cases. Although it may seem as though an exchange in a patient with intact bag will be simple, the situation can quickly change. Furthermore, while slight ocular movements during cataract surgery can be insignificant, they can be devastating in lens-exchange surgeries, since the instruments used are typically sharper, and two instruments are not in the eye at all times to minimize the patient’s tendency to look around. When patients undergo cataract surgery, they expect to be able to see at least a little upon leaving the surgery center. Lens-exchange patients easily understand that their surgery will be different than cataract surgery and are not disappointed when informed that they will wear a patch until the first postoperative day.
- Remove the lens while maintaining the integrity of the capsular bag. IOL exchange performed in the early postoperative period is a simple task. For patients who have had surgery several months or years prior, the lens can be very adherent to the surrounding capsule. In these cases, a helpful way to dissect the lens away is to place the viscoelastic on a 27-gauge needle and place it under the anterior capsulorhexis. With a careful injection and sliding motion of the needle, the anterior capsule can be lifted off of the central optic. Once this has been done, viscoelastic can be injected both under the optic and along the course of the haptics to free them from the bag.
- Manage vitreous accordingly. Many of these patients have already undergone YAG capsulotomy, and so removing the lens without encountering vitreous may be difficult. Keeping the eye full of viscoelastic, and injecting a dispersive viscoelastic under the lens before removing it, are methods of keeping the vitreous in the posterior chamber. In cases of open capsules, I prefer to use a large optic lens such as the Alcon MA50BM so that the optic may create a manhole cover on top of the anterior capsulorhexis and prevent and vitreous prolapse. In cases in which vitreous does manage to enter the anterior chamber, intracameral triamcinolone is a useful adjuvant to stain and help visualize the vitreous to ensure a complete cleanout.
- Cutting the original lens prior to removal. While some ophthalmologists prefer to fold the lens within the anterior chamber and then remove it, I have always found it easier to simply bisect the lens or cut it >50% across and dial it out of the corneal incision. To cut the lens, the best device I have found is the Packer/Chang IOL cutters and microincision holding forceps from Micro Surgical Technology. Able to fit through a paracentesis, these allow for easy manipulation of the intraocular lens while within the anterior chamber.
- Implanting the new lens. In cases of lens exchange, I almost always use a three-piece lens and place it within the sulcus. I have seen many videos of heroic maneuvers to place a lens within a capsular bag that is not completely intact, and I do not see the benefit of it. I do believe that an important maneuver with sulcus implantation, however, is to reverse-capture the optic through the anterior capsulorhexis. This results in excellent IOL centration and stability. IOL power should also be calculated the same as bag implementation.
I must acknowledge the following ophthalmologists for sharing these tips with me: Drs. Robert Cionni, Elizabeth Davis, and Eric Donnenfeld. By following these pearls, ophthalmologists who perform lens-exchange surgery or are considering performing lens-exchange surgery will find that this procedure can be performed safely and efficiently.