Alan S. Crandall, MD
Dislocation of intraocular lenses (IOLs) can occur in a variety of different settings. The common causes include trauma, chronic uveitis, and previous retinal and/or vitreous surgeries; however, the most frequent comorbidity is the presence of pseudoexfoliation.1
Patients with pseudoexfoliation are known to develop spontaneous, delayed IOL dislocations that can occur at almost any time after uncomplicated in-the-bag surgery, with a mean onset at of 8.5 years postoperatively.1 The presence of a capsular tension ring (CTR) does not entirely prevent the subluxation (or dislocation) of the bag-IOL complex but it can be helpful for repositioning of the IOL.2 Techniques that may reduce the risk of this complication include pupil expansion to enable an adequately large 5- to 5.5-mm capsulorrhexis diameter. Strategies to reduce iatrogenic zonular trauma include gentle hydrodissection, judicious use of CTRs, tangential rather than radial stripping of cortex, and removing as many lens epithelial cells from the anterior capsule as possible. These strategies decrease the risk of capsulophimosis, but it will take many years to understand whether these maneuvers reduce the rate of late bag-IOL dislocation.2
The surgical management outlined in this chapter assumes that the IOL itself is in good condition and that the patient was previously seeing as well as expected. Other IOL exchange techniques described elsewhere in this textbook must be used if there is damage to the IOL or haptics or if extensive Soemmering ring formation necessitates removal of the capsule.
A lasso technique can be used to secure the subluxated IOL complex regardless of whether or not there is a CTR. If the complex is completely dislocated posteriorly, then combined retinal pars plana vitrectomy and IOL retrieval surgery is needed. However, once the IOL complex is elevated back to the pupillary plane, it can be fixated by any variety of lasso or haptic fixation techniques after the haptics are externalized (eg, glued intrascleral haptic fixation, Yamane double-needle technique, or scleral-sutured IOLs using Hoffman pockets).
Regardless of whether the bag-IOL complex includes a CTR, the preparatory steps and anesthesia are the same. Prior to entering the operating room, the eye to be operated on will be marked and the surgical plan is reviewed with the patient and his or her family (if present). Although the plan is to perform a “simple” lasso refixation, the eye’s anatomy may dictate a change in surgical technique. An intravenous line is started to allow for adjunct medication. Topical anesthesia is initiated with 1% lidocaine given at least 3 times separated by 5 minutes. Lidocaine gel is placed in the fornix immediately prior to moving into the operating room suite, and the patient is instructed to keep his or her eyelids closed. Although other surgeons may prefer to dilate the pupil preoperatively, I use intracameral 1% unpreserved lidocaine with unpreserved epinephrine for surgical anesthesia and dilation in the operating room.
When starting to gain experience with this technique, a retro- or peribulbar anesthetic block may be preferable based on surgeon preference.
Lasso Technique With Capsular Tension Ring
When the IOL complex includes a CTR, the conjunctiva openings can be made along any axis, and I usually select positions that make for easy ergonomic access. This may not always be possible in the presence of a bleb post trabeculectomy or other anatomy that dictates specific locations for the sutures. Once in the operating room, the eye is prepped and draped. I will make a stab incision and inject the anesthetic solution, which also dilates the pupil. Many patients with small pupils due to pseudoexfoliation, uveitis, or prior trauma will require iris hooks to visualize the bag-IOL complex. If needed I use standard Grieshaber iris hooks (Alcon Laboratories, Inc) because they are flat and easy to place. A Mendez ring is used to ensure that the sutures will be located 180 degrees apart (Figure 15-1).
Next, unless a retro- or peribulbar anesthetic block was given, a 30-gauge needle is used to inject the same lidocaine mixture sub-Tenon’s in both suture quadrants. Westcott scissors are used to open 3 to 4 mm of conjunctiva, and Tenon’s is dissected to expose bare sclera. Light cautery is used to aid in visualizing the anatomy. There are 2 ways to lasso the IOL complex. The first is similar to the original technique described by Kirk and Condon.3 After first identifying the surgical limbus, look for the blue line of transition fibers. This landmark should be at the same location in all quadrants and using it will allow exact matching of the suture sites to avoid IOL tilt and decentration. Two locations several millimeters apart and located 2 mm behind the blue transition line are marked with calipers (Figures 15-2 and 15-3).
A sharp tapered diamond stab blade (Mastel Precision; Figure 15-4) or 15-degree metal blade is used to enter the sclera at one of the marked sites. For the first site, I penetrate but do not completely perforate through the sclera, while for the second site I barely enter the sclera. This allows the use of a sharp needle to enter the eye directly below the IOL complex as described below (Figures 15-5 and 15-6).