The recorded history of IOLs begins more than 200 years ago. Since Harold Ridley's first successful implantation,1 IOLs have evolved to the sixth generation and include foldable models and rigid designs, materials, and constructions. The Ridley implant had a late dislocation rate of 10%. Today—despite the improved small-incision techniques with the wide use of foldable lOLs—a dramatic increase in IOL decentration and tilt is noted.2,3 IOL malposition was a contributing factor in 60% of posterior chamber IOL explanations.4
Sometimes, the surgeon must decide whether to reposition, explant, or exchange a dislocated lens. In eyes complicated with loss of capsular integrity, zonular weakness and capsular contraction syndrome due to trauma; pseudoexfoliation; glaucoma or high myopia lens decentration; and dislocation were more frequently observed.5,6
Most IOL subluxation cases may be treated with reassurance and miotic agents,7 and a limbal approach may be used to manage subluxed posterior chamber IOLs.8 A pars plana surgical technique has been used for more severe subluxations and dislocations.9 Several surgical options are available to manage posterior chamber IOL malposition, including IOL exchange, suturing the haptics to the iris, ciliary sulcus,10-12 pars plana;13 rotating the IOL haptics into the ciliary sulcus; inducing pupillary capture, or rotating the entire posterior-chamber IOL into the anterior chamber.14 Some ophthalmologists recommend a nonsurgical approach, because the IOL is difficult and hazardous to reposition, and the dislocated IOL may be well tolerated—although optically useless.15
The three-piece flexible IOL design is probably the most common IOL model, now being gradually replaced by monoblock lenses. Recently, however, there has been a (1) dramatic increase in popularity of bimanual microinsicion cataract surgery and (2) renaissance of plate-haptic IOL designs (eg, ThinOptX [ThinOptX, Abingdon, Virginia] and Acri.Smart [Acri.Tec, Henningsdorf, Germany]). Therefore, the management of a plate-haptic IOL displacement may still be a problem in the near future.
Several foldable IOLs appear more prone to optic or haptic damage than others.2 Compared with silicone or acrylic IOLs, collamer lenses are one of the most difficult to manipulate within the eye during IOL repositioning and suture fixation. Foldable IOLs lack the easily grasped open-loop haptics, and their mechanical properties are slippery, flexible, and have a low resistance to physical stress. Most surgeons, therefore, prefer to explant these lenses and replace them with new lOLs.16
Clearly, repositioning and new fixation of the dislocated flexible plate-haptic posterior chamber lOL needs a special approach, unlike other designed rigid and soft IOLs. Few techniques have been implicated in the fixation of dislocated plate-haptic silicone IOLs,16-18 however, they are not universally suitable in all cases. For instance, suturing the plate-haptic IOL to the iris17 is not indicated in the following cases: if the iris pigment epithelium is dispersed; big iris coloboma; pseudoexfoliative syndrome; iris atrophy; and glaucoma. Furthermore, the risk of IOL damage is very high by using such a technique.
It seems to us that repositioning the dislocated plate-haptic IOL into the ciliary sulcus without suturing18 cannot provide an adequate fixation, even in the presence of sufficient posterior capsular support. The transscleral fixation technique of a dislocated silicone plate-haptic IOL via the pars plana16 has some drawbacks. First, pulling the IOL at the haptics hole, to place it into the sulcus may damage the lens. Second, the standard three-port vitrectomy is imperative, so it cannot be recommended with mild IOL malposition, as the vitrectomy is unnecessary.
During the last 11 years, 8,730 single-piece plate-haptic IOLs were implanted in our clinic. Before the advent of the two-string technique, among the surgical options to manage malposition of these IOLs, their exchange was the most popular in the majority of cases. Herein, we present our technique of the plate- haptic posterior chamber IOL repositioning and suturing to the ciliary sulcus.
We studied 14 eyes of 14 patients who received a plate-haptic foldable collamer posterior chamber IOL (RSP-1 and RSP-2 models, manufactured in S. Fyodorov Eye Microsurgery Complex, Moscow, Russia). The IOL included a single fenestration on each end of the plate haptic (Figure 1). Five patients experienced posterior IOL dislocation, two of which were lying on the retina. Nine eyes had stages of sunrise or sunset syndrome and IOL tilt (Figure 2). Most patients (n=7) had a history of blunt ocular or head trauma. In one case, dislocation followed the Nd:YAG laser capsulotomy.
Preoperative findings included pseudoexfoliation syndrome, capsular phimosis of different degree, angle recession, open-angle glaucoma, high myopia, iris transillumination defects, and vitreous hemorrhage. Preoperative BCVA ranged from 0.01 to 0.90. I performed transscleral suture fixation with the two-string technique in all cases.
SURGICAL TECHNIQUE
Transscleral fixation followed the scheme depicted in Figure 3. Four rectangle scleral flaps (at 10:30-, 1:30-, 4:30-, and 7:30-o'clock) were created 1 mm from the limbus. Next, corneal paracenthesis were made at the projection of each scleral flap, and the anterior chamber was filled with viscoelastic. If the dislocated IOL sank into the vitreous gel, a standard three-port pars plana vitrectomy was performed.
If the IOL was located on the retina, we replaced one eyelet to the physiological excavation of optic nerve disc. A hook was then used to hold the haptic through its positioning hole (Figure 4). The implant was lifted to the iris plane, and the light pick was removed and exchanged for a spatula to pull the dislocated IOL into the anterior chamber and onto the iris. The 10:30-o'clock scleral flap was reflected back onto the cornea, and a double-armed 10-0 polypropylene suture on a curved needle was fixed to its bed. Entering the globe 1.0 mm to 1.5 mm posterior to the surgical limbus, the needle was advanced from behind the iris, toward the IOL haptic, and partially passed through its eyelet (Figure 5). A bent 25-gauge needle was introduced into the anterior chamber through the scleral bed on the opposite side (ie, 1:30-o'clock), and the curved needle was engaged into its lumen in front of the lens haptic. Both were withdrawn through the wound. Corneal paracenthesis on each side facilitated the curved needle delivery—through the guiding needle (Figures 6 and 7).
The above-mentioned maneuvers were repeated, this time on the opposite site (ie, 4:30-o'clock) to begin the second haptic suturing to the first point of fixation (ie, 10:30-o'clock). This provided the mirror reflection manner of the suture path of the upper fixated haptic. The sutured IOL was positioned into the pupil, viscoelastic removed, and the sutures were tied and buried under the scleral flap.
In all cases, the IOLs were well positioned and stable. One patient had a slight IOL decentration, and two had a mild IOL tilt that did not influence postoperative outcomes and were not an indication for additional surgical interference. Postoperative complications included corneal edema, temporary elevation of intraocular pressure, and mild vitreous hemorrhage. All complications were managed successfully. BCVA at the last follow-up examination (6 months to 10 months) ranged from 0.70 to 0.90 in all but three eyes with coexisting fundus lesions.
In our method, using four IOL fixation points (ie, 10:30-, 1:30-, 4:30-, and 7:30-o'clock) avoided damage to the long posterior ciliary arteries. Complications were few, did not threaten sight, and were resolved with appropriate treatment. In three patients with postop intraocular pressure elevation, two had a history of open-angle glaucoma. Two eyes had mild vitreous hemorrhage, however, they had a history of blunt ocular trauma.
We believe that the two-string technique is a simplified plate-haptic posterior chamber IOL repositioning procedure, whereby positioning a dislocated IOL into the anterior chamber makes its manipulation much easier than if it is in the posterior eye segment. This is especially true in patients with narrow and rigid pupils. Furthermore, there was no need for perfluorocarbon liquid or any specially designed instruments or devices.
The management of the patients described in this article is a challenging feat, with a high potential risk of postoperative complications. Our long-term results were stable, and therefore, we recommend the two-string technique for clinical use in cases of single-piece plate-haptic IOL decentration and dislocation.
Boris Malyugin, MD, PhD, is Chief of the Department of Cataract and Implant Surgery, and practices at the S. Fyodorov Eye Microsurgery Complex State Institution, in Moscow, Russia. He is a member of the CRST Europe Editorial Board. Dr. Malyugin states that he has no financial interest in the companies or products mentioned. He may be reached at malyugin@online.ru.
Up Front | Mar 2007
The Two-String Technique
This strategy is a solution for dislocated posterior chamber plate-haptic lenses.
Boris Malyugin, MD, PhD
