Gabor B. Scharioth, MD, PhD
An ophthalmic surgeon could be faced with 3 main scenarios where intrascleral haptic fixation is warranted. The patient could be aphakic after complicated phacoemulsification, trauma, vitreoretinal surgery, or intracapsular cataract extraction. Second, the patient could be pseudophakic with a dislocated intraocular lens (IOL) or even dislocated capsular bag-IOL complex, sometimes with a capsular tension ring in place (Figure 38-1). This may be even more complicated if previous secondary implantation with intraocular (transiridal or transscleral) suturing was performed. Third, the vitreoretinal surgeon could recognize IOL dislocation during surgery, whether preexisting or caused by the surgeon him- or herself, thereby complicating the surgery and requiring intraoperative repair (Figure 38-2). Fixation of IOLs in the case of insufficient or no capsular support is challenging and requires a large armamentarium of techniques to solve different situations.1–22
Since the introduction of IOLs in cataract surgery by Sir Harold Ridley, this became the standard of care in the late 1980s. Whenever possible, in-the-bag implantation with overlapping continuous curvilinear capsulorrhexis is preferable. However, various IOL models, fixation sites, and techniques are recommended for difficult situations.
Anterior chamber lenses were used for many years because of the relatively easy implantation technique even in the total absence of capsular support. However, fixation in the anterior chamber angle may cause glaucoma and chronic irritation to the iris. Furthermore, long-term endothelial cell loss with corneal decompensation is reported for angle-fixated IOLs as well as for iris claw lenses fixed to the anterior surface, a technique introduced by Jan Worst almost 30 years ago. Both require relatively large incisions up to 6.5 mm. For iris claw lenses, uveitis-glaucoma-hyphema syndrome has been reported, and late dislocations may occur. For iris claw lenses, we recommend the retropupillary implantation technique.21 This is superior because it prevents contact with the corneal endothelium intraoperatively (eg, during fluid-air exchange during a pars plana vitrectomy) and postoperatively due to eye rubbing, blinking, etc.
Iris-fixated IOLs tend to experience IOL wobbling with optical side effects and unstable vision. Some surgeons prefer iris-sutured IOLs. However, this can cause pupil ovalization and iris chafing with uveitis and/or pigment dispersion and secondary complications like chronic inflammation and secondary glaucoma. Also, these techniques need sufficient iris stroma for fixation and cannot be used in aniridic patients.
We are convinced that the best place for fixation of IOLs in the absence of sufficient zonular/capsular support is the sclera. It is the strongest intraocular tissue, mostly avascular, and does not tend to inflammation. Vitreoretinal surgeons have known for decades that implants and explants for retinal procedures are well tolerated over a long period of time. In moderately damaged zonular apparatus cases, we have used capsular bag refixation techniques with modified capsular tension rings (eg, Cionni ring) or Ahmed segments (both Morcher GmbH) for many years. These implants are positioned in the capsular bag and have an extra eyelet that is positioned on the anterior surface of the anterior capsule and fixed with a 10-0 or 9-0 Prolene (Ethicon) suture transsclerally into the ciliary sulcus. This technique is difficult and needs an intact capsulorrhexis. Furthermore, cortical clean-up is less complete. This tends to cause early secondary cataract and capsular fibrosis with rhexis phimosis. For more severe luxated capsular bags or for fixation of IOLs in the absence of sufficient support, the haptic of the IOL could be knotted to a 10-0 or 9-0 Prolene suture and fixed to the scleral wall. Many variations of transscleral suture fixation are reported, and these techniques are used worldwide because small-incision techniques can be used, the IOL position in the posterior chamber is more physiologic, and standard lenses could be used. In the case of a dislocated IOL, this could be refixated by intraoperative haptic externalization for knot fixation to the haptic and transscleral suture fixation without need for IOL explantation.
A fibrosed capsular bag, especially with a capsular tension ring in place, can easily be refixated with double-armed 10-0 or 9-0 Prolene suture to the ciliary sulcus. The first needle is passed through the capsule catching the haptic and/or capsular tension ring and passed through the sclera while the second needle is just placed above the bag through the sclera. The so-created suture loop will hold the bag after knotting to the sclera. Usually more then one suture is necessary to stabilize the whole bag. Recently, Hoffmann et al reported a technique for transscleral suture fixation without opening of conjunctiva.22 Here the pockets for suture knots are prepared from the limbus into the sclera, a double-armed suture is used and stitched 1.5 mm from the limbus through the scleral pockets and conjunctiva, needles are cut off, and the sutures are retrieved from the pocket with a hook. The suture is tied and the ends buried into the scleral pocket.
However, centration of suture-fixated IOLs is difficult, and lens tilt is a common problem. This will result in internal astigmatism and inconvenient refractive outcome. Fixation into the ciliary sulcus without capsular and zonular support is difficult, and malpositioning may result in chronic irritation to the ciliary body and/or iris with secondary complications. Good long-term stability is reported, but late dislocations due to suture biodegradation may occur and require reinterventions.23–27 There is a long learning curve for suture fixation techniques, and outcome is very much dependent on surgeon experience. Furthermore, there could be a need for special IOLs, which may not be readily available.
For these reasons, we were searching for a technique for IOL fixation in the absence of sufficient capsular support using a standard foldable IOL and scleral fixation, independent of iris changes, independent of the amount of zonular/capsular damage, sutureless, minimizing contact to uveal tissue, and capable of standardization.
In 2006, we performed the first intrascleral haptic fixation of a standard 3-piece IOL.28
This sutureless technique for fixation of a posterior chamber IOL (PCIOL) uses permanent incarceration of the haptics in a scleral tunnel parallel to the limbus. After peritomy, the eye is stabilized either by pars plana infusion (ie, 25 gauge) or by anterior chamber maintainer (Figure 38-3). We try to prevent any diathermy of episcleral vessels to reduce the risk for scleral atrophy. Two straight sclerotomies ab externo are prepared with a sharp 23-gauge cannula or 23-gauge microvitreoretinal blade about 1.5 mm behind the limbus exactly 180 degrees from each other and directed toward the center of the globe (Figures 38-4 and 38-5). New cannulas are used to create a limbus-parallel tunnel at about 50% of scleral thickness, starting from inside the ciliary sulcus sclerotomies and ending with externalization of the cannula after 2.0 to 3.0 mm (Figures 38-6 and 38-7). A standard 3-piece IOL with a haptic design fitting to the diameter of ciliary sulcus is implanted with an injector, and the trailing haptic is fixated in the corneal incision (Figures 38-8 and 38-9). The leading haptic is then grasped at its tip with special straight 25-gauge forceps (Scharioth IOL fixation forceps 1286.SFD; DORC International) pulled through the sclerotomy and left externalized (Figures 38-10 through 38-13).