TECHNIQUES FOR SULCUS FIXATION OF SINGLE-PIECE ACRYLATE IOLS

Kenneth J. Rosenthal, MD, FACS and Nandini Venkateswaran, MD

Most, if not all, intraocular lenses (IOLs) available in the United States are labeled by the US Food and Drug Administration for implantation wholly within the capsular bag in adults. Aside from polymethylmethacrylate (PMMA) IOLs designed for anterior chamber placement, there are no on-label options for placement of an IOL where the capsular bag is deficient or absent. Techniques have evolved for placement of 3-piece IOLs in the posterior chamber using methods other than in-the-bag fixation. Examples of these are discussed elsewhere in this book and include iris fixation, sulcus fixation by transscleral suture, and intrascleral direct haptic fixation. While 3-piece IOLs are generally well tolerated in the sulcus, they are still associated with a relatively high incidence of partial or complete dislocation. One reason is that the hapticto-haptic diameter of posterior chamber IOLs (PCIOLs) designed for compression within the capsular bag are shorter that the diameter of the ciliary sulcus (scleral spur to scleral spur). Alternatively, the PCIOL may subluxated through a large central posterior capsule opening or a significant zonular dehiscence.

Problematically for nonintracapsular fixation is the fact that the most popular PCIOLs are of the single-piece acrylate design (both hydrophobic and hydrophilic). These include almost all toric and multifocal IOLs and all extended depth of focus IOLs approved in the United States.

In this chapter, we will describe the technique and rationale for fixation of single-piece acrylate IOLs in the absence of capsular bag support; these techniques now make it possible to implant advanced technology IOLs when intracapsular bag fixation cannot be employed.

Controversy

Placement of single-piece IOLs in the ciliary sulcus in instances of compromised capsular support has historically been discouraged. Several studies have shown that these lenses, once in the ciliary sulcus, can become unstable, decenter, and ultimately lead to chafing of the posterior aspect of the iris. This may cause recurrent iridocyclitis, transillumination defects, secondary intraocular pressure (IOP) elevation, pigment dispersion glaucoma, intraocular hemorrhages, and cystoid macular edema (Figure 36-1).^1–6 The larger and thicker sized haptics, planar shape of the optic, and the overall shorter diameter of single-piece IOLs can all contribute to posterior chafing of the iris and lens decentration.⁷ Therefore, the conventional advice is to avoid placing single-piece lenses in the ciliary sulcus.

It is worth noting that there may be differences in the biocompatibility of hydrophilic vs hydrophobic acrylate IOLs. Rather than a smooth surface, the latter have a more textured finish, which can contribute to iris chafing. In addition, the sharp square edges of the optic may cause chafing if there is IOL tilt, as is often the case with unsupported sulcus IOLs of any type.⁸ Our experience overall is that IOLs that were designed for placement in the capsular bag frequently do not fare well in the sulcus. In the 1970s and 1980s when sulcus fixation was the norm, the haptic-to-haptic diameter was significantly larger, taking into account the larger diameter of the sulcus vs that of the capsular bag. However, these lenses now have a shorter haptic-to-haptic diameter that may be too short for sulcus fixation. As a result, these capsular bag IOLs may decenter or chafe the posterior iris causing transillumination defects and chronic inflammation, hyphema, and increased IOP. UGH syndrome refers to this constellation of uveitis, glaucoma and hyphema.9

It should parenthetically be noted that placing a single-piece IOL within the capsular bag can occasionally be associated with chafing complications. For example, we recently reported a combined phacotrabeculectomy case¹⁰ with significant transillumination defects that closely resembled the position and shape of the optic and haptics of a single-piece IOL that had been placed in the capsular bag (Figure 36-2). We postulate that despite proper anatomic positioning of the IOL in the capsular bag, postoperative hypotony and forward displacement of the iris-lens diaphragm caused posterior iris chafing and development of transillumination defects.

Some authors suggest that single-piece IOLs should never be placed in the sulcus. However, other studies have suggested that single-piece IOLs can be tolerated in the ciliary sulcus without development of inflammatory complications.⁹ Further examination of this issue shows that the problems associated with sulcus placement are specifically attributable to chafing—the apposition of and friction between the anterior IOL surface and the posterior iris.

In the landscape of modern IOL implant technology, premium single-piece IOLs, namely toric, multifocal, and extended depth of focus, are being used routinely to achieve desired visual results. However, in cases of inadequate capsular support, there has been an unmet need for techniques to permit safe and effective use of these lenses. Alternative methods of IOL fixation, such as direct iris suture fixation of 3-piece IOLs, may be proinflammatory, causing unintended sequelae such as chronic cystoid macular edema.11 Interestingly, however, a technique one of us (KJR) developed, in which a 3-piece IOL may be sutured to the anterior iris, causes few if any problems.

In this chapter, we aim to describe novel techniques developed by or used by one of the authors (KJR) to allow for implementation of single-piece IOLs. These techniques expand the anterior segment surgeon’s options for sulcus IOL fixation, facilitate use of advanced technology IOLs (toric, multifocal, toric multifocal, and extended depth of focus) that are not available in a 3-piece design, as well as in a whole host of challenging surgical cases without adequate capsular support, while reducing the risk of postoperative complications. The techniques discussed include internal scleral fixation, intrascleral fixation with externalization of haptics, and optic capture techniques. Our findings have shown that these techniques are robust methods to implement single-piece IOLs in the ciliary sulcus in patients with compromised posterior capsular support.

Techniques

INTERNAL SCLERAL FIXATION OF SINGLE-PIECE POSTERIOR CHAMBER IOLS

With internal scleral fixation techniques, sutures are used to stabilize and attach the haptics of single-piece PCIOLs to the internal scleral wall at the level of the ciliary sulcus. This is intended to immobilize the IOL and keep it posterior enough to prevent contact with the iris.¹² There are 3 variations of this technique.

Through the Loop Fixation

The enVista IOL (Bausch + Lomb) is a single-piece aspheric, hydrophobic, acrylic IOL with a strut between the haptic and the optic, forming an encircled opening on the proximal aspect of each haptic. We pass a polytetrafluoroethylene CV-8 (ePTFE; Gore-Tex; WL Gore & Associates) or 9-0 polypropylene suture through this opening. A 180-degree marker is used externally to identify positions for ideal placement of sutures from each haptic. A partial-thickness scleral flap or a scleral groove starting 2 mm posterior to the limbus is fashioned at each of these locations. The suture needles can be passed ab interno through the sulcus so that it exits at the limbus on either side of the IOL haptics at the base of the groove or beneath the flap. The suture tension is adjusted so the IOL is well centered before tying it down to the scleral wall. Care must be taken to avoid overtightening the sutures to the point of inducing corneal astigmatism. Optionally, the knot can be rotated so that it is tucked within the adjacent sclera.

Through the Haptic Suture Fixation

In this original technique, both long tapered needles of a double-armed 9-0 polypropylene suture are used to pierce the tip of one haptic. Care must be taken to place the needle through the center of the haptic thickness, to avoid tearing the soft acrylic material. We have found that the ideal double-armed placement of this suture is approximately one-third of the way between the haptic-optic junction and the haptic tip (closer to the optic). Since the haptic is thicker along its anterior surface than along the anteroposterior (parallel to the IOL plane) surface, we have found that passing the needle from anterior to posterior allows a more secure fixation to the haptic. The same suture preplacement is performed for the opposite haptic. The needles can then be passed using the same technique described previously to exit at the limbus on either side of each IOL haptic, and the suture can be tied down to the scleral wall once the IOL is positioned in the ciliary sulcus. Again, attention should be focused on fixating the IOL posteriorly enough to ensure that there is no contact with the iris. Excessive fixation suture tension may decenter the IOL and must be avoided.

Case 1 (Figure 36-3). Our first use of this technique was in a 35-year-old woman with congenital rubella syndrome: microcornea, aniridia, cataract, and advanced glaucoma that was well controlled on topical medication. This patient had surgery for her congenital cataract at 2 years. Despite limited visual potential, she desired a cosmetic improvement as well as a realistic optimization of her vision. One of us (KJR) placed a HumanOptics Artificial Iris under a compassionate use exemption along with a single-piece acrylate IOL (Tecnis Monofocal; Johnson & Johnson Vision). After preparation of scleral grooves, a 9-0 polypropylene suture was preplaced through the proximal portion of each haptic in double-armed fashion. These sutures were passed through a 3.0-mm incision, exiting under the scleral groove. The IOL was inserted and centered, and the proximal haptic’s sutures were passed through the proximal scleral groove. A similar technique was used to secure the artificial iris, after trephining it to the appropriate size. The patient achieved satisfactory cosmetic improvement and a modest improvement in her visual acuity.

This first case demonstrated the reliability of suturing through the haptic, but the presence of an interposed artificial iris and the absence of central iris tissue did not address the issue of safety in a patient with an intact iris. The technique needed to be proven in a patient with more normal anatomy and an intact iris.

Case 2. A 56-year-old man was referred for cataract surgery. He gave a history of penetrating injury decades earlier from a sharp object. He had a corneal scar with 5 diopters of corneal astigmatism. Potential acuity meter testing revealed 20/40 predicted postoperative acuity. The patient underwent cataract surgery with insertion of an acrylic toric IOL (Tecnis Toric; Johnson & Johnson Vision). One week postoperatively, the patient noted pain and decreased vision. Endophthalmitis was diagnosed, and the vitreoretinal consultant surgeon decided to explant the IOL while performing a therapeutic vitrectomy and injection of antibiotics. Prior to this intervention, a discussion about the postoperative rehabilitation of the patient determined that no clear path existed because a toric IOL would be the only way to correct the large amount of astigmatism, but it was deemed that saving the eye took precedence.

Stay updated, free articles. Join our Telegram channel

Join