18.1 Introduction

For routine cataract cases, the ideal location for intraocular lens (IOL) insertion is into the same place as the original human crystalline lens—within the capsular bag. In most eyes, the capsular bag provides a secure positioning of the IOL with good long-term stability. However, placement of an IOL in the ciliary sulcus is preferred in some cases with a compromise of the posterior capsule or weakness of the zonules.

The ciliary sulcus, as the name implies, is a small space between the posterior surface of the iris base and the anterior surface of the ciliary body. The diameter of the sulcus depends on the eye, but it is typically ~ 12-13 mm wide. The sulcus can effectively fixate an appropriately designed IOL with good long-term stability and safety. The most common conditions where a sulcus IOL is preferred are rupture of the posterior capsule, zonular laxity, and planned piggyback IOL placement (Fig. 18.1). This chapter introduces some basic concepts on sulcus IOL implantation. These concepts are expanded upon in subsequent chapters in Section V: Primary IOL Implantation with Compromised Capsules.

18.2 IOL Design and Materials

The most commonly used IOLs in the United States are single-piece acrylic designs, where the haptics and optic are cut or molded from the same material (see Chapter 2). This results in haptics that are resistant to deformation and that require smaller incisions for insertion. But these single-piece acrylic IOLs tend to have haptics that are thick with square edges, which makes them unsuitable for placement in the ciliary sulcus. It is very important to avoid placing a single-piece acrylic IOL into the sulcus because it is likely to become decentered, scrape the back of the iris, and induce uveitis-glaucoma-hyphema syndrome (Fig. 18.1).s. Literatur ^{,​ 2}

The most appropriate IOLs for the ciliary sulcus are ones that are specifically designed for that purpose. These IOLs have a slightly larger overall size for a better fit within the sulcus, haptics with architecture that helps to secure them in place, and an angulation so that the optic is kept away from the posterior surface of the iris. In the United States, the IOLs that are most commonly placed in the ciliary sulcus are not Food and Drug Administration (FDA) approved for that indication and are used off-label for this placement. These lenses are typically three-piece designs with fine, thin haptics, and an angulation of a few degrees to keep the optic away from the iris. The optic material can be acrylic or silicone, though some surgeons prefer a silicone IOL with a rounded edge in case there is contact with the posterior iris. Note that a peripheral iridotomy is not typically needed with sulcus IOL placement; there is adequate flow of aqueous through the pupil because it is not blocked by the optic. ^{1 ,​ 2}

Given that the ciliary sulcus is more anterior than the capsular bag, the effective lens position is different; therefore, IOL calculations must be modified to produce the intended refractive results. If the IOL is placed entirely within the ciliary sulcus, it will sit ~ 0.5 mm more anterior than if it is placed within the capsular bag. This means that the IOL power must be reduced to provide the same refractive outcome. For most eyes, this means reducing the IOL power by ~ 1 diopter (D) for an average eye. For larger, myopic eyes the IOL needs to be reduced by ≤ 0.5 D, and for small, hyperopic eyes, it may need to be reduced by 1.5 D. The exact adjustment to the IOL power can be calculated if the sulcus position is known; however, a simple “rule of 9s” method is a reasonable approximation (Table 18-1).

If the anterior capsular rim is intact and there is a centered and appropriately sized capsulorhexis, there is another option for placement: the haptics can be placed in the ciliary sulcus, and then the optic can be pushed posteriorly and captured behind the capsulorhexis. This gives excellent long-term stability and has a minimal effect on the lens power calculations because the optic itself is actually considered to be in the bag, whereas the haptics are in the sulcus (Fig. 18.2). This technique is also useful if there is laxity to the zonules, such as in cases of advanced pseudoexfoliation. Other variations of sulcus IOL placement, including optic capture, reverse optic capture, and use of either the anterior or posterior capsule have been described by Gimbel and DeBroff. ³ This is covered more completely in Chapter 19.