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Challenging cases may necessitate placement of IOL in ciliary sulcus
Avoiding vitreous prolapse is key to lens placement in the sulcus.
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For routine cataract cases, we like to insert our new IOL into the same place as the original human crystalline lens — into the capsular bag. In most eyes, the capsular bag provides a secure positioning of the IOL with good long-term stability. But in some cases with a compromise of the posterior capsule or weakness of the zonules, placement of an IOL in the ciliary sulcus is preferred.
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 about 12 mm wide. The sulcus can effectively fixate an appropriately designed IOL with good long-term stability and safety. The most common conditions in which a sulcus IOL is preferred include rupture of the posterior capsule, zonular laxity and piggyback placement.
IOL design and materials
The most commonly used IOLs in the U.S. are single-piece acrylic designs in which the haptics and optic are cut or molded from the same material. This gives us haptics that are resistant to deformation and allows us to insert these IOLs through smaller incisions. But these single-piece acrylic IOLs tend to have haptics that are thick with square edges, and that makes them unsuitable for placement in the ciliary sulcus. It is 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 (Figure 1).
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 U.S., the IOLs that we most commonly place in the ciliary sulcus are not approved by the U.S. Food and Drug Administration for that indication, and we use them in an off-label manner. These lenses are typically three-piece IOLs 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, although some surgeons prefer a silicone IOL with a rounded edge in case there is contact with the posterior iris. A peripheral iridotomy is not typically needed with sulcus IOL placement because there is adequate flow of aqueous through the pupil because it is not blocked by the optic.
Because the ciliary sulcus is more anterior than the capsular bag, the effective lens position is different, and therefore the IOL calculations must be modified to produce the intended refractive results. If the IOL is placed entirely within the ciliary sulcus, it will sit approximately 0.5 mm more anterior than if it were 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 about 1 D for an average eye. For larger myopic eyes, the IOL needs to be reduced by 0.5 D or less, and for smaller hyperopic eyes, it may need to be reduced by 1.5 D.
Figure 1. This single-piece acrylic IOL was placed in the ciliary sulcus, which resulted in complications. The IOL has a “sunset” appearance because it has become decentered inferiorly (green arrow), and the sharp edges of the haptics have scraped the pigment from the posterior iris, causing transillumination defects (blue arrows), uveitis, glaucoma and micro-hyphema. This lens had to be removed and replaced with a three-piece IOL.
Figure 2. This patient has a central defect of the posterior capsule, which precluded placement of the IOL within the capsular bag. Instead the three-piece lens was placed with the haptics in the sulcus, and then the optic was captured behind the anterior capsular rim. This gives excellent long-term stability and has minimal effect on the lens power calculations because the optic itself is actually considered to be in-the-bag while the haptics are in the sulcus.
Images:Devgan U
If the anterior capsular rim is intact and there is a centered and appropriately sized capsulorrhexis, 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 capsulorrhexis. This gives excellent long-term stability and has minimal effect on the lens power calculations because the optic itself is actually considered to be in-the-bag while the haptics are in the sulcus (Figure 2). This technique is also useful if there is laxity to the zonules, such as in cases of advanced pseudoexfoliation.
Insertion of sulcus IOL with posterior capsule rupture
With a ruptured posterior capsule, placement of the IOL within the capsular bag can be difficult or impossible. A small central rupture could still give adequate support for in-the-bag IOL placement, whereas a larger posterior capsule defect will not. And the small central capsular breaks can extend due to the forces placed on the tissues during IOL insertion, and this could lead to a larger defect. Placing the entire three-piece IOL in the sulcus can be accomplished with a large rupture of the posterior capsule and even if there is a radialization of the capsulorrhexis and compromise of part of the anterior capsular rim.
The key for sulcus IOL placement is to avoid vitreous prolapse. This can be accomplished by using a dispersive viscoelastic to compartmentalize the eye. Placing a bolus of dispersive viscoelastic through the posterior capsular break will tamponade the vitreous and create a barrier. The IOL should then be placed gently into the sulcus. Miotic agents can be instilled to constrict the pupil to aid in IOL stability. If the capsulorrhexis is intact and is of appropriate dimensions, the optic can be captured through it like a buttonhole. This will create an excellent barrier and give better stability than placing the IOL entirely within the sulcus. In either case, care should be taken when removing viscoelastic from the anterior chamber with a sulcus IOL in the eye. A gentle approach should be used with the understanding that it is better to leave a little viscoelastic within the eye than to risk vitreous prolapse. The postoperative transient pressure spikes from the retained viscoelastic can be managed with topical agents and oral acetazolamide.
In certain challenging cases, the IOL cannot be securely placed within the capsular bag, and alternative positioning and fixation are required. Placement of a sulcus IOL can be useful in these cases, with or without optic capture through the anterior capsular rim, and it can provide an excellent visual outcome for our patients.