Kevin M. Miller, MD
Overview
This chapter will describe my approach to passive fixation of a posterior chamber intraocular lens (PCIOL) in the ciliary sulcus in the absence of sufficient support for capsular bag implantation. It will assume there is good zonular support for the remnant peripheral capsular bag. This chapter will not describe techniques that involve fixating the lens to the iris or sclera. For details regarding these other methods of fixation, please refer to the other chapters in this textbook.
Two Scenarios
Two common scenarios describe most instances where passive fixation of a PCIOL in the ciliary sulcus might be necessary. The first is the unanticipated posterior capsule rupture that develops during otherwise routine surgery, including surgery performed under complex circumstances. The second occurs either when a reoperation is performed on an eye with a known posterior capsule defect or when surgery is performed on an eye for which a posterior capsulotomy is planned. Two examples of the latter include infant eyes with cataracts and post-vitrectomy eyes with dense central posterior capsule plaques. Obviously, there is more time for preoperative surgical planning in the second scenario. The surgeon has to respond to the capsule rupture in the first scenario on the fly.
General Considerations
The cataract surgeon should always be prepared for the possibility of posterior capsule rupture. He or she should always have a back-up, sulcus-appropriate, PCIOL available for each eye undergoing surgery on a given day. The surgeon should know how to use the back-up lens before it becomes necessary. The absolute worst time to experiment with a seldom-used IOL is in the heat of the moment when the heart is racing and untoward things have already happened inside the eye. It is my practice to order a lens that is appropriate for the capsular bag and a different lens that is appropriate for the sulcus for every eye. I email a spreadsheet containing my list of lenses to the operating room at least a week in advance. The operating room confirms that all ordered lenses are available well in advance of my surgery day and they immediately order any lenses that are missing from our consignment. Our operating room also carries a wide range of anterior chamber IOLs in the unlikely event they might be needed. If I think there is a reasonable possibility I will need an anterior chamber IOL, I specifically order that lens in a range of haptic sizes. Our operating room staff do not bring my back-up sulcus lenses into the operating room. Rather, they leave them in the implant room and we call for them as needed. We do this because frequent handling of the boxes containing back-up lenses that are not used destroys the boxes and risks the sterility of the lenses. It is important for operating room staff who are responsible for ordering lenses not to become complacent with checking the availability of back-up lenses simply because they are not used very often.
Figure 18-1. The discontinued Staar Surgical AQ2010V silicone PCIOL, sitting inside its injector cartridge, is shown. It was the last lens in the United States to have a fully round optic edge.
Figure 18-2. The author’s current preferred back-up sulcus lens, sitting inside its injector cartridge, is shown. It is the Staar Surgical CQ2015A, which is a 3-piece PCIOL with a Collamer optic and polyimide haptics. The optic has a round anterior edge and a square posterior edge.
It is important for surgeons to know the features of an appropriate back-up lens for ciliary sulcus implantation. Current-generation single-piece acrylic and plate-haptic lenses should never be implanted in the sulcus.1 Most surgeons, without thinking much about it, choose a 3-piece design with a 6-mm square-edge optic and posteriorly angulated, 13-mm haptics. They get away with this lens most of the time, especially if they can capture the optic posterior to the capsulorrhexis. Occasionally, however, they find, usually a few years later, that this default lens causes uveitis-glaucoma-hyphema syndrome. Unfortunately, no lens currently manufactured in the United States is specifically designed for the ciliary sulcus. All of us place lenses in the sulcus that were designed for the capsular bag. An appropriate lens design would include a relatively large optic diameter, say 7 to 7.5 mm, with rounded edges and relatively large haptics.2 If it had a single-piece design, the haptics would also have round edges. In an ideal world, the haptic diameter would increase gradually as the optic power decreased. The ideal back-up lens would also have suture fixation eyelets on the haptics for use in the event of insufficient or completely absent peripheral capsular support.
In the absence of an ideal lens, the surgeon should choose the next best thing. In the United States, this used to be the Staar Surgical AQ2010V, which has a 13.5-mm haptic diameter (Figure 18-1). Unfortunately, this silicone lens was discontinued for financial reasons. A fair alternative is the Staar Surgical CQ2015A (Figure 18-2). This is a 3-piece, 6-mm optic Collamer lens with a round edge on the anterior surface and a square edge on the posterior surface. The 13-mm modified C loop haptics are made of polyimide and have 0-degree angulations.
The surgeon should be prepared to attempt a posterior capsulorrhexis if the initial capsule puncture is small and central. If the opening is large, the surgeon should be prepared to remove the posterior capsule flaps. They serve no real purpose and will simply be a bother to the patient postoperatively. The surgeon should also be ready to perform an anterior or pars plana vitrectomy. The necessary instrument sets and a vitrector should always be close at hand.
Intraoperative Assessment
Again, the first and most common scenario for sulcus fixation involves an unplanned posterior capsule rupture. Although beyond the scope of this chapter, all cataract surgeons should be familiar with the management of this problem. The moment a posterior capsule rupture is identified, it is important for the surgeon to stop aspirating, maintain infusion pressure, and inject a dispersive viscoelastic agent to maintain intraocular pressure (IOP) and barricade anterior migration of the vitreous prior to removing instruments such as phacoemulsification and irrigation/aspiration probes.
The surgeon should assess the size and location of capsular rent and the integrity of the zonules. As mentioned previously, if a small central tear can be turned into a posterior continuous curvilinear capsulorrhexis, that should be attempted. If successful, it might subsequently be possible to implant a lens inside the capsular bag.
If the posterior capsule is completely ruptured, the surgeon will need to assess the integrity of the zonules and anterior capsule. In the absence of a radialization from or to the anterior capsule or a problem with the zonules, it should be possible to implant an IOL in the ciliary sulcus. If the anterior capsulorrhexis is centered and not overly large, the optic can usually be captured behind the capsulorrhexis. If the capsulorrhexis is too small, it should probably be enlarged before the lens is implanted. The enlargement can be accomplished with scissors, capsulorrhexis forceps, or a vitrector.
When surgery is performed secondarily in an eye with a known posterior capsule defect, there is time for preoperative planning. I prefer to block these eyes with a posterior orbital injection. Surgery often requires more intraocular manipulation than would be comfortable under topical or topical/intracameral anesthesia. It is important to perform a good vitrectomy. This is often best done from the pars plana approach, and this approach is facilitated by a good orbital block.
Surgical Maneuvers
Once a decision has been made that sulcus fixation of a lens is appropriate based on adequate capsule and zonular support, and after the capsule and vitreous have been managed appropriately, it is time to implant the device.
Three-piece lenses require larger incisions than most single-piece lenses. I usually find it necessary to enlarge the incision, typically to 3 mm. Just prior, I fill the anterior chamber angle with a cohesive viscoelastic agent, such as Healon GV (Johnson & Johnson Vision). I try not to overfill the eye or inject material into the vitreous cavity. As a result, the eye will be soft during the lens injection. While I stabilize most eyes for lens injection using a second instrument that I place through the paracentesis incision, when I inject a 3-piece lens into a soft eye, I usually stabilize the eye by grabbing the roof of the incision with Colibri forceps.
The lens must be loaded into its injector. Each injector has its nuances and the surgeon should make a point of becoming familiar with them before the need arises. All of the major lens manufacturers have 3-piece models. As mentioned previously, my favorite sulcus model at this time is the Staar Surgical CQ2015A.
After enlarging the incision, I work the tip of the injector into the eye and inject the lens with the tip of the injector on the far side of the pupil. I make sure the leading haptic comes out of the injector pointing to the left. The injector can be rotated one way or the other as the lens is being injected to maintain this haptic orientation. It does not matter, for this purpose, which lens implant is used. The haptic should always come out pointing to the left. I like to open the entire lens in the anterior chamber and leave the trailing haptic outside of the eye. Once the lens is fully open and outside of the injector, I placed more cohesive viscoelastic into the anterior chamber on top of the optic. I then use a Kuglen or iris push-pull hook to manipulate the leading haptic just under the pupil and over top of the anterior capsule. It is critically important that the leading haptic not be placed into the vitreous cavity! Once the leading haptic is securely in the sulcus space, I tap the optic beneath the iris for 360 degrees, if necessary. Once the optic is beneath the pupil, I place the Kuglen hook into the haptic-optic junction of the trailing haptic and dial that haptic into the sulcus. There are a few tricks to performing the dial maneuver. In fact, 3 things must be done more or less simultaneously. First, the optic should be translated toward the opposite side of the eye from the haptic-optic junction. Then, while pushing the junction slightly posteriorly, the lens must be dialed clockwise to get the trailing haptic to pop beneath the pupil. Once the lens is completely in the ciliary sulcus, it can be centered in the pupil using the same Kuglen hook. It is usually best not to capture the optic behind the capsulorrhexis until after any viscoelastic material in the vitreous cavity has been removed.
It is critically important that these eyes not be allowed to become hypotonous from a wound leak after surgery. If a wound leak occurs, the optic may capture through the pupil. I often preplace a 10-0 nylon suture through the incision before removing the viscoelastic material.
When removing viscoelastic material from the anterior chamber, it is important to enter the eye with the irrigation/aspiration probe or infusion cannula at a very low bottle height or target IOP. The eye will often experience reverse pupillary block and the lens will retropulse toward the optic nerve. In rare cases, if the anterior chamber is pressurized too highly and too suddenly, the IOL may dislocate completely into the vitreous cavity. I like to enter with a target IOP of 20 mm Hg or a bottle height 10 to 20 cm above the eye.
Once the viscoelastic material has been removed from the anterior chamber, I like to go behind the optic with a vitrector to remove any that found its way into the vitreous cavity. At this point, I may capture the optic behind the capsulorrhexis if I feel it is appropriate. This is especially desirable if the IOL has a square anterior edge. If the lens is captured, the surgeon should be careful to inspect the appearance of the anterior capsule opening. If the minor axis on what will be a cat-eye opening is too small, it may be necessary to enlarge the anterior capsulotomy in the minor axis so as to avoid glare problems when the pupil dilates at night. If I am operating to resolve a negative dysphotopsia complaint by performing an IOL exchange, I usually avoid optic capture.
After closing the incision, I like to inject a miotic agent such as Miochol-E (acetylcholine chloride) into the anterior chamber. This brings the pupil down and ensures that the optic will not capture in the pupil during the early postoperative period.
Lens Power Adjustment
Whenever a lens is moved along the visual axis away from the fovea, whether inside or outside the eye, the increased vertex distance results in an effective increase in lens power. We see this phenomenon used to advantage by patients who wear aphakic spectacles. Rather than own a separate pair of reading glasses, many aphakic patients simply push their distance glasses down their noses to turn them into reading glasses. The same general thing happens when a 20-diopter (D) lens intended for the capsular bag is placed into the ciliary sulcus. Its effective power increases and the patient’s refractive outcome is more myopic than intended. All other things being equal, to compensate for a forward vertex change, surgeons should choose a sulcus lens that is slightly lower in power than the planned bag lens. For an eye of average axial length, this amounts to a decrease in power of 0.5 D, assuming the same A-constant or surgeon factor. If the A-constant changes, further adjustment to lens power will be necessary. For an eye with a short axial length, the adjustment might be a decrease of 1 D or more. Generally speaking, if the haptics are placed in the sulcus and the optic is captured behind the anterior capsulotomy, no change needs to be made in the lens power.
Postoperative Issues
Because vitreous gel is usually removed during these cases, it is important to treat postoperative inflammation aggressively. These eyes are prone to the development of cystoid macular edema. If a patient’s visual acuity does not reach the expected visual potential within a few weeks of surgery, the macula should be imaged for edema and membranes.
SIDEBAR 18-1
This series of clips from a surgical video shows the implantation of a Staar Surgical AQ2010V 3-piece silicone PCIOL. The lens was injected into the anterior chamber with its leading haptic oriented to the left (A). A Kuglen hook was used to manipulate the leading haptic under the pupil and into the ciliary sulcus (B). The same hook was used to engage the haptic-optic junction and dial the trailing haptic beneath the iris (C). Before entering the eye with an irrigation/aspiration probe to remove the viscoelastic material, the infusion pressure was reduced markedly to mitigate the effect of reverse pupillary block and lens retropulsion (D). The incision was thoroughly hydrated to make sure it did not leak postoperatively (E). If an incision is not secure, a 10-0 nylon suture should be added. Lastly, a miotic agent was injected to keep the optic posterior to the iris.
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