Scleral and Iris Sutured Posterior Chamber Intraocular Lenses and Intraocular Knot-Tying Techniques

27   Scleral and Iris Sutured Posterior Chamber Intraocular Lenses and Intraocular Knot-Tying Techniques

Gregory S.H. Ogawa

Scleral Sutured Posterior Chamber Intraocular Lenses

The origins of transscleral sutured posterior chamber intraocular lenses (PCIOLs) date back to the 1980s,1,2 and although it is currently performed with many different techniques, no gold-standard method has emerged. Just as several different factors affect a surgeon’s choice of intraocular lens (IOL) placement in the absence of capsular support, there are also numerous factors that influence the choice of technique for transscleral IOL suturing, such as the patient’s age, the availability of various suture material and needles, the patient’s clinical situation, and, perhaps equally important, the surgeon’s experience and level of comfort with the various techniques. We do not have high-level data from evidence-based medicine comparing different techniques, and there may be some level of inter-surgeon variation for the outcomes even with any particular technique. Despite there not being a gold-standard technique that is considered superior in all situations, transscleral sutured PCIOLs, as a category, are a useful part of the armamentarium for IOL fixation in the absence of capsule support.

Fundamental Principles

Regardless of the actual technique one uses for scleral suturing of PCIOLs, there are some core principles that may help surgeons optimize patient outcomes.

Eye Pressurization

Keeping the eye pressurized during the procedure has several advantages. It decreases the potential for intraocular bleeding associated with needle or blade passes through the sclera and ciliary body, and helps to minimize the tendency for suprachoroidal effusions or hemorrhages. A pressurized eye maintains its normal anatomic configuration, which makes it easier to properly position and secure the PCIOL. In most scleral sutured IOL situations, the lens capsule diaphragm is not intact, so an infusion source is needed to keep the eye pressurized. Most commonly that is achieved with a high-flow, self-retaining infusion cannula placed through a limbal paracentesis opening. If the procedure is done in conjunction with a retina specialist performing a pars plana vitrectomy, then the pars plana infusion cannula may be left in place for the sutured IOL portion of the procedure. The other side of the equation for maintaining pressure in the eye during surgery is to minimize fluid outflow. Perhaps the most important way to do this is to create self-sealing incisions. That principle should be applied to limbal paracentesis openings all the way up to 7-mm-wide scleral tunnel incisions that accommodate one-piece polymethylmethacrylate (PMMA) IOLs with eyelets on the haptics. Even though various incisions may require sutures to stabilize them prior to completion of the procedure, having corneal-valve incision architecture enables outflow to be controlled during the procedure even before any sutures are placed.

Vitreous Management

Appropriate removal of vitreous from the anterior chamber and the area well behind the iris significantly decreases the chance of causing intraoperative vitreous traction with the associated risk of retinal tears and retinal detachment. There can be episodes of fluid flow out of the eye during the procedure, and because vitreous “goes with the flow” of fluid, it is desirable to keep the vitreous well away from the incisions. Much of the work in these cases occurs behind the iris, so the vitreous needs to be removed more thoroughly, and further posteriorly, than is typically done for an unplanned capsule opening during cataract surgery. It is not uncommon to remove the vitreous from the anterior third (or more) of the vitreous cavity to decrease the risk of causing vitreous traction during the surgery as needles and instruments are passed through that space. The general guideline is to keep the vitrectomy cutting tip where the surgeon can see it, but passing it a little way out of view behind the iris with the port aimed posteriorly away from the iris, in the areas where sutures will pass, may be of benefit. It is common for anterior-segment surgeons to be rather uncomfortable guiding the port of the vitrectomy probe more than a couple millimeters behind the iris. One way to improve one’s comfort in working further behind the iris is to keep refocusing the microscope on the tip of the vitrectomy probe. As long as the probe is in focus, the surgeon can see anything that the probe could be getting close to, and the concern of getting too close to sensitive structures should decrease.

In a fairly well-sealed system, the vitreous goes to the port of the vitrectomy probe, regardless of where the probe enters the eye. One achieves a more posterior placement of the vitrectomy probe port immediately if the eye is entered through a pars plana incision, but the port on the probe can generally be maneuvered just as far posteriorly through a limbal paracentesis without needing to make the pars plana incisions that are less familiar to the anterior-segment surgeon. Some surgeons find it useful to inject ophthalmic intraocular triamcinolone acetonide suspension (Triesence, Alcon Laboratories, Fort Worth, TX) into the vitreous cavity to better visualize the vitreous needing to be removed. With unhurried, systematic movement of the vitrectomy probe through the desired areas, while focusing on the probe’s port to be able to see vitreous entering the port, the vitreous can often be removed just about as effectively without the steroid suspension.

Suture Positioning and Management

In several types of eye surgery, the need for, and emphasis on, sutures has significantly decreased over the past couple decades. For scleral sutured IOL cases, however, positioning, tying, and managing the sutures are central parts of a successful outcome. The sutures determine the position and stability of the IOL. Having a plan for exactly how the sutures will be positioned during all parts of the procedure, and then keeping track of the sutures and consistently managing them according to the plan is necessary for the procedure to go smoothly and to achieve a satisfying outcome. The precise details of suture positioning, tying, and managing vary depending on the technique that the surgeon selects.

Peripheral Iridectomies/Reverse Pupillary Block

When a PCIOL is sutured to the sclera, it creates a relatively firm plane behind the iris with the optic of the IOL almost always being larger than the postoperative pupil. The resulting situation is a uni-chamber eye where the iris can move easily with intraocular fluid movement, but the IOL moves only minimally. The iris can be pushed back against the IOL to create either intermittent or constant iris–IOL contact from a reverse pupillary block mechanism,3 analogous to that seen in conventional pigment dispersions syndrome. This probably results from the fluid in the anterior chamber moving posteriorly when the patient blinks. The scleral sutured PCIOL reverse pupillary block seems to be more common in individuals who have less rigid corneas, such as young people, but it can occur in anyone. If the pupil is small, the reverse pupillary block tends to cause pigment dispersion and inflammation. If the pupil is of moderate size or pharmacologically dilated, the reverse pupillary block can be significant enough to push one side of the pupil margin behind the corresponding IOL edge. Although this configuration enables fluid to flow both anteriorly and posteriorly, it usually causes notable pigment dispersion, iritis, and sometimes even iris sphincter damage from the mechanical action between the iris and the IOL. One may have the impression that this abnormal iris configuration is from a poorly positioned IOL, but unless the IOL is highly tilted, the cause is most likely to be from reverse pupillary block.

Because it is not possible to predict exactly which patients with scleral sutured PCIOLs will develop reverse pupillary block, there is merit to creating peripheral iridectomies (PIs) in all patients undergoing the procedure. The openings need to facilitate rapid flow of aqueous through the iris if all degrees of reverse pupillary block are to be avoided. This is in contradistinction to the small, low-flow peripheral iris openings created with a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser to treat standard pupillary block or prevent angle closure. Experience has shown that two iridectomies ∼ 0.7 mm in diameter enable adequate flow. Alternatively, a single iridectomy ∼ 1.2 mm in diameter should suffice. The main advantages of the two smaller iridectomies is that there is probably less potential for unwanted optical sequelae than with a larger one, and the smaller ones are also less noticeable from a cosmetic standpoint, particularly in light-colored irides. Superior placement of the iridectomies peripheral to the optic of the IOL minimizes cosmetic side effects and does not seem to produce the dysphotopsias described in recent literature with small peripheral laser iridotomies performed in phakic patients. Because a vitrectomy is performed during most sutured PCIOL cases, a very good tool for creating iridectomies is usually already available—the vitrectomy probe (see Peripheral Iridectomy Creation with a Vitrectomy Probe, below). If a patient with a scleral sutured PCIOL who does not have a peripheral iridectomy (or who has too small of an iridectomy) develops the partial optic capture situation, then the use of dilating drops to attempt to get the pupil larger than the optic and release the partial capture configuration can help stop pigment dispersion, iris injury, and inflammation. If dilation works, then the dilation should be maintained until appropriately sized peripheral iridectomies can be created.

Transscleral Sutured Posterior Chamber Intraocular Lens Technique: Example

The following is a description of the technique with which I have two decades of experience, and for which I can provide the most insights. It is an ab-interno technique that uses small-diameter spatula needles, which have the advantage of the smaller tract that they create through vascularized tissues. Good to excellent eye pressurization is maintained throughout the procedure. IOL centration is reliably achieved using visual cues, with the second set of suture needles being passed from a paracentesis anterior to the suture location for the first haptic. (To the best of my knowledge, this maneuver is unique to the way I have been doing scleral sutured IOLs, and is something I have presented at a film festival with coauthors.4) Ab-interno techniques, like this one, may be a bit challenging for surgeons not accustomed to passing long, curved trans-chamber needles across the eye, but with practice, proficiency can be achieved. In the procedure description there are some general comments about instrumentation, alternate maneuvers, and tips on how to avoid problems that should broaden the usefulness of the description. At the end of the description there is an explanation of the variation I employ to allow use of expanded polytetrafluoroethylene (e-PTFE) suture (Gore-Tex, W.L. Gore & Associates, Flagstaff, AZ). After the procedure description, there is a discussion of various aspects of scleral sutured PCIOLs. After the iris-sutured IOL part of this chapter, there is a more detailed discussion of various aspects of scleralsutured PCIOLs.

Procedure Description

Dilating drops are used prior to the procedure, but wide dilation is not as necessary as it is in cataract surgery. In fact, a pupil that is too widely dilated may be a hindrance because the iris tends to bunch up posteriorly and can get in the way of suture passes. If iris hooks are used during the removal of a dislocated IOL, then after the old IOL is removed, the surgeon may want to loosen, or remove the hooks in the areas where the sutures are to be located prior to placing a scleral sutured IOL. A retrobulbar or peribulbar block maximizes patient comfort and decreases ocular motility, but other anesthesia options are also reasonable, such as topical plus subconjunctival anesthetic injection. After placement of a lid speculum, I place superior and inferior rectus 4-0 silk bridle sutures to be able to stabilize, reposition, and even elevate the globe. The ability to elevate the globe is particularly helpful if the eye is relatively enophthalmic. Using a taper point needle on the 4-0 silk increases safety by decreasing the risk of globe penetration and bleeding. A Paufique forceps facilitates placement of bridle sutures because the size and angulation of the teeth on the tip of the forceps enable the surgeon to readily grasp the muscle tendon insertion area, rather than just grasping conjunctiva and Tenon’s capsule. If a superior incision is planned, then I create a radial relaxing incision in the conjunctiva at the 10:30 clock position with a peritomy over to the 1:30 position. Next is a second radial relaxing incision in the conjunctiva at the 4 o’clock position and a peritomy carried over to the 6 o’clock position. Cautery in the exposed scleral beds is useful to help visualization of incision and suture placement. I create a half-thickness scleral groove on the superior sclera that is 7 mm wide in a “frown” configuration, with the anteriormost portion of the incision still being posterior enough to be in scleral tissue. I use a sharp, bi-bevel scleral tunneling blade to dissect anteriorly from the base of the groove in a lamellar fashion into clear cornea. To keep the dissection in a single, contiguous plane, I use wide, sweeping strokes across the entire width of the tunnel with gentle pressure at the tip of the tunneling blade to avoid deforming the tissues as the dissection proceeds. (Note: If a temporal wound is utilized, then the clock hours of the preceding and following descriptions are adjusted accordingly.)

Paracenteses at about the 10 o’clock and 2 o’clock positions are convenient locations through which to place the self-retaining infusion cannula and the vitrectomy probe. I prefer a reusable, titanium, high-flow infusion cannula (model 8–616, 20-gauge; model 8–616–1, 23-gauge; Duckworth & Kent, Baldock, UK) because it is designed with a smaller tip that facilitates entry into the paracentesis. Disposable, stainless steel cannulas, like the Lewicky infusion cannula (various manufacturers), work well, too. Infusion should be kept in the “continuous” mode throughout the procedure, with infusion only being turned off during certain times, such as prior to opening the main incision. With a gravity-feed system, a bottle height of 60 to 70 cm is usually about right during vitrectomy, but during most of the rest of the procedure, when the vitrectomy probe is not actively aspirating fluid, a bottle height about half as high is more advantageous. I usually remove the vitreous from about the anterior half of the vitreous cavity, particularly in the areas where the IOL sutures will be passed.

Incision Construction and Management

After completing the vitrectomy, the main incision is completed by opening the corneal portion of the incision in a corneal valve configuration with a sharp-tipped keratome ∼ 3 mm wide. I usually use an enlargement blade next (∼ 5.5 mm wide), still paying attention to the Descemet’s incision line to maintain the corneal valve. I complete the enlargement to the 7-mm width using the sides of the enlargement blade. Alternatively, the sharp-tipped keratome may be used for the full wound enlargement, but in doing so, even more care and attention is needed to achieve a self-sealing incision. As the incision is enlarged, I try to maintain a corneal valve all the way to the sides of the incision for optimizing the ability of the incision to seal. In so doing, the Descemet’s incision usually has a bit of a “smile” configuration, which has the mirror appearance of the “frown” configuration of the scleral groove. If the Descemet’s enlargement incision tracks back to the limbus (through Schwalbe’s line), then the corneal valve effect of the incision is usually lost and the incision will generally not self-seal. In this situation a significantly increased number of sutures may be required to achieve a watertight closure (Fig. 27.1) (see Incision Enlargement Technique, below).

I prefer using a one-piece PMMA IOL with a 7-mm optic with eyelets on the haptics (Alcon model CZ70BD) because of the rigidity it offers in spanning the distance across the front of the eye, and the presence of the eyelets. I calculate the IOL power as if it were a sulcus-placed lens, which usually achieves the desired refractive outcome. My standard suture has been a 3-inch-long double-armed 9-0 polypropylene suture with curved, long, trans-chamber, spatula needles (for example, Ethicon CTC-6L needles as a special order on 9-0 Prolene, D-8229; Ethicon, Somerville, NJ), which I pass through the eyelet on the lead haptic of the IOL. (This length of suture is long enough for the procedure; longer lengths have the tendency to get tangled more easily.) The suture is arranged so that one arm of the suture emerges through the top of the eyelet and the other arm comes over the top of the haptic between the optic and the eyelet (Fig. 27.2). Having the non-eyelet suture arm come over the haptic between the eyelet and the optic decreases the risk of the suture arm inadvertently flipping over the tip of the haptic, in which case that suture arm would emerge below the haptic and have the potential to induce tilt (see Suture Configuration on Haptics and Intraocular Lens Tilt, below).

Infusion Management

During the IOL placement and IOL suturing, a relatively low infusion pressure, around 30 cm of water, helps minimize the intraocular pressure fluctuations, and decreases the risk of the iris prolapsing out through the main incision. If the iris does prolapse, then turning off the infusion for a few moments will soften the eye enough to allow gentle repositing of the iris. An additional way to help prevent iris prolapse when the main wound needs to be opened is to turn off the infusion for several seconds before opening the main wound, so that there is even less of a pressure gradient and hence minimal fluid flow out through the main incision when it is opened. Setting up the machine so that the surgeon can turn the infusion on and off with the foot pedal, as well as raise and lower the infusion bottle with the foot pedal, can facilitate the procedure. Pump-based fluidics on the machine tend to create greater flow when the eye is opened for an equivalent static pressure setting, and hence are not as user friendly for this type of surgery. If a machine with pump-based fluidics is utilized, then additional attention should be paid to turning off the infusion before opening the main incision.

First Suture Placement: Right-Hand Needle

The suture arms are physically separated on the field to keep track of which should be on the right and which should be on the left, so that they are later placed through the sclera in the correct orientation. The right-side needle is then passed through the main wound, which is slightly gaped open with an instrument, such as an angled tying forceps, to create space so that the needle tip does not catch corneal or scleral tissue inside the wound. After visualizing the needle tip in the anterior chamber, the surgeon can move the needle side to side to be sure that it has not caught any sclera or corneal tissue in the main incision. The needle tip is then passed through the pupil, under the 5 o’clock iris position and into the ciliary sulcus area. An angled tying forceps placed on the sclera near the anticipated needle exit point can be used to palpate the needle tip through the sclera and verify that the needle tip is in the desired position. The slightly open tying forceps can be used for counterpressure on the sclera and to grasp the needle tip when it emerges from the sclera ∼ 1.5 to 3.0 mm posterior to the limbus (Fig. 27.2). If the needle emerges in a place other than the desired location, it can be pulled back into the eye and an additional attempt can be made to place the needle in the preferred location. Once the needle shaft is about halfway through the sclera, the surgeon can pivot the needle side to side in its track through the sclera. If the iris shows corresponding motion, then this suggests that the needle pass has caught the peripheral iris, and the needle may be retracted back by gently pulling on the suture until it can be regrasped with the needle holder to make another pass without catching the iris. Reaching a location far enough behind the iris can sometimes be more challenging in large eyes due to the dimensions involved.

First Suture Placement: Left-Hand Needle

The left-hand needle is then passed through the main incision and pupil in the same manner that the right-hand needle was just passed. The needles should emerge from the sclera the same distance posterior to the limbus and ∼ 1.5 mm apart from each other (Fig. 27.3). The needle passes may be closer to each other, ∼ 1.0 mm, but when they get too close it becomes more difficult to bury the knot, and some of the four-point fixation effect becomes diminished (see Suture Configuration on Haptics and Intraocular Lens Tilt, below). The suture needle is 6 mil in diameter (0.006 inches or ∼ 0.15 mm in diameter). It is less than one fifth the width of a 24-gauge microvitreoretinal (MVR) blade (0.80 mm wide), so the potential for causing bleeding with transscleral passes with this needle should, theoretically, be lower than with ab-externo sclerotomies made with a 24-gauge MVR blade, and in my experience reality follows the theoretical difference. Surgeons who prefer an ab-externo approach, but still want to use 9-0 polypropylene attached to this type of suture needle often use a 27-gauge hollow-bore needle passed through the sclera from the outside of the eye. They dock the suture needle into the 27-gauge needle before it is brought out through the sclera.

Needle Position

Other locations around the eye for placement of the sutures may be selected by the surgeon if it facilitates passing the needles. That said, it is probably best to avoid the 12 o’clock and 6 o’clock positions to minimize the chance of hitting larger ciliary vessels, and also to avoid the 3 o’clock and 9 o’clock positions for the same reason, and to avoid the trunk area of the long ciliary nerves. The appropriate distance posterior to the limbus for the needle to go through the sclera in each eye is actually determined by internal anatomy, which varies from patient to patient. The needle should pass through the sclera posterior to the iris so that no peripheral anterior synechiae are created when the lens haptic is later pulled into position. The limbus is closer to the iris nasally and temporally than superiorly and inferiorly, so even in a given eye, the distance from the limbus to the appropriate place for the sutures varies depending on where around the circumference of the eye the sutures are placed. Aids for helping determine the location of the suture needle tip behind the iris before placing it through the sclera include “tickling” the back of the iris with the needle tip, mentally visualizing where the needle tip is located, and palpating the sclera.

Needle Basics

A titanium angled tying forceps is better for grasping the emerging needle because titanium instruments have better grip on stainless steel needles (due to more friction) than stainless steel instruments do. Also, using a tying forceps that is stouter than the typical fine-tying forceps helps hold the needle better and minimizes unexpected needle movement from forceps scissoring. The process of grasping and pulling the needle through the sclera is best broken down into three distinct steps: (1) Grasp the needle tip with the tying forceps, preferably with the flats of the tying forceps on the flat aspects (top and bottom) of the spatula needle. (2) Release the needle holder’s grasp of the back end of the needle. (3) Pull the needle out through the sclera with the tying forceps. Although these steps seem quite intuitive while reading them, it is rather easy for a surgeon, who is focusing on the needle tip, to still hold onto the back end of the needle with the needle holder while trying to pull the tip of the needle out through the sclera with the tying forceps. The needle holder always wins, and the needle tip often pops back inside the eye, causing a setback in the flow of the surgery and often a dulled needle tip that is harder to re-pass through the sclera.

Insertion of an Intraocular Lens

After both needles have been passed, the two arms of the suture are grasped with a straight tying forceps outside the eye to pull up the suture slack as the IOL is placed in through the main incision with the angled tying forceps. The lead haptic is directed into the ciliary sulcus area where the sutures pass through the eye wall (Fig. 27.4a). The trailing haptic can be left in the main incision with part of the haptic just outside the eye so it is easier to later place the second suture on the trailing haptic. Having the trailing haptic in this position causes a little bit of fluid leakage out through the main incision, but the eye still remains well formed, and if the surgeon needs to raise the pressure in the eye, such as in the case of significant intraocular bleeding from the needle pass, then the haptic may be temporarily placed into the anterior chamber so that the incision can seal more completely.

Management of Needle Entrapment in the Incision

When the surgeon starts placing the IOL into the eye, it will become apparent if one of the needles caught some tissue inside the main incision because the lead haptic will stop progressing at the main incision, and the wound will deform. If this occurs, then small amounts of corneal or scleral tissue may be carefully cut with fine scissors to free the suture. If the amount of tissue is significantly greater, then the IOL may be pulled back out of the eye, and the suture may be cut in an appropriate location to enable freeing of the suture material that is caught in wound tissue. After the suture is freed, then the cut suture ends can be tied back together. This area of suture that has been retied will work fine for placing the IOL and suture in the desired location, but it should not be utilized as part of the suture that creates the final securing of the IOL to the sclera.

Once the IOL is in the eye with the lead haptic in the desired location behind the iris, the two suture arms can be carefully tied together with a 2–1-1–1 knot, being sure that each throw is laid down square and the suture arms are evenly tensioned to optimize knot configuration and strength. After the knot is tied, the arms are trimmed and the suture is rotated to bury the knot inside the eye (Fig. 27.4b,c) (see Suture Knot Management, below).

Second Suture Placement

To minimize the potential of sutures becoming tangled, it is not until this point in the procedure that the surgeon brings a second double-armed 9-0 polypropylene suture with curved, long, trans-chamber, spatula needles into the surgical field and passes one of the needles through the eyelet on the trailing haptic (Fig. 27.5a). This suture is also arranged so that that one arm of the suture emerges through the top of the eyelet and the other arm comes over the top of the haptic between the optic and the eyelet. The suture arms and needles are placed on the drapes off to their respective sides. I place an angled mini-IOL manipulator (model 6–418, Duckworth & Kent) in the eyelet on the trailing haptic and use it to push the haptic in through the main wound, down through the pupil, while keeping the suture in the correct position on the haptic (Fig. 27.5b). The haptic is then released by turning the handle of the instrument obliquely away from the surgeon so that the knob rotates out of the eyelet. If the specified mini-IOL manipulator is not used, but a different instrument is going to be placed into the eyelet of the trailing haptic, then care should be taken to select an instrument that will fit into the eyelet, yet not get stuck in the eyelet (Fig. 27.5b inset). If such an instrument is not available, then one may choose to use forceps to place the haptic into the eye, or a different type of IOL manipulator on the outside of the haptic itself. The instrument that is used to put the trailing haptic into the eye can also be used to push the optic a little bit posteriorly to move the trailing haptic posterior to the ciliary sulcus so it is out of the way while passing the next suture needle.

I then create an additional paracentesis that is directly anterior to the location of the suture for the lead haptic—at about the 5 o’clock position. One of the needles for the trailing haptic suture is grasped a couple of millimeters from its tip with a needle holder, keeping track if it is attached to the right- or left-side suture. The needle is passed butt-end first in through the main wound, across the anterior chamber and partway out through the 5 o’clock paracentesis opening (Fig. 27.6a). With the butt end of the needle outside the eye at the 5 o’clock position, the surgeon is able to regrasp the needle at its back end with the needle holder. The needle tip can then be redirected through the pupil, under the 11 o’clock iris position and into the ciliary sulcus area (Fig. 27.6b). Because the needle is in a paracentesis that is directly anterior to the suture for the first haptic, the proper location for the placement of the suture for the trailing haptic can be determined by visualizing the needle as splitting the anterior segment into two equal parts before passing the needle through the sclera. For this centration method to be effective, the curved needle needs to be oriented with the plane of the needle’s curve, oriented perpendicular to the plane of the iris—in other words, so that the needle appears essentially straight from the surgeons view (Fig. 27.7). If the surgeon desires additional help in getting the correct placement of the sutures in this or other transscleral suturing techniques, then an aid such as an inked, 180-degree marker may be used, like the type of device used to mark the axis for a toric IOL. Some surgeons place the suture through sclerotomies positioned further apart from each other, and attach the IOL to the suture using a hitch so that centration may be adjusted after the IOL sutures have been tied and the knots buried.5 The second needle is passed in the same way, either to the left or to the right of the first needle, depending on whether it is attached to the left- or right-side suture.

The decision of whether to pass the right-side or the leftside suture first for the trailing haptic may be influenced by the position of the trailing eyelet and the sutures inside the eye. If the eyelet is to the right of the desired location for the needle pass, then it will usually pull the sutures to the right of the desired suture location. In this scenario, passing the left-side suture first minimizes the risk that it will become crossed and twisted with the right-side suture. Once the left-side suture is placed, and the slack is taken up on the suture, then the left suture is positioned down and out of the way so the right-side suture is unlikely to cross it and create a twist. Likewise, if the eyelet is pulling the sutures to the left of the desired location for the suture placement, then passing the right-side suture first is advantageous.

Evaluation of Intraocular Lens Position and the Use of Purkinje Images

After the slack is taken up on the suture for the trailing haptic, the bridle sutures can be loosened, and the eye may be turned so it is facing directly toward the microscope. If one sees the broad reflection, or Purkinje image, off the anterior surface of the Alcon model CZ70BD IOL, when the eye is in this position and the trailing sutures are tensioned, then that is confirmation that the lens does not have significant tilt. If the reflection is not seen initially, then the eye can be rotated until the reflection is seen. Based on the direction that the eye is facing when the IOL reflection is visible, one can determine if there is a clinically significant amount of IOL tilt, or if it is insignificant. If a small amount of IOL tilt is present, it is sometimes possible to reduce the amount of tilt by either increasing, or decreasing the tension on the sutures for the trailing haptic. If the tilt is improved in this way, then the suture can be tied with either a bit more or a bit less tension to help decrease the tilt. If the amount of tilt is still unacceptable, then sometimes the IOL tilt can be reduced by using an instrument through one of the paracenteses to change the lens position, prior to tying the suture for the trailing haptic, which further secures the IOL in position. Fortunately, with the IOL suturing technique as described, it is rather unusual to see significant IOL tilt, so these rectifying measures are rarely needed. Once the IOL position is determined to be satisfactory, then the suture for the trailing haptic should be tied, trimmed, and the knot buried in the same fashion as was performed for the lead haptic.

An even more specific test for evaluating the IOL for lack of tilt and proper centration is if one is able to simultaneously see (1) the bright microscope light reflection off the front of the cornea positioned in the center of the cornea (first Purkinje image, P1), (2) the broad reflection off the front of the IOL (third Purkinje image, P3), and (3) the reflection off the back of the IOL (fourth Purkinje image, P4) positioned rather close to P1. P4 appears as a dimmer, inverted, and side-to-side flipped image of P1. If one aligns P1 in the center of the cornea, and P3 is visible (and centered if it is not a broad reflection), but P4 appears notably shifted off to the side, then that means the IOL does not have tilt, but that it is decentered. Retraction of the iris at the pupil margin can help one visualize the optic to determine the amount of decentration to decide if there will be IOL edge exposure issues, which might necessitate re-suturing one of the haptics. With other IOL designs and materials, some characteristics of P3 and P4 may appear different from those described (Fig. 27.8). (Note: P2, off the back of the cornea, is never visible because it is directly behind P1 and much dimmer than P1.)

Incision Closure

The main incision is usually rather watertight due to its corneal valve configuration, and fairly stable with the frown configuration architecture, so three interrupted 10-0 nylon sutures are generally adequate to further stabilize the incision; more sutures should be placed as needed. When placing the 10-0 nylon sutures, care should be taken to avoid cutting the superior haptic’s 9-0 polypropylene suture with the needle of the 10-0 nylon suture. If a 10-0 nylon suture needs to be placed in the area of the suture supporting the haptic, then it can be placed in a “bridge” configuration by going through the top of the scleral tunnel, then skipping over the polypropylene suture before taking a bite of sclera further posteriorly. If the 9-0 polypropylene supporting the trailing haptic is cut with the needle from the 10-0 nylon, then one can remove the 10-0 nylon sutures from the main incision before using an instrument like a cyclodialysis spatula, or a straight IOL manipulator to go through the main incision, through the pupil, and under the left side of the IOL to catch the trailing haptic, elevate it, and bring it back out through the main incision. The trailing haptic can then be re-sutured just as had already been done.

If the pupil has not spontaneously become fairly small, then injecting acetylcholine chloride (e.g., Miochol-E, Bausch & Lomb, Rochester, NY) into the anterior chamber to constrict the pupil is helpful prior to creating the superior peripheral iridectomies. If the pupil becomes relatively small prior to placing the sutured IOL, then creating the peripheral iridectomies, at that time, can decrease the iris fluctuations as fluid moves about inside the eye during insertion and suturing of the IOL (see Peripheral Iridectomy Creation with a Vitrectomy Probe, below). After creation of the peripheral iridectomies, the infusion cannula is removed. Stromal hydration may be performed, as needed, to ensure sealing of the paracentesis incisions. At this point the bridle sutures can be removed, and then the conjunctival flaps can be repositioned and held in place with 10-0 polyglactin (Vicryl, Ethicon) sutures, or another suture of the surgeon’s choice. Because the conjunctival flaps cover the IOL sutures that go through the sclera, it is important that these flaps be secured so that they adequately cover, and heal in place over the IOL sutures. It is probably better to avoid cautery closure of the conjunctival flaps in these cases because the closure is not as secure as with a suture, and the cautery creates burned, dead tissue which could be a nidus for bacterial growth relatively near the transscleral sutures. I place subconjunctival injections of dexamethasone and cephazolin, with topical drops of fluoroquinolone and 5% povidone-iodine solution prior to placing some viscoelastic on the cornea and patching the eye.

Ab-Externo Variation with e-PTFE Suture Material

For certain patients, it seems appropriate to use suture made of e-PTFE in the smallest size manufactured, CV-8 (Gore-Tex)57

(see Suture Material and Suture Needles, below). Because this suture is not available on needles that can cross the anterior chamber of the eye, it is necessary to use an ab-externo technique. I perform this procedure the same way as described for the 9-0 polypropylene, with the following exceptions.

An angled 24-gauge MVR blade (0.8 mm wide) is used to create the scleral openings through which the sutures can be passed. I create the incisions for the lead haptic first, passing the blade through the sclera parallel to the iris. I choose the location to make the scleral incisions in an analogous fashion to how I place the 9-0 polypropylene sutures, by visualizing where the iris is, and trying to make the incisions an appropriate distance behind the iris. I like to pass the MVR blade centrally enough so that I can see its tip in the pupil to verify that I have made the incisions in the correct location. A sterile pen is useful to mark the round shaft of the blade just behind the cutting edges prior to each pass through sclera so that the scleral openings are easier to locate when one wants to pass coaxial forceps through the incisions. I use a cyclodialysis spatula held over the cornea so that the heel of the spatula is lined up between the sclerotomy incisions for the lead haptic and then position the tip of the spatula so that the cornea is visually bisected to see where to make the incisions for the trailing haptic sutures. I mark the 180-degree spot on the limbus with the sterile pen and then make the sclerotomies in the same fashion, just to the left and right of that mark, the same distance posterior to the limbus as the first pair of sclerotomies.

After threading a 7-cm piece of e-PTFE through the lead haptic in the same fashion as for 9-0 polypropylene technique, I pass one suture arm in through the main incision and down through the pupil with an angled tying forceps. I use a 25-gauge coaxial forceps to retrieve the suture end, usually employing a second instrument, such as an angled IOL manipulator, through a paracentesis to help move the suture into the open jaws of the forceps. A curved 25-gauge coaxial forceps facilitates suture retrieval. When reusable forceps (e.g., Snyder Grasping Forceps, DFH-0032, MicroSurgical Technology, Redmond, WA) are not available, then one can manually bend a curve into a pair of straight disposable retinal forceps using one’s fingers. Adjusting the bridle sutures to rotate the eye can be very helpful during suture retrieval to work around periocular anatomy constraints. The second arm of the e-PTFE is brought through its corresponding scleral incision in the same fashion, and then the IOL is placed into the eye as is done with the 9-0 polypropylene technique. I tie the e-PTFE with a five-throw (2–1-1–1-1) knot to decrease the risk that the knot will loosen to the point of integrity loss in this slippery suture material. A 4-cm piece of e-PTFE is placed through the eyelet in the trailing haptic in the same fashion before placing the trailing haptic into the eye with the left and right suture arms left hanging out of the main incision and placed to their corresponding sides. With a second instrument pushing the optic a bit posteriorly, the 25-gauge forceps is placed through each of the scleral openings to grasp the sutures between the haptic and the iris, and then the suture ends are fed into the main incision, to minimize iris perturbation, as the sutures are extracted through the 24-gauge scleral incisions. The reason to push the IOL posteriorly is to minimize the risk that the 25-gauge forceps will enter the eye behind the haptic instead of in front of it. The knots for the trailing haptic e-PTFE are tied in the same fashion. I rotate the knots into the eye using a combination of grasping the suture with tying forceps to rotate the suture, and pushing the knot in through the sclera. I find the knob of the angled mini-IOL manipulator very helpful for pushing the knots in through the scleral incisions; the closed tip of the 25-gauge forceps, or one tip of an open tying forceps may also work.

Iris Sutured Posterior Chamber Intraocular Lenses

The practice of using the iris to support IOLs began in the late 1960s and lasted well into the 1970s during the intracapsular cataract extraction era with lenses such as the Copeland irisplane IOL.8 The shift from the purely iris-supported IOL to IOLs supported by the lens capsule and the iris was associated with improved visual results, as well as decreased rates of cystoid macular edema, uveitis, and other complications.9 This shift also corresponded to the change from intracapsular to extracapsular cataract extraction techniques, so it is difficult to know how much of the difference was due to the change in IOL support versus the change in extraction technique. With that in mind, it is interesting that currently many surgeons’ preferred use of iris sutured PCIOLs is in situations where the haptics are in the sulcus region or the lens capsule offers additional support to the IOL. Today, suturing a PCIOL to the iris generally involves creation of a pupillary capture of the optic of the PCIOL into the anterior chamber while the haptics remain in the posterior chamber. Sutures are passed down through the iris, under the haptic, and then back up through the iris. The sutures are tied either before or after repositing the optic back through the pupil into the posterior chamber.1012

Indications and Other Considerations

Suturing a PCIOL to the posterior surface of the iris may be a desirable procedure in several situations:

  1. Stabilizing or centering an IOL that was placed in the sulcus during a prior, or current cataract surgery. In this situation the IOL is already reasonably supported by the remaining lens capsule, but due to zonular defects, or the IOL overall diameter being smaller than the eye’s sulcus diameter, the IOL is mobile, or decentered.
  2. Primary placement of an IOL when there have been complications during cataract surgery, and there is inadequate capsule support to be able to place a sulcus-only supported IOL.
  3. Secondary placement of an IOL, alone or as part of an IOL exchange, in an eye with inadequate capsule for a sulcus-only supported IOL.

Of these three scenarios, the first is probably the strongest indication for this procedure because the iris is only required to add a relatively small amount of support to the IOL, so there is less traction on the iris from the sutures, and with less iris traction there is decreased stimulus for inducing uveitis. Suturing PCIOLs to the back of the iris involves the use of long, curved trans-chamber type needles, which may be a bit challenging, at first, for surgeons not accustomed to using them. The procedure also involves intraocular knot tying, which may or may not be a skill with which the surgeon is already comfortable.

Intraocular Lens Selection

The IOLs for this procedure optimally have (1) rounded optic edges; (2) rounded, small-diameter haptics; and (3) an overall diameter that is large enough to offer some support to the IOL from the haptics’ being able to rest in the ciliary sulcus.

If there is already an IOL in the sulcus in the eye, then that IOL should be considered as the first option, unless it has square-edged haptics or the power is considerably off from the desired power. Square-edged haptics have a notable rate of inducing uveitis, pigment dispersion, glaucoma, and hyphema when they are in the sulcus, particularly if the haptics are in contact with the iris, so these IOLs generally should be avoided when choosing a PCIOL to suture to the iris.13,14 Once an IOL is sutured to the iris, then it effectively becomes a sulcus IOL and has close contact with the back of the iris. If the IOL in the eye is a one-piece or three-piece PMMA IOL with rounded edges and haptics, then keeping that IOL in the eye has the advantage of not needing to create an incision large enough for removing the nonfoldable IOL. It can be a little more challenging to get the optic in front of the pupil with one-piece PMMA IOLs due to the greater rigidity of the haptics, but once optic capture has been achieved and maintained, these relatively rigid haptics are easier to see and suture because they tent the iris forward better when the haptic or optic is pulled anteriorly.

If there is not an IOL in the eye, then foldable three-piece silicone optic IOLs can be a good choice because they virtually all have rounded edges on the optic and small-diameter round haptics. If there is no capsule support, and one wishes to achieve contact between the haptic and the ciliary sulcus for added support, then an IOL with a larger overall diameter is needed. Capsular bag IOLs usually have an overall diameter in the 12.5- to 13.0-mm range. In the United States, a foldable silicone IOL that has been available until 2016 with the larger, 13.5-mm overall diameter is the model AQ2010V of Staar Surgical (Monrovia, CA). In 2009, the American Society of Cataract and Refractive Surgery (ASCRS) Cataract Clinical Committee found this lens to be the most commonly selected IOL for sulcus placement,14 suggesting that it performs well in that anatomic location. A foldable three-piece IOL with a square-edged optic (generally acrylic), and round haptics can be considered for suturing to the iris, but in a sulcus-like position the square edges of the optic have the potential to cause iris chafing with pigment dispersion, uveitis, and other problems.15

Procedure Description

Preoperatively, it is usually best not to use drops that dilate or constrict the pupil because too large or too small of a pupil makes it difficult to position the IOL for the creation of optic capture. Although other anesthesia options are reasonable, a retrobulbar/peribulbar block is generally a good choice for this procedure because akinesia facilitates performing the procedure, and the block provides patient comfort during the iris manipulation involved in this procedure. Superior and inferior rectus bridle sutures may be useful for elevating globes when the exposure is poor, or when the surgeon desires a more stable eye (see Procedure Description under section Transscleral Sutured Posterior Chamber Intraocular Lens Technique: Example, above, for additional bridle suture description, and see Chapter 1 for information about a peribulbar anesthetic).

Surgeon Position

The surgeon may elect to sit superiorly or temporally. Factors that influence the surgeon’s seating position include (1) the best location for the main incision if an IOL needs to be put into the eye or exchanged; (2) the level of exposure of the globe, because passing long, curved, trans-chamber needles can sometimes be difficult if the brow or nose is in the way; and (3) the most comfortable position for particular maneuvers. The surgeon may change position during different parts of the procedure as needed to optimize performance of the various maneuvers.

Eye Pressurization

The optimal method for maintaining the pressure in the eye and the formation of the anterior chamber depends on whether or not there is an intact lens capsule diaphragm. If the diaphragm is intact, then an ophthalmic viscoelastic device (OVD), preferably dispersive, may be used. If the diaphragm is not intact, an anterior chamber infusion cannula can then be used with an infusion bottle to keep the eye formed and pressurized. Mydriatic agents, such as epinephrine or phenylephrine, should not be placed into the infusion bottle during these cases because it can make it difficult to achieve a solid optic capture. Any vitreous in the anterior chamber or area behind the iris should be removed with a vitrectomy probe placed through an incision matched to the size of the vitrectomy probe, usually through a limbal paracentesis. The bottle height during the IOL fixation should be high enough to keep the eye well formed, yet not so high as to create rapid fluid flow out through the paracenteses as they are opened by instruments passing through them. A bottle height of 30 to 35 cm usually achieves both of these goals. If vitrectomy needs to be performed, then the bottle height usually needs to go to almost twice this height, and a high-flow anterior chamber infusion cannula should be used (e.g., model 8–616, 20-gauge; model 8–616–1, 23-gauge; Duckworth & Kent). If one has a choice between gravity flow versus an active pump on the machine for the infusion, it is probably better to select the gravity flow option for this type of procedure because the active pump systems tend to create more flow through open incisions than is optimal.

Intraocular Lens Positioning

If the desired IOL is already in the posterior chamber, then it should be rotated so that the haptics are in the position in which the surgeon wishes to have them for placing the securing sutures through the iris. The optic can then be lifted up through the pupil with instruments such as a cyclodialysis spatula, various IOL manipulators, or intraocular forceps that have textured or serrated jaws. The general approach is to bring an instrument, such as a cyclodialysis spatula, in toward the optic 90 degrees away from the optic–haptic junctions, then depress the pupil edge, and slide the instrument under the optic to lift it. If the pupil is smaller than the optic, then the first instrument may need to be one with a hook or knob on it to retract the pupil edge prior to sliding the instrument under the optic (Fig. 27.9). In the situation of a small pupil, a second instrument may be needed on the opposite side to press the iris down under the optic. Moving the second instrument along the opposite side of the optic to progressively slide the iris under the optic may be helpful in a maneuver called “tire ironing,” named after the motion of a tire iron when removing a tire from its rim. If the surgeon has appropriate coaxial intraocular forceps available to grasp the optic to elevate it, then that can sometimes facilitate the process. If the pupil is small enough, optic capture may be achieved with just these maneuvers. If the pupil is about the same size as or larger than the optic, a small amount of miotic agent can be injected into the anterior chamber to constrict the pupil to achieve optic capture after the optic has been moved anterior to the iris. Acetylcholine (e.g., Miochol-E, Bausch & Lomb) is generally the preferred agent because it causes miosis more quickly than carbachol.

May 13, 2018 | Posted by in OPHTHALMOLOGY | Comments Off on Scleral and Iris Sutured Posterior Chamber Intraocular Lenses and Intraocular Knot-Tying Techniques
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