Cataract Surgery, 3rd Edition

PART V – Special Techniques for Cataract Extraction

Chapter 31 – Iris Repair

Michael E. Snyder, MD,
Roger F. Steinert, MD,
Christopher. Khng, MD,
Scott E. Burk, MD, PhD


Contents

  

   

Iris Reconstruction

  

   

Case Studies in Iris Reconstruction

  

   

Iris Prostheses

CHAPTER HIGHLIGHTS

  

   

Principles of iris repair

  

   

Techniques of iris suturing

  

   

Iris prostheses

  

   

Case studies

Iris abnormalities that present in conjunction with cataract or intraocular lens (IOL) surgery are usually the result of accidental or surgical trauma. Less commonly, the iris abnormalities may be congenital, such as an iris coloboma or corectopia, or the abnormality may be the result of a later-onset degenerative process.

Penetrating injuries of the cornea or anterior sclera may result in iris injury from direct laceration or as a consequence of iris prolapse through the wound. Blunt, nonpenetrating trauma to the anterior segment may also injure the iris.[1–3] The most common patterns of iris injury after severe blunt trauma are localized sphincter tears, generalized sphincter paralysis, and dialysis of the iris root.[4]

Preservation of iris tissue and restoration of normal iris architecture are important for two principal reasons. Most importantly, the optical performance of the eye is highly dependent on the pupillary aperture. Higher order optical aberrations and lens edge effects, in particular, are more prominent at larger pupil apertures.

A large and nonreactive pupil results in photophobia and glare. In addition, aberrations from the peripheral cornea, as well as the peripheral IOL and/or exposed capsule, can be highly disturbing to the functional vision of a patient. Pupillary distortions are better tolerated by a patient with a clear crystalline lens than a pseudophakic patient because the IOL has a substantially smaller optical diameter than the crystalline lens.

The first step in the management of traumatic iris abnormalities is, therefore, to minimize further damage to the iris and to preserve as much iris tissue as possible. Prolapsed iris tissue does not necessarily need to be excised; the surgeon performing the primary repair must judge the likelihood of microbial contamination of the iris before sacrificing a prolapsed iris.

Iris reconstruction

Surgical principles of iris suturing

Although iris deformities have an infinite number of possible configurations, the basic principles of surgical repair can be summarized in a few basic techniques.

Principle 1: Mobilization

The first principle is to free up and mobilize as much iris tissue as possible. Synechia to the cataract or capsule should be bluntly dissected. Most iridocapsular adhesions are strongly attached only at the sphincter edge. Often there is some proliferation of iris pigment epithelium from the posterior iris surface to the capsule involving the more peripheral iris, but these adhesions are weak and can be easily separated with an instrument such as a cyclodialysis spatula or a cannula with viscoelastic agent. If iridocapsular adhesions cannot be bluntly dissected, then careful excision with a scissors or blade should be performed, preserving as much iris tissue as possible by taking care not to excise any iris tissue that is salvageable.

After freeing up all iridocapsular adhesions, the surgeon should then release any peripheral adhesions. Peripheral anterior synechia usually can be released with traction using forceps or a pointed hook such as a Sinskey hook or Osher Y hook or by sweeping maneuvers with a spatula. In addition, inflammation sometimes causes the iris stroma to form adhesions internally, causing contraction of the iris in a manner similar to accordion pleats. Again, gentle traction can release many of these adhesions and produce a surprising amount of iris tissue necessary for the subsequent repair. Mobilization of iris tissue from peripheral synechiae is illustrated later in Case Studies 1, 2, and 5.

Principle 2: Intraocular Suturing and Knot Tying

The second fundamental principle is the method for suturing iris and tying knots within the eye. Often the knot is central, and traction to bring the iris with the knot to a limbal wound will damage the iris repair. Figure 31-1 illustrates the basic technique for passing the suture into the anterior chamber via a paracentesis, through a radially oriented iris defect, and then out through the peripheral cornea on the opposite side of the paracentesis. In all cases, a nonbiodegradable suture material should be used. The most common suture employed is 10-0 polypropylene (Prolene). A long, gently curved needle is typically used. The Ethicon CIF-4 needle is strong and relatively easy to control. Although it has a noncutting needle tip, the bulk of the needle has the disadvantage of leaving a small new iris puncture defect in its path. Finer needles that create less of an iris defect but are correspondingly more difficult to handle are the Ethicon CTC-6 (curved) and STC-6 (straight).

  

 

Figure 31-1  A, Long needle enters through a paracentesis, across the iris defect, and exits by puncturing through the peripheral cornea. B, Hook such as a Kuglen hook retrieves a loop of the distal arm of the suture, making sure that the needle end of the suture remains external to the eye. C, Loop is now external through the paracentesis. D, Proximal end of the suture is wrapped around the suture loop twice, creating one throw of what will become the knot. E, Tension on each end of the suture draws the knot into the eye and tightens it. F, After four throws, the suture ends are cut with a thin sharp knife such as a Wheeler blade. (Technique credited to Steven Siepser, MD.)

 

 

A flaccid iris and a knot close to a wound may allow the surgeon to tie the knot at the limbus without undue iris damage. Successful completion of many cases of iris reconstruction requires that no additional traction be placed on the iris, however. The knot must be advanced into the eye and tied internally. One method to accomplish a knot deep inside the anterior chamber is to form the knot loop externally and then use a hook such as a Kuglen hook to advance the loop into the eye and make it snug. The procedure is repeated three or four times, achieving a secure knot at completion. The disadvantage of this technique is that it requires a skilled assistant, as it is necessary to maintain gentle traction on each of the suture ends while simultaneously advancing the knot with the hook. Three skilled hands are, therefore, needed.

Figure 31-1 illustrates an alternative two-handed technique popularized by Stephen Siepser, MD. In this variation, the knot is tied by passing loops externally, but the two ends of the suture can then be tightened, which draw the knot internally into the eye. This technique is elegant and does not require the third hand of a skilled assistant. A second throw is typically placed. In the original description by Seipser, the second throw creates a “granny” knot. Osher teaches a true locking knot in which the second throw is passed either in mirror image of suture orientation or in the opposite direction around the suture loop to create a more “square” locking knot.[5] Once the knot is tied, the suture may be cut using micro scissors through an unenlarged paracentesis, or with Vannas' scissors through a slightly enlarged limbal incision.

Principle 3: Reattachment of Iris to Sclera

The third principle is the technique for repair of a peripheral iris defect with the use of horizontal mattress sutures. A double-armed suture is employed. The mattress suture brings the iris back to its origin, if possible (Figure 31-2), or closes a peripheral defect using available adjacent iris tissue (Figures 31-3A and B). The knot is tied externally but then rotated below the surface so that only a smooth loop of external suture remains. By using this technique of suture rotation and burying the knot, identical to the concept used in transscleral suturing of secondary posterior chamber (PC) IOLs (see Chapter 41, Figure 41-2), only a smooth loop of suture material remains. A scleral flap does not need to be dissected, and conjunctiva alone provides adequate coverage of the suture material. Alternatively, if it is desired that both suture material and knot lie below the scleral surface, then creating a scleral groove with a beaver blade before placement of the sutures can be helpful. This allows the suture material to lie in a trench beneath the scleral surface when the knot is tied. The knot can similarly be rotated into the sclera. A large iridodialysis will require several adjacent horizontal mattress sutures. The size of each suture “bite” of iris should be about 1½ clock hours.

  

 

Figure 31-2  A and B, Iridodialysis is repaired with one or more mattress sutures of double-armed 10-0 polypropylene sutures tied externally under a conjunctival flap. Both arms of the polypropylene suture are introduced through a paracentesis opening on the opposite side of the anterior chamber. The dialyzed edge of iris is engaged by each needle in turn, and the needle is passed through the sclera. C, Mattress suture is tied. D, Knot is rotated below the surface of the sclera, preventing later suture erosion through the conjunctiva. E, Conjunctival flap is then closed over the polypropylene mattress suture with corner sutures of 8-0 Vicryl or other absorbable suture material.

 

 

  

 

Figure 31-3  A, Conjunctival flap is recessed in the area of a sector iris defect. B, Horizontal mattress sutures bring midperipheral iris tissue into the basal area without iris. C, Interrupted sutures close the midperipheral space. DF, “Sphincterotomies” in the central zone create a new pupillary aperture.

 

 

A large defect may require a combination of these techniques (see Figure 31-3). Typically the repair begins by using horizontal mattress sutures to create as much coverage of the peripheral and midperipheral cornea as possible (see Figures 31-3A and B). Often, this results in a distortion of the pupil itself (see Figure 31-3C). A new pupil is constructed by judicious incisions in the iris and placement of additional sutures (see Figures 31-3C–F). Case Studies 3 and 4 particularly illustrate these techniques. The iris is highly visible in some individuals and often important to the patient cosmetically.

In general, the surgeon should err on the side of leaving a pupil too small rather than too big. Postoperatively, a surgeon can use the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser to expand the pupil by performing sphincterotomies with Nd:YAG laser pulses. The technique is similar to peripheral iridectomies with the Nd:YAG laser. A focusing contact lens is helpful. The laser setting is typically 6 mJ.

Principle 4: Pupil Repair

Blunt trauma often causes injury to the iris sphincter. An isolated rupture of the sphincter muscle is repaired with single interrupted sutures, similar to the technique illustrated in Figures 31-1 and 31-2. Case Study 1 illustrates the repair of local sphincter damage with interrupted sutures. When there is more generalized damage to the iris sphincter, caused by either multiple ruptures or ischemia, a different technique is needed. The surgeon can generally determine by careful preoperative inspection whether generalized iris sphincter injury has occurred. At the slit lamp examination, while varying the illumination through the pupil, the surgeon can inspect whether there is reactivity of the iris sphincter. In addition, the iris sphincter architecture is carefully inspected. When the iris sphincter architecture is not preserved and there is little to no reactivity, then a larger-scale repair of the pupil is needed.

The surgeon has two choices. The simpler choice is to place multiple interrupted sutures. This will typically result in a square or diamond-shaped pupil (Figure 31-4). Although cosmetically suboptimal, the optical benefit to the patient is substantial.

    

 

Figure 31-4  A, Diamond-shaped appearance of the pupil after four interrupted sutures reduced a large atonic pupil at the time of penetrating keratoplasty. B, High magnification shows the four polypropylene suture knots.

 

 

Alternatively, the surgeon can perform a 360° purse-string suture. This procedure was originally demonstrated by Dr. Pius Bucher of Austria and is illustrated in Case Study 6. The placement of the suture occurs after the completion of any cataract removal and IOL placement, of course. In the iris cerclage purse-string suture technique, a 10-0 Prolene suture on a CTC-6 needle (Ethicon) is recommended. In addition to the larger principal incision used for the cataract and IOL surgery, the surgeon should place two or three paracentesis openings at approximately equally spaced intervals. The needle is introduced through the principal incision and is passed in and out of the midperipheral iris stroma, typically for three or four passes. The needle is then passed out of the paracentesis by “docking” the needle tip into the end of a blunt 27-gauge irrigating cannula that has been passed through the paracentesis into the anterior chamber. In this manner, the pointed needle can be externalized without engaging the corneal tissue around the paracentesis. The needle is then regrasped with the needle holder and reintroduced into the eye, repeating the process for another quadrant or third of the iris. In reintroducing the needle through the paracentesis, great care must be taken not to inadvertently engage the lip of Descemet's membrane or any of the stroma. It is of great help during needle reintroduction to wiggle and side-sweep the needle tip while advancing the needle within the paracentesis to ensure that no corneal stromal fibers are engaged. If the surgeon encounters difficulty passing the tip of the needle through the paracentesis cleanly, placement of some viscoelastic in the paracentesis can be a great aid in opening the passageway.

In one approach the bites of the cerclage suture are placed in the midperipheral iris, not close to the pupillary margin. The reason is that, once the suture is tightened, the suture between each of the bites will tighten and constrict. If the suture bites are near the pupillary edge, the suture material will be pulled into the pupillary opening, resulting in scalloping and a petalloid appearance to the pupil border. In contrast, if the suture material is kept in the midperiphery, the suture material itself will not be able to cross over the pupillary zone itself. In an alternate approach, the sutures bite are passed near the sphincter margin in a “spiral or baseball” stitch fashion in which the majority of the bites are placed through the iris tissue from the underside, then the needle tip is wrapped around the pupil margin and the next bite is taken. Both approaches result in an excellent cosmetic and functional result. If there is any difficulty controlling the passage of the needle through the iris tissue, micro forceps, such as those used for bi-axial microincision surgery, introduced through a paracentesis may be helpful by grabbing iris tissue during the needle pass.

After completing the 360° passage of the suture, the knot is carefully tied through the principal limbal incision. Alternatively, the needle can be passed out through a paracentesis, and the suture tied through the main incision using the Siepser sliding knot technique. The pupil is drawn down to a size of 3–4 mm, which is a good compromise between cosmetic and functional result, and fundus visualization. During knot tying, pulling on the suture ends often results in a smaller than desired pupil size, and it is often helpful to deliberately start with a pupil size that is larger than required, and then draw it down to size, The postoperative appearance of the pupil is usually circular or only slightly irregular.

If a major retinal problem occurs subsequently, such as retinal detachment, the iris cerclage suture can be released with either laser spots or intraoperatively by cutting the suture.

Adjunctive pupil repair techniques are useful in situations where the pupil is distorted or eccentric. Pupil distortion and ovalization may occur resulting from trauma itself, or sometimes after repair of an iris dialysis. This may be remedied by the strategic placement of an interrupted suture to the pupil margin, with or without pupil sculpting techniques to round it off. Pupil reshaping may be achieved with a vitrector on the lowest available cut rate and moderate vacuum, or by using intraocular scissors. If the pupil is markedly eccentric, the pupil may be translocated by opening up a new pupil in the center with a vitrector, and closing the peripheral one with one or more interrupted sutures.

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Case studies in iris reconstruction

Case 1: traumatic mydriasis caused by localized sphincter rupture

This patient had blunt trauma from a paintball gun injury, resulting in cataract and traumatic mydriasis (Figure C1-1). Preoperative slit-lamp examination showed that the sphincter muscle had ruptured temporally with atrophy of the sphincter in that region and that the remainder of the sphincter muscle reacted normally to light. After cataract surgery and IOL implantation, a Y-hook was used to bring the iris tissue out of the angle (Figure C1-2). Repair of the temporal iris consisted of placing two interrupted 10-0 polypropylene sutures (Figures C1-3–C1-6, surgeon's view temporally). One day after surgery, a reasonably well-centered pupil was present, centered over the IOL (Figure C1-7, slit-lamp view).

  

 

Figure C1-1 

 

 

  

 

Figure C1-2 

 

 

  

 

Figure C1-3 

 

 

  

 

Figure C1-4 

 

 

  

 

Figure C1-5 

 

 

  

 

Figure C1-6 

 

 

  

 

Figure C1-7 

 

 

Case 2: airbag injury

A severely eccentric pupil and cataract resulted from an airbag injury in a motor-vehicle accident. The iris appeared absent inferotemporally (Figure C2-1). Preoperative gonioscopy showed that the iris appeared bunched up into the angle of the area corresponding to the pupil abnormality (Figure C2-2). The surgical photos are from the surgeon's perspective, sitting superiorly. At surgery, the severely subluxated lens had been removed by pars plana lensectomy and vitrectomy (Figure C2-3). A posterior chamber IOL with a 7 mm optic was secured through transscleral sutures, deliberately decentered in the direction of the pupil deformity in case the pupil cannot be fully shifted centrally (Figure C2-4). Repair of the iris began with traction on the peripheral iris to release adhesions, taking care to avoid dialysis of the iris root (Figures C2-5–C2-7), markedly improving the amount of peripheral iris tissue, but leaving a nonreactive pupil that was still large enough to cause glare (Figure C2-8). A single interrupted suture across the inferotemporal pupil (Figure C2-9) reduced the pupil to an acceptable size and shape (Figure C2-10).

  

 

Figure C2-1 

 

 

  

 

Figure C2-2 

 

 

  

 

Figure C2-3 

 

 

  

 

Figure C2-4 

 

 

  

 

Figure C2-5 

 

 

  

 

Figure C2-6 

 

 

  

 

Figure C2-7 

 

 

  

 

Figure C2-8 

 

 

  

 

Figure C2-9 

 

 

  

 

Figure C2-10 

 

 

Case 3: sector iris defect after melanoma excision

A slowly expanding iris melanoma, observed and documented for over a decade, threatened to invade the angle in a patient with developing cataract (Figures C3-1 and C3-2). The surgeon sat superiorly (Figure C3-3) to have a better angle of access for excising the tumor after phacoemulsification cataract extraction and capsular bag placement of a PC IOL in this right eye.

  

 

Figure C3-1 

 

 

  

 

Figure C3-2 

 

 

  

 

Figure C3-3 

 

 

The melanoma was isolated first with radial incisions by a Gills-Vannas scissors, with a small margin of normal iris (Figures C3-4 and C3-5). The basal iris was excised as close as possible to the angle using horizontal vitreous scissors (Figures C3-6 and C3-7) and the tumor placed on a sterile tongue blade (Figure C3-8) to maintain a flat orientation for pathologic examination.

  

 

Figure C3-4 

 

 

  

 

Figure C3-5 

 

 

  

 

Figure C3-6 

 

 

  

 

Figure C3-7 

 

 

  

 

Figure C3-8 

 

 

The reconstruction began with a 10-0 polypropylene suture reapproximating the sphincter edges (Figures C3-9 and C3-10). Note how much larger the defect became because of relaxations of the iris, compared with the original area of excision (Figure C3-4). A second suture added reinforcement (Figures C3-11 and C3-12), but it became apparent that a large basal defect would persist that, given the exposed inferior location, would be a source of glare.

  

 

Figure C3-9 

 

 

  

 

Figure C3-10 

 

 

  

 

Figure C3-11 

 

 

  

 

Figure C3-12 

 

 

To close the basal defect, a double-armed 10-0 polypropylene suture was passed in a horizontal mattress orientation (Figures C3-13 and C3-14) through the iris and the limbus, which closed the basal defect when tied (Figure C3-15). The knot was rotated beneath the scleral surface to prevent later erosion through the conjunctiva (Figure C3-16).

  

 

Figure C3-13 

 

 

  

 

Figure C3-14 

 

 

  

 

Figure C3-15 

 

 

  

 

Figure C3-16 

 

 

As a consequence, the pupil was shifted eccentrically. Two additional sutures closed the eccentric opening (Figures C3-17 and C3-18), restoring a nearly round and well-centered pupil (Figure C3-19). The appearance on the first postoperative day showed a somewhat small pupil (Figure C3-20), but the patient had no complaints of dark vision. It is better to err on the side of leaving the pupil too small at the time of the surgical repair, as later expansion of the pupil can be achieved easily with laser sphincterotomies (see Chapter 52) and/or lysis of a suture.

  

 

Figure C3-17 

 

 

  

 

Figure C3-18 

 

 

  

 

Figure C3-19 

 

 

  

 

Figure C3-20 

 

 

Case 4: iris loss at cataract surgery

This patient experienced iris prolapse and subsequent bleeding from the iris root during an attempted implantation of a phakic IOL for the correction of high hyperopia. A secondary cataract developed, and uncomplicated cataract surgery with PC IOL implantation was performed. The patient complained about severe glare postoperatively resulting from exposure of the IOL edge (Figure C4-1). An artificial prosthetic iris was recommended, but the patient was unhappy with the prospect of implantation of an investigational device and sought other surgical remedies.

  

 

Figure C4-1 

 

 

From the surgeon's perspective seated superiorly (Figure C4-2), the first area to be addressed was the loose stub of iris tissue. A double-armed 10-0 polypropylene suture was passed as a horizontal mattress closure (Figures C4-3 and C4-4) that provided partial coverage when the suture was tightened (Figure C4-5).

  

 

Figure C4-2 

 

 

  

 

Figure C4-3 

 

 

  

 

Figure C4-4 

 

 

  

 

Figure C4-5 

 

 

The inferior pupil appeared to be too superior after the horizontal mattress suture, and an inferior sphincterotomy was performed with Gills–Vannas scissors (Figure C4-6). The superior gape was closed with two interrupted sutures (Figures C4-7–C4-9). The pupil appeared too small, with a vertical slit configuration. Small sphincterotomies were then placed horizontally to the left and to the right (Figure C4-10).

  

 

Figure C4-6 

 

 

  

 

Figure C4-7 

 

 

  

 

Figure C4-8 

 

 

  

 

Figure C4-9 

 

 

  

 

Figure C4-10 

 

 

At this point, the original inferior sphincterotomy shown in Figure C4-6 appeared excessive, with exposure of the inferior edge of the capsulorrhexis margin (Figure C4-11). The exposure was remedied with an interrupted suture (Figure C4-12). Postoperatively, the patient reported elimination of the glare and was pleased by the improvement in the appearance of her highly visible iris (Figure C4-13). The upper lid in its natural position covered the remaining superior peripheral iris defect.

  

 

Figure C4-11 

 

 

  

 

Figure C4-12 

 

 

  

 

Figure C4-13 

 

 

Case 5: anterior chamber intraocular-lens-induced pupillary distortion

The patient was experiencing both severe glare and loss of vision caused by cystoid macular edema associated with iris tuck 6 months after secondary implantation of flexible open-loop anterior chamber IOL. The view of the surgeon sitting superiorly is shown in Figure C5-1. Simple removal of the misplaced haptics that caused the iris tuck did not relieve the pupillary distortion (Figure C5-2).

  

 

Figure C5-1 

 

 

  

 

Figure C5-2 

 

 

After thorough vitrectomy and placement of a transscleral suture-fixated PC IOL, traction on the peripheral iris released some peripheral synechiae (Figure C5-3). Next, the large iridectomy was closed with a single interrupted suture (Figure C5-4).

  

 

Figure C5-3 

 

 

  

 

Figure C5-4 

 

 

The pupillary aperture was then reduced with interrupted sutures nasally and temporally (Figures C5-5 and C5-6). To create a rounder pupil, small sphincterotomies were added inferiorly (Figure C5-7) and superiorly (Figure C5-8). On the first postoperative day, the view was mildly hazy because of the inflammatory reaction, but the slit-lamp appearance showed a reasonably sized central pupil (Figure C5-9). Over 3 months the cystoid macular edema resolved with improvement of best-corrected visual acuity and full relief from glare.

  

 

Figure C5-5 

 

 

  

 

Figure C5-6 

 

 

  

 

Figure C5-7 

 

 

  

 

Figure C5-8 

 

 

  

 

Figure C5-9 

 

 

Case 6: atonic pupil corrected with iris circlage purse-string suture

This patient requiring cataract surgery had a lifelong history of isolated bilateral atonic pupils that measured 8 mm without dilation and nonreactive to light. His clinical presentation is more commonly seen after blunt trauma leading to generalized atrophy of the sphincter muscle. Glare symptoms will be worsened after cataract surgery because the IOL optic edge will not be covered by iris.

The appearance of the pupil at the start of surgery is shown in Figure C6-1. The appearance after completion of phacoemulsification and PC IOL implantation through a temporal clear corneal incision is shown in Figure C6-2. Two additional paracentesis openings were made at 4 o'clock and 8 o'clock positions relative to the principal incision (120° spacing).

  

 

Figure C6-1 

 

 

  

 

Figure C6-2 

 

 

A 10-0 polypropylene suture on a CTC-6 (Ethicon) needle initially made three full-thickness bites in the midperipheral iris (Figure C6-3), moving from the principal incision toward the first paracentesis. For the needle tip to exit the paracentesis without engaging any corneal tissue, a blunt-tip 27-gauge cannula was inserted into the anterior chamber, and the needle tip “docked” inside the cannula (Figure C6-4). The needle and cannula were then externalized as a unit (Figure C6-5). The needle was reinserted through the paracentesis, taking care to make sure that no corneal tissue was engaged, and the purse-string iris suture technique was repeated in each remaining sector, ending at the original incision (Figures C6-6 and C6-7).

  

 

Figure C6-3 

 

 

  

 

Figure C6-4 

 

 

  

 

Figure C6-5 

 

 

  

 

Figure C6-6 

 

 

  

 

Figure C6-7 

 

 

The suture ends were then tied externally, and the knot was advanced into the eye with a Kuglen hook while the surgeon and assistant maintained gentle tension on each suture end (Figure C6-8). After four throws, the suture ends were cut with a Gills–Vannas scissors, leaving a central, normal-sized pupil (Figure C6-9).

  

 

Figure C6-8 

 

 

  

 

Figure C6-9 

 

 

Postoperatively, the appearance of the pupil was grossly normal, for the first time in the patient's life (Figure C6-10). High-magnification inspection revealed two barely visible strands of the polypropylene suture across small gaps in the gathered-up iris (Figure C6-11). Although this is of no optical consequence, it illustrates the importance of placing the suture bites in the midperipheral iris rather than near the sphincter edge. Suture bites near the sphincter margin will result in more gaps with exposed suture and a more irregularly bordered pupil.

  

 

Figure C6-10 

 

 

  

 

Figure C6-11 

 

 

Case 7: preservation of iris

This complex multistep case is presented in summary form to illustrate the critical importance of never sacrificing iris tissue that may be salvaged for reconstruction. This 37-year-old man suffered massive accidental blunt trauma that ruptured the superior limbus and dialyzed all iris attachments except 2–3 clock hours inferiorly. Emergency repair closed the superior wound with iris prolapse covered by conjunctiva and no visible pupil (Figure C7-1). The patient was referred for repair.

  

 

Figure C7-1 

 

 

At surgery, a conjunctival flap was dissected back, exposing a large amount of prolapsed iris tissue (Figure C7-2). Viscoelastic agent infusion separated the iris pillars, revealing the original pupillary space (Figure C7-3). The iris pillars were reattached to the sclera with multiple, horizontal, mattress, double-armed sutures (Figures C7-4 and C7-5).

  

 

Figure C7-2 

 

 

  

 

Figure C7-3 

 

 

  

 

Figure C7-4 

 

 

  

 

Figure C7-5 

 

 

The result was a marked improvement, particularly in the critical areas inferiorly, nasally, and temporally, where most glare originates (Figure C7-6). If glare proves to be a problem, despite any maximal reconstruction of available iris, then subsequent implantation of a prosthetic iris device can be considered.

  

 

Figure C7-6 

 

 

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Iris prostheses

Every effort should be made to reconstruct the natural iris. However, some patients do not have adequate residual iris tissue to prevent glare and other optical aberrations. In general, iris prosthesis is required when more than a quadrant of iris tissue is missing. Iris defects spanning less than 3 clock hours can usually be repaired with imbrication suture techniques, such as those described earlier in this chapter. In some patients, although iris tissue is not actually missing, the quality of the iris stroma present may be too poor to function properly and to repair. Examples include the iris in uveitic patients or iridocorneal endothelial (ICE) syndrome. Similarly, in patients with ocular albinism, the pigment layer can be either transparent or highly dysfunctional, depending on whether the patient is tyrosinase positive or negative. Under these circumstances, the surgeon has two principal options. The first is to attempt to fit the patient with a “narcissus” contact lens with an “artificial iris” peripheral pigmentation painted on it. Some patients have been greatly helped by these devices, but these lenses are expensive and need periodic replacement. In the absence of the contact lens, the patient has a return of the visual impairment.

Alternatively, IOL and polymer technology have permitted the development of pigmented materials that can be permanently implanted as iris prostheses within the eye.

The artificial iris implant was first introduced and published in Europe by Sundmacher, Reihnhard, and Althaus[6–8] in 1994. They reported using a single-piece black diaphragm IOL in cases of traumatic or congenital aniridia. The first use of small-incision artificial iris ring implants was reported at the Welch (Man named Welch) Cataract Congress by Kenneth Rosenthal in 1996. Subsequently, two independent series of cases have been reported, demonstrating the safety and efficacy of both the single-piece black diaphragm IOL and the endocapsular prosthetic iris rings.[9,][10]

When contemplating use of a prosthetic iris device, the surgeon must first define the clinical situation and choose the appropriate device based on the relevant anatomy. Currently there are two main categories of prosthetic iris implant available, each with specific indications.

The single-piece black diaphragm IOL (Figure 31-5) available from Morcher GmbH provides a full iris diaphragm and IOL that can be placed in the ciliary sulcus on capsular support or transsclerally sutured. However, a significant drawback of the single-piece diaphragm IOL is that it requires a relatively large incision size, which is associated with delayed visual rehabilitation, increased astigmatism, and increased risk of intraoperative suprachoroidal hemorrhage. When implanting the Morcher single-piece iris diaphragm IOL, care must be taken while manipulating the haptics, because they are brittle and easily broken. Other manufacturers, such as Ophtec BV, also produce single-piece diaphragm IOLs, and these are available in a variety of colors in an attempt to more closely match that of the native iris. The colors available are light blue, light green, mid brown and black. The Ophtec model 311 requires a slightly smaller 9 mm incision than the 10 mm for the Morcher implant, and also has haptics that are less susceptible to fracturing. The black IOL is made of a polycarbonate material, while the other colored IOLs are made of polymethyl methacylate (PMMA). The Morcher device has a 5 mm aperture, while the Ophtec device has a 4 mm “pupillary” opening. They also differ in edge configuration of the optic. The Morcher 67-series devices have a squared-edged optic fused to the black carrier material, while the Ophtec 311 device's optic has a round edge which is inset into a rounded notch in the carrier device.

  

 

Figure 31-5  Intraocular lens (IOL) with a peripheral pigment skirt for cases of aniridia or other generalized absence of iris tissue. Implantation of this large IOL requires an incision of at least 10 mm.

 

 

Morcher GMBH has recently introduced a 30-B series that consists of a clear PMMA diaphragm backbone with an opaque, colored film applied to the anterior surface (see Figure 31-6). The colors are merged from pixilated multicolored dots within the film (see Figure 31-7). This far, one case in the US has been presented by Sam Masket, MD at ASCRS, San Francisco 2009.

  

 

Figure 31-6  The Morcher 30-B device has an opaque, colored film (seen on edge here) applied to the PMMA backbone.

 

 

  

 

Figure 31-7  The Morcher 30-B device is seen here at low mag (left) and high mag (right). Note the appearance of the colored flecks under low mag which blend to create the desired effect when viewed with the naked eye.

 

 

Another category of iris prosthetic devices is designed specifically for endocapsular fixation. One type currently available is the Morcher 50-series endocapsular rings with iris diaphragm designed around a standard capsular tension ring, developed by Volker Rasch of Potsdam, Germany. The other endocapsular device is the Iris Prosthetic System (IPS) from Ophtec BV. Neither of these endocapsular aniridia devices have an optical portion and, therefore, can be inserted through a small incision. Slight enlargement of the incision may be necessary, depending on the specific implant chosen. The Morcher 50-C can be placed through a 3 mm incision, while the 50D, E, or F may require a slightly larger incision depending on the desired pupil size. The Ophtec “IPS” multipiece device requires an approximately 5 mm incision.

There are two styles of Morcher iris endocapsular ring devices. One style consists of a ring with a single fin (Type 96F) and is used for sectoral iris atrophy or loss, and each fin will cover up to 3 clock hours of loss (Figure 31-8). Two or more rings may be used to cover larger defects. The other style consists of two rings, each with multiple fins that interdigitate (Morcher Types 50C, D, E, and F), and are used to create a full iris diaphragm (Figure 31-9). The Type 50C rings produce an iris diaphragm with a pupil size of approximately 6 mm, which reduces the stray light entering the eye by 75% yet provides an aperture compatible with excellent fundus viewing postoperatively. If a smaller pupil size is desired, newer models 50D, E, and F are available with pupil sizes of 4, 3.5, and 4 mm respectively. The 50F device has less space between the interdigitating fins, making alignment of the two pieces more facile.

  

 

Figure 31-8  Segment of single-fin opaque implant for blocking a sector defect.

 

 

  

 

Figure 31-9  Implantation of two multiple-fin segments that are aligned to obtain 360° artificial iris coverage through a small incision.

 

 

  

 

Figure 31-10  The Ophtec IPS multi-piece device is seen here in situ within the capsular bag with the two elements and central locking ring with 3 mm aperture in place. A CTR and PCIOL are also within the capsule.

 

 

If the 50C rings are chosen, the foldable optic chosen should have a diameter of 6.5 mm to eliminate edge glare, while a standard 6 mm lens optic is acceptable for models 50D, E, and F. When placing the IOL, the ideal optic position is posterior to both iris rings. An additional 0.5–1.0 diopter of optic power should be added to the initially calculated IOL, since the optic sits more posteriorly in the more crowded capsular bag.

After implantation, the artificial iris rings remain quite stable and the tension ring component of the aniridia ring can lend support to the capsule by distributing zonular tension evenly around the equator of the capsular bag.

Caution should be exercised when implanting these devices because they are brittle and susceptible to fracture. When planning for surgery with the endocapsular ring type iris implants, it is advisable to order an extra piece in case a ring is fractured during surgical manipulation. Furthermore, the capsular bag can become somewhat crowded after three devices have been inserted. Finally, great care must be taken not to damage the fragile capsule of patients with congenital aniridia.

The Ophtec IPS consists of modular units designed to be implanted in-the-bag (Figure 31-10). This is available in the same variety of colors being offered in its range of Model 311 full-sized aniridia implants. The IPS modular device includes the bilobed elements, which, when assembled, re-establishes an intact diaphragm, a capsular tension ring, and a locking element to secure the implant once the device has been assembled in the bag. The surgeon has to be gentle during the assembly and locking of the device, as it requires a fair amount of manipulation within the capsular bag.

While the black iris devices improve optical function without any improvement in cosmesis, the other colored devices made by Ophtec BV go one step further to achieve a better cosmetic match with the native iris of the fellow eye. Although this is an improvement, the result may still be suboptimal, because only a single shade is available for each color, which when applied evenly to the entire iris surface, leads to a flat, two-dimensional, untextured unnatural iris appearance, even if the color shade were an exact match to the fellow. Morcher now offers multiple shade colored iris prostheses.

  

 

Figure 31-11  This slit lamp photo shows a patient who had an iridociliary melanoma resected, leaving an inferonasal iris defect and profound glare. At the time of cataract surgery, a Humanoptics custom iris device was placed into the capsular bag with a PCIOL and a CTR. Her glare was completely eliminated.

 

 

    

 

Figure 31-12  This Humanoptics custom iris prosthesis was matched to the vestigial iris stump in this 4-year-old congenital aniric with dense cataract. The device is trephinated to the size of the capsular bag (left), then implanted in-the-bag with a PCIOL. Note the difference in appearance of the device after implantation. The more blue appearance of the residual iris stroma is artifactually altered by trypan blue used during the capsulorrhexis for visualization of the prosthesis during implantation of the device.

 

 

    

 

Figure 31-13  This Humanoptics iris device is inserted with forceps. Note the apparent iris detail (right).

 

 

A new iris implant has been designed to address this problem. Dr. Schmidt Inraocularlinsen has developed an iris implant made of a flexible material that may be custom tailored to be an exact match with the fellow iris. This extremely flexible device may be rolled up into a cylinder for insertion through a small cataract incision. Each iris device is meticulously crafted to match its fellow in color and shade as well as texture for a remarkably natural appearance. The manufacturer requires an anterior segment photograph to be taken of the fellow eye for this matching to be done.

This device is designed to be attached to the scleral wall with horizontal mattress sutures being passed through the peripheral silicone material itself, in a similar fashion to the method used to repair an iridodialysis. The device is quite flexible in its deployment, as the material may be cut to size with a corneal trephine to match the corneal diameter, or with scissors to the desired shape and size. If only a sector defect needs to be repaired, it is possible to suture the implant after being cut to size, to the remaining normal iris tissue. Further research is being carried out in this area to assess the suitability of this implant for in-the-bag fixation without sutures.

The technology for iris reconstruction will continue to improve as several groups are working on other prosthetic iris devices. In the future we can expect refinements in structure, flexibility, and implantation techniques.

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References

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[2]. Weidenthal D.T.: Experimental ocular contusion.  Arch Ophthalmol  1964; 71:77-81.

[3]. Wolff S.M., Zimmerman L.E.: Chronic secondary glaucoma associated with retrodisplacement of iris root and deepening of the anterior chamber angle secondary to contusion.  Am J Ophthalmol  1962; 54:547-563.

[4]. Paton D., Craig J.: Management of iridodialysis.  Ophthalmic Surg  1973; 4:38-39.

[5]. Osher R.H., Snyder M.E., Cionni R.J.: Modification of the Siepser slip-knot technique.  J Cataract Refract Surg  2005; 31:1098-1100.

[6]. Reihnhard T., Sundmacher R., Althaus C.: Irisblenden-IOL bei traumatischer aniridie.  Klin Monatsbl Augenheilkd  1994; 205:196-200.

[7]. Sundmacher R., Reihnhard T., Althaus C.: Black diaphragm intraocular lens for correction of aniridia.  Ophthalmic Surg  1994; 25:180-185.

[8]. Sundmacher R., Reihnhard T., Althaus C.: Black diaphragm intraocular lens in congenital aniridia.  Ger J Ophthalmol  1994; 3:197-201.

[9]. Thompson C.G., Fawzy K., Bryce I.G., et al: Implantation of a black diaphragm intraocular lens for traumatic aniridia.  J Cataract Refract Surg  1999; 25:808-813.

[10]. Osher R.H., Burk S.E.: Cataract surgery combined with implantation of an artificial iris.  J Cataract Refract Surg  1999; 25:1540-1547.