25.1 Introduction

Iris and pupillary defects may result from a variety of causes, ranging from congenital conditions, such as aniridia, to traumatic iris loss. Here is a list of the etiology of iris and pupillary defects:

• 
  

  Trauma.

  
  
• 
  

  Congenital.

  
  
• 
  

  Postsurgical.

  
  
• 
  

  Post-acute-angle closure or elevated intraocular pressure (IOP).

  
  
• 
  

  Inflammatory (chronic uveitis).

  
  
• 
  

  Infectious (herpes simplex virus [HSV], herpes zoster virus [HZV]).

  
  
• 
  

  Proliferative (iridocorneal endothelial [ICE] syndrome, epithelial downgrowth).

These defects are often managed in conjunction with cataract surgery and intraocular lens (IOL) implantation. Patients with iris defects can be debilitated by glare and photophobia, and there may be a psychological burden due to the cosmetic discrepancy between the eyes. It is helpful to document and grade the indication and severity of photophobia prior to surgery (Table 25-1). Optically, a dilated pupil may induce increased aberrations and degrade visual quality. It is also important to note that patients who may have developed a dense cataract after trauma may not report significant photophobia preoperatively, but may develop symptoms after the cataractous lens is removed and replaced with an IOL. Furthermore, if there is insufficient iris overlap over the edge of an IOL optic, patients may report halos or arc light phenomena or monocular diplopia.

Repair of these iris and pupillary defects requires a combination of visual, functional, and cosmetic considerations. The goal of iris repair is to close the iris defect(s) sufficiently to prevent excess light from passing through outside the pupil, and/or to reduce a dilated or atonic pupil to a more physiological size, better matching the patient’s other eye. Depending on the preoperative iris muscle function (which is often impaired) and/or suturing technique, the pupil may be minimally reactive postoperatively.

25.2 Surgical Management of Iris Defects

Preoperative preparation is key in determining the appropriate approach, instrumentation, and devices required to manage iris and pupillary defects. One must consider the quantity and the quality of the remaining iris tissue in place to repair the defect. This first consideration is whether the iris abnormality can be repaired using iris suturing alone, using an iris prosthesis, or using both (Table 25-2). Iris prosthetic devices are discussed in Chapter 26. With the exception of specific color-matched iris prostheses, most prostheses are black and thus are not as cosmetically pleasing as primary iris repair. Iris suturing of existing iris tissue is preferred whenever adequate iris tissue is present. Cases where a new proliferative membrane formation has caused the iris defect (iridocorneal endothelial syndrome, rubeosis iridis, or epithelial downgrowth), or congenital iris defects generally have poor iris tissue quality, and the remaining iris tissue invested within the membrane is often fibrosed. These defects are best repaired using a prosthetic iris. On the other hand, traumatic iris defects generally respond well to iris suturing techniques.

There are three broad settings in which iris suturing is required; each requires its own approach to iris repair:

• 
  

  Is the main issue a dilated/atonic pupil? Is it focal or complete?

  
  
• 
  

  Is the main issue a focal iris defect? Is there some iris loss or is this an iris coloboma?

  
  
• 
  

  Is the main issue an iridodialysis? How large?

A basic flow sheet for surgical planning is described in Fig. 25.1. One must consider the size and nature of the iris defect, as well as determine whether there is a single defect or whether multiple defects are present. It should be determined whether the defect is sectoral in nature, or if the pupil is uniformly fixed in a dilated position. Sectoral defects are very amenable to interrupted sutured iris techniques. Pupils that are uniformly dilated can be managed by either iris cerclage techniques, or by interrupted iris sutures in combination with intraoperative thermal pupilloplasty or postoperative laser pupilloplasty.

The recommended instrumentation for iris suturing includes the following:

• 
  

  Needle driver.

  
  
• 
  

  Kuglen hook.

  
  
• 
  

  Micrograspers.

  
  
• 
  

  Microtying forceps.

  
  
• 
  

  Microscissors.

  
  
• 
  

  10–0 polypropylene on CIF-4 needles (Ethicon).

Generally speaking, patients with brown, dark irides have iris tissue that is much more resilient to iris suturing and often do well with these techniques if there is adequate iris tissue remaining. For one’s first few cases of sutured pupilloplasty, we recommend starting with patients with thick, brown irides. On the other hand, patients with very thin, light blue irides can have very thin tissue that can be unforgiving intraoperatively, and these patients should preferably be attempted after the surgeon is comfortable with the suturing techniques for iris repair. The risk of causing new intraoperative, iatrogenic iris defects is substantially higher in these patients. These patients should be counseled about this, and a backup iris prosthesis is useful to have available in the operating room at the time of iris repair in cases with light blue irides.

25.2.1 Siepser Knot and Modifications

The Siepser knot technique (described here) can be used for interrupted sutured pupilloplasty, works very well with sectoral iris defects, and can also be used for fixating a three-piece IOL to the iris. When used alone for managing an atonic dilated pupil, it can leave a “cat’s eye” appearance unless augmented with intraocular bipolar thermal pupilloplasty, which will be described later. The original technique was described by Siepser ¹ and more recently modified by Osher to allow for locking slip knots. ² Since then we have modified this technique (Video 25.1). A major benefit of this technique is that, as the knots are tied down, there is minimal displacement of the iris tissues.

Two corneal paracenteses are created along the trajectory of the needle. When passing the needle through the paracentesis, a slow, side-to-side swaying motion is performed as the needle tip enters and clears the paracentesis. This ensures that no corneal stromal fibers are engaged by the needle during the pass; otherwise it becomes impossible to retrieve a loop of suture later on. Iris micrograspers are used to stabilize the edges of the iris defect during the suture pass (Fig. 25.2 a). The sharp end of the needle is docked with a 27-gauge bent cannula and externalized through the proximal paracentesis (Fig. 25.2 b). When releasing the needle from the driver, it is helpful to stabilize the needle in both paracenteses (Fig. 25.2 c) because this prevents unwanted movement of the needle within the anterior chamber and protects the corneal endothelium. With the needle in this position, the tip is regrasped with the drivers in a safe, controlled fashion to fully externalize the needle. The distal strand and proximal strand of suture are identified (Fig. 25.2 d). Using a Kuglen hook, a loop of the distal strand is retrieved and externalized through the proximal paracentesis, adjacent to the proximal strand. The free end of the distal strand loop is designated strand 1 and is identified by pulling on it and noticing no displacement of the iris (Fig. 25.2 e). It is key that the loops are not twisted together through their course through the anterior chamber and paracentesis. In the nondominant hand, a straight tyer grasps strand 1, and a triple throw is made around a pair of curved tyers held in the dominant hand. The curved tyers then grasp and pull the proximal end (strand 3) through the distal loop. Without releasing the proximal strand, the external part of the distal strand is grasped, and pulling on both ends cinches the knot. The Kuglen hook is used to retrieve another loop of the distal strand, and a reverse single throw is performed in a similar manner and is cinched down by pulling on both proximal and distal strands. The Kuglen is then used to retrieve a third loop of the distal strand, and a regular single throw is performed and cinched down. Intraocular scissors or an MVR blade is used to trim the ends of the knot.

Stay updated, free articles. Join our Telegram channel

Join