Pearl

An iris that has disappeared after a severe open-globe injury may indeed have been expelled. However, it is often invisible simply because it retracted from view. This is a condition that needs to be addressed early; otherwise the fibrinous membrane, pulling the iris back toward its root, may become a fibrotic one. With a forceps the surgeon can gently pull the iris toward the center, 360°. Once the membrane turned fibrotic, the only solution left is the implantation of an iris prosthesis.

48.2Surgical Technique

The most commonly used suture is a 10/0 (occasionally 9/0) polypropylene thread attached to a long straight (STC-6) or curved (CIF-4) needle.3 The former is rather difficult to handle since the target tissue is typically quite far from the paracentesis; the further the tip of the needle is away from the fulcrum at the limbus, the more a small movement on the outside will cause a large one inside (see Fig. 48.2).

8 mm

2 mm

4 mm

1 mm

Fig. 48.2 The needle-related difficulty of iris suturing. If the intracameral portion of the needle is 4 times as long as the portion external to the limbus, a 1 mm needle movement on the outside will result in a 4 mm movement of the needle’s tip – and in real life it is a three-dimensional issue. (The needle length is proportionally illustrated here)

3 Ethicon/Johnson & Johnson, New Brunswick, NJ, USA. The application of these sutures is described in this chapter.

Pearl

The iris has no wound and therefore does not heal. The surgeon should never leave the suture under tension so that it cheesewires; it must hold the iris “till the end of times.”

48.2.1 Iris Laceration4

•Enter the AC with the needle one side from the lesion (see Fig. 48.3). The entry point should be at some distance from the limbus.

•Pick up the iris on this and then on the other side of lesion; a single-armed suture suffices.

•Exit the AC central to the limbus on the other side of the lesion, with the location mirroring the entry point.

•Create a paracentesis over the lesion, roughly equidistant to the points of iris engagement.

–Once both are securely out, cut the needle free – but not before. Leave the thread long so that it can be used for a second suture if needed.

•Use a small vitrectomy forceps5 or a barbed6 needle to withdraw the suture threads.

•Carefully tie the suture with several knots, trim it,7 and release the iris.8

•Depending on the size of the lesion, multiple sutures may be necessary (see

Fig. 48.4).

4In the phakic eye it is advisable to inject a small amount of visco underneath the iris where the needle’s passage is expected, to avoid injuring the lens capsule (see Sect. 39.4).

5The jaws of the forceps cannot be opened if the suture is too close to the paracentesis (see Fig. 13.3); it must be the shaft of the forceps, not the jaws, that is inside the corneal opening – unless the paracentesis is made very long.

6Make the hook large enough not to lose the suture when you try to exit the AC with the needle.

7Leave a tiny part behind, do not trim it right at the knot.

8The iris is very elastic and in most cases will tolerate the stretching required for it to be drawn to the paracentesis upon tying the suture. If it does not, you can try to push down the cornea while typing/cutting the knot. The sliding knot does not work well because the iris is not fixed; the only other option is to use two paracenteses and repeatedly withdraw one thread for tying. This is a rather cumbersome and lengthy procedure.

a

b

Fig. 48.3 Schematic representation of suturing an iris laceration or coloboma. (a) The red ellipsis shows the site of the paracentesis through which the suture threads will be withdrawn. The black dots show the points of needle entry/exit in the cornea and the red dots the points where the iris is engaged. Surgeon’s view. (b) The same maneuver is shown on a cross-sectional view. The reason why the corneal entry (1) and exit (4) points are rather close to the iris engagement points (3, 4) is because the thread, illustrated by the dashed line in the AC, lies at an angle to the iris plane, not parallel with it. (Traditionally, corneal entry/exit points at the limbus are recommended; in such a case, however, the suture is difficult to capture since the corneal and iris engagement points are almost on the same frontal plane.) While this certainly makes the introduction of the suture more difficult with the straight needle, it makes the catching of the suture much easier. This is less important if the paracentesis is superior or temporal, but very important if it is nasal or inferior

48.2.2 Iridodialysis

•Open the conjunctiva in the proximity of the iris lesion.

•Use a double-armed suture. Create a paracentesis on the opposite side from the lesion (Fig. 48.5).

Fig. 48.4 A large inferior iris lesion more than 10 years after suturing. The sutures are still visible; a coloboma is also seen since the eye had a silicone oil fill before. An AC IOL has also been implanted at the time of iris reconstruction

1.5 mm

S

Fig. 48.5 Schematic representation of suturing an iridodialysis. The paracentesis is on the opposite side of the lesion. A double-armed needle is introduced, and the iris picked up close to its edge. The needles exit at ~1.5 mm from the limbus and the sutures are tied (see the text for more details; the needle length is proportionally illustrated here). The black dots show the needles’ engagement points in the iris and the gray ones the exit points in the sclera. S suture-thread

•As you enter the AC with the needle, make it absolutely sure that you go through the paracentesis, not the cornea; it is very easy with the sharp needle to pick up corneal tissue. Wiggle the needle: if it is inside the wound, it moves freely; if it is caught in cornea, it does not.