Iris Reconstruction Surgery

Iris Suture Techniques

McCannel first introduced the concept of suturing the iris within a contained anterior segment by retrieving needles from small incisions. In his initial description, a long needle on a 10-0 polypropylene suture was passed into the proximal and distal ends of the iris defect, guiding the needle tip out a distal paracentesis by docking into a cannula. Both suture ends are then retrieved through an additional paracentesis nearest the desired knot, and the knot is tied and cut flush to the surface. The knot and reapproximated iris tissue are then reposited. This procedure is repeated until all necessary sutures have been placed to close the defect sufficiently. This technique works best when the defect is reasonably peripheral, the iris tissue can be stretched, and the knot does not need to be overly tight. Shin, among others, has suggested various modifications of this McCannel technique.

Sliding Knot Intracameral Suture

Siepser first described the closed-chamber, sliding knot technique in 1994. This technique heralded a paradigm shift in what surgeons can do within a contained anterior segment.

The sliding knot is created by first passing a fine suture through a limbal paracentesis incision. The needle then transcamerally engages both the proximal and distal iris tissue in the location of the desired stitch and is subsequently passed out of the limbus. The suture loop is then retrieved using a hook or intraocular forcep through the paracentesis, creating an externalized loop. The trailing strand of the suture is then passed through the externalized loop, once, twice, or three times ( Fig. 150.1 ). When the two suture ends are pulled, the suture is drawn into the eye with minimal tension on the iris tissue.

A knot can be achieved by making a second throw to secure the knot more tightly. There are two mechanisms by which the knot can be locked. The second throw is repeated identically to the first in a similar way, achieving a “granny” knot. If the end is passed up through the loop instead of downward, a square knot will ensue. A square knot can also be achieved by tying the second throw in a mirror image, or by inverting the orientation of how the suture loop is passed.

Once armed with the Siepser sliding knot, many patterns of rearranging the iris stroma can be achieved within an enclosed anterior chamber, primarily limited by the quantity and elasticity of the residual iris tissue. Narang and Agarwa describe a four-wrap, single throw variation of the Siepser siding knot, which can be especially helpful in very fragile iris tissue where retrieval of the suture for the second throw may risk tearing or stretching.

Iridodialysis Repair

There are numerous causes for an iridodialysis, namely prior trauma or intraocular surgery that disinserts the iris root. In addition, a pseudo-iridodialysis may occasionally be seen after reapproximation of a large sectoral iris defect. Repairing an iridodialysis or pseudo-iridodialysis requires a few special considerations. First, the goal is to close the defect between the disinserted iris and the internal scleral wall. Hopefully, this will reduce or eliminate both undesired glare from light scatter and possible shadow images from the pseudo-pupil created by such a defect. One needs to remember that the innervation and blood supply to the iris sphincter come in through the iris radially and, in the case of a larger iridodialysis, the sphincter muscle will be either focally denervated, ischemic, or both. This commonly leads to a partially, focally mydriatic pupil and usually requires imbricating sutures at the pupil margin in that sector as well. Furthermore, if long-standing, the band of disinserted iris can become somewhat curled up and fibrotic. Mechanically stretching this tissue gently between two radially positioned forceps can reduce this effect somewhat.

To reapproximate iris tissue, each end of a double-armed polypropylene suture is sequentially passed through a paracentesis site, engaged to the peripheral iris margin and passed out of the scleral wall at the level of the ciliary sulcus. If the surgeon makes the iris bites more peripheral to the edges of the dialysis than the scleral bites, this will effectively stretch the iris tissue toward the center of the defect, providing more iris tissue to fill the radial deficiency from the fibrotic band spanning the dialysis. The scleral bites should be at least 2 mm apart to permit rotation of the externally tied knot into the scleral wall. When the knot is thrown and the peripheral iris is reapposed, the pupil may be eccentric, requiring additional sutures and/or iris cautery. We prefer not to reappose the peripheral iris directly to the internal scleral wall, but, instead, to create just enough tension to cover the visible area of defect and let it hang back under the limbus slightly, both for ease of central pupil repair and also to prevent inadvertent blockage of the trabecular meshwork at that meridian. The knot can be completed with 3-1-1 throws and then trimmed with 1 mm tags. The knot and tags can be rotated into the scleral wall ( Fig. 150.2 ). Rather than rotating the knot internal to the scleral wall, some surgeons prefer to leave the suture knot under prepared partial-thickness scleral flaps or under patch graft material, both of which are suitable alternatives.

There are several other techniques and variations in the literature that aim to correct iridodialysis. Bardak et al. describe a threaded needle approach to transcameral iridodialysis repair in which a 26-gauge needle is passed through the sclera and iris into which a 10-0 Prolene (polypropylene) suture can then be docked and exited from the scleral wall. The process is similarly repeated for the other end of the Prolene suture, and the knot is tied externally under flaps. Khokher et al. describe a bimanual technique to repair an iridodialysis that aids in unfolding a curled-up iris. A bent 26-gauge needle acts as a platform by lifting and stabilizing the peripheral iris, resulting in support and counter traction for a 9-0 Prolene with a straight needle to gently stroke and unfold the iris tissue. The suture needle is then docked into the bevel of the 26-gauge needle and exited from the scleral wall. Silva et al. describe an elegant “sewing machine” technique using a single suture and single knot for a moderately sized iridodialysis. A loop of 9-0 Prolene suture is placed within a 27-gauge straight needle and subsequently passed through the peripheral iris and sclera. The suture loop is retrieved externally and held using an auxiliary anchoring suture. This maneuver is repeated every 1 hour of the iridodialysis, resulting in multiple loops of the same suture outside of the globe. The auxiliary anchoring suture is removed, and the continuous mattress suture is closed with a single knot.

Finally, an open repair though a larger limbal incision can be employed, although this carries the inherent risks of an open system, which may be particularly undesirable in a traumatized eye.