Two suture bites on iris, 180° apart
Both suture loops from below the iris are externalized through the main tunnel
The right suture is looped twice around the leading haptic of a three-piece polymethyl methacrylate rigid intraocular lens with 6 mm optic, taking care that the suture loop lies over the haptic (Fig. 23.3). The leading haptic is then gently slid behind the iris, and the suture ends gently pulled such that the suture around the haptic becomes taut and does not slip from the haptic. The suture is looped and not tied to the haptic, as the position of the knot over the haptic may not be exactly symmetrical for both the haptics. Moreover, the position of iris bite may also vary, which means the IOL may be decentered or the pupil might peak after IOL placement. The other suture is similarly twirled twice around the trailing haptic, and the trailing haptic is placed in sulcus, dialing the lens very minimally so that the haptic is in line with the iris suture bite. Regular PMMA IOL is preferred instead of an IOL with eyelets, as the site of the iris bite may not be always predictable. In case the suture bite on the iris is either too anterior or posterior, passing the suture through an eyelet on a fixed location of the haptic may cause IOL decentration.
Both the suture loops are twirled around the leading and trailing haptics
Once the IOL is in position, both the suture ends of each bite are lifted gently to look for mild tilting of the lens as it is pulled. This is done to confirm that the suture that lies below the iris continues to support the haptic and that there is no slippage. The double loop over the haptic reduces the risk of suture slippage from the haptic while at the same time gives the liberty of varying the part of haptic, which is fixed to the iris.
To secure the knot, both suture parts in the anterior chamber are retracted out through the paracentesis using a Kuglen hook and McPherson forceps. The sutures are cut, and both the suture ends are tied together so that the suture knot lies over the iris. Around seven to eight knots are applied, so that the haptic is firmly secured to the posterior iris and the suture ends are trimmed. The other haptic is also secured to the iris in a similar fashion (Fig. 23.4). The suture ends are finally trimmed (Fig. 23.5). It helps if the paracentesis is around 1.2–1.4 mm long, so that the Kuglen hook can be comfortably passed through the side port and suture externalized. Care is taken to make sure that the suture knot is not too tight, as this may crumple the iris, causing distortion and pupillary peaking. One might even choose to pass the suture needle through a paracentesis rather than clear cornea while taking the iris bite and secure the knot using a modified Siepser slipknot.
Cross section of suture knot including the haptic and iris
Centered PCIOL sutured to the iris
The sclerocorneal tunnel is then closed with a single 10–0 nylon suture, and a thorough wash of the viscoelastic is done using controlled irrigation and aspiration with a Simcoe cannula. It is important to clear any vitreous, which may have prolapsed into the anterior chamber during the fixation maneuver. Stromal hydration of the paracentesis sites is then done to ensure a well-formed anterior chamber. After making sure there is no wound leak, the conjunctiva is reposited, and cauterization of the conjunctival flap is done using a bipolar electrical cautery.
If done as a primary procedure in eyes with intraoperative complications such as large zonular dialysis or posterior capsular rupture, the same technique is followed after thorough anterior vitrectomy.