Brandon D. Ayres, MD
For as long as there has been cataract surgery, there have been complications of cataract surgery. As early as 1976, Dr. Malcolm McCannel described a retrievable suture technique that could be used to fixate a dislocating posterior chamber intraocular lens (PCIOL). The technique was first described for repair and fixation of dislocated implants but was later refined and used for fixation of PCIOLs in the absence of capsular support.1
This technique is easy to conceptualize and well within the skill set of an anterior segment surgeon. The iris fixation technique involves using a 10-0 polypropylene suture to capture both haptics of a 3-piece IOL to the posterior surface of the iris to fixate the implant in position. While the sutures are being passed, the optic of the IOL is captured anterior to the iris plane. Once the sutures are tied, fixating the haptics, the optic is reposited into the posterior chamber. Although this technique may sound straightforward, complications can arise in the operating room as well as postoperatively.
In many cases, iris fixation can be planned to help reposition a dislocating 3-piece IOL. One usually avoidable complication is progressive subluxation of the implant to the point that it is difficult or even impossible to recover from the anterior segment approach. Careful exam with attention to IOL position with the patient sitting at the slit lamp and also supine in the exam chair can help identify an IOL that is at high risk for complete dislocation into the posterior segment. If the IOL migrates posteriorly on exam, plans can be made to have a retinal surgeon present to help elevate the IOL for suture fixation or exchange. Even with the best planning, cases will occasionally arise where the lens looks amenable to fixation from the anterior approach but complete dislocation is found in the operating room.
Another intraoperative challenge is capture of the optic anterior to the iris (iris capture). In many cases, the implant is already unstable, and trying to elevate the optic into the anterior chamber may be difficult or cause further instability of the IOL. Rotating the optic anteriorly with an IOL manipulating hook (such as a Sinskey hook) is basically impossible. Use of microforceps to grab onto the edge of the optic and lift the optic up and above the iris plane can be much more effective and less likely to cause posterior dislocation of the implant. Another helpful technique to elevate and support a dislocating implant is to use a pars plana incision and microforceps for posterior elevation. If using a pars plana approach, it is essential that an adequate vitrectomy is performed to prevent vitreous prolapse, incarceration, and traction on the retina.
Once the IOL is elevated, it must be held in place while a miotic agent is used to constrict the pupil. Constriction of the pupil will help temporarily hold the implant in place while the suture is passed. The more miotic the pupil, the easier it is to keep the optic captured and visualize the haptics. Keeping in mind that miosis will eventually be necessary, care must be taken when deciding which medications should be used for pupil dilation. Use of phenylephrine and tropicamide only (not cyclopentolate) may be advantageous when trying to constrict the pupil later in the case. Similarly, intraoperative dilating agents such as epinephrine or phenylephrine should be avoided, because they will prevent the intraoperative miotic agents from fully constricting the pupil. Keeping the optic well fixated in the iris not only prevents posterior dislocation during the surgical procedure but provides rotational stability to the lens. A more stable lens will allow proper centration of the optic once the sutures are placed and the optic is prolapsed into the posterior chamber.
Difficulty in passing the polypropylene suture is another commonly encountered problem. The use of a 10-0 polypropylene suture on a long curved vascular needle is recommended. The needle will need to be passed through a limbal paracentesis, then through the iris, under the haptic, out through the iris, and then exit the eye through a limbal wound. An exit paracentesis is not necessary, as the needle can be used to make the exit wound. The suture pass should be as peripheral as possible and incorporate as little iris as possible. Directing the paracentesis toward the limbus will help prevent “oar-locking” of the needle, making it significantly easier to make the suture pass. When first passing the needle through the paracentesis, make sure to gently wiggle the needle. Movement of the needle will help ensure the needle is free from the corneal stroma. Incorporation of corneal fibers will lead to significant distortion of the pupil, decentration, and tilt of the IOL (Figure 29-1).
Once the needle of the 10-0 polypropylene is in the anterior chamber, the suture must be passed through the iris and under the haptic of the IOL. Visualization of the haptic can be difficult. Improper suture fixation of the haptic will lead to dislocation and decentration of the implant. To simplify visualization of the haptics beneath the iris, the optic of the lens can be elevated with an IOL positioning hook or microforceps (Figure 29-2).
A technique using the second needle of the double-armed polypropylene suture has also been described to assist with elevation of the optic. With this technique, the unused needle is passed into the anterior chamber, under the optic of the IOL, and out through the limbus. The needle will then elevate the optic, helping to visualize the haptics and allowing the surgeon to use both hands to assist with the suture pass. An excellent technique using a curved needle to help with visualization was described by Dr. John Hart.2 As with any suture pass, intraocular hemorrhage may be seen. The less traumatic the suture pass, the less the risk of significant hemorrhage in the anterior chamber.
One of the most common complications of iris-sutured lenses is ovalization of the pupil3 (Figure 29-3). In many cases, this is not visually significant but may be cosmetically significant, especially in patients with light-colored iridies. Two common causes of ovalization are excessive incorporation of the iris stroma into the suture bites and overtightening of the knots. Keeping the bites of iris stroma as small as possible will help prevent the bunching of the fibers that leads to ovalization. Maximizing visualization of the haptic beneath the iris will aid in suture placement along with making sure to incorporate a small amount of iris stroma. I will often pass microforceps under the optic of the IOL to elevate the lens, making it easier to see the haptics under the iris.