December 2013




Tools & techniques

Managing iris prolapse when sealing the wound during cataract surgery

by Daniel H. Chang, MD


Richard Hoffman, MD

Howard Fine, MD, has taught me to treat every small pupil case as an IFIS case. When I first heard his tenet, I was of course skeptical—I am by nature a doubter. With experience, observation, and many frustrating intraoperative moments, I have come to appreciate his wisdom in regard to the small pupil. I have seen numerous cataract cases with what appears to be adequate 5-6 mm pupils turn into nasty whirlwinds of distress and iris transillumination in patients who for the most part have no pharmacologic risk factors for IFIS. Using a biaxial technique and a pupil expansion device in these borderline dilators has for the most part eliminated the development of floppy irises until after viscoelastic removal, following removal of the pupil ring or hooks.

In this month's column, Daniel H. Chang, MD, provides a succinct overview of the fluidics of iris prolapse. He gives several useful tips for both preventing iris prolapse and repositioning the prolapsed iris with minimal tissue trauma. It's a quick read and very useful for maximizing outcomes in the floppy iris patient.

Richard Hoffman, MD, Tools & techniques editor

Iris prolapse

Figure 1: Iris prolapse

I/A tip in eye Figure 2: Stop irrigation and soften the eye prior to withdrawal of I/A tip. Note the corneal striae in a soft eye.

Paracentesis port Figure 3: Tap the paracentesis port.

Anterior lip of the wound Figure 4: Press on the anterior lip of the wound.

Tangentially hydrate the stroma Figure 5: Tangentially hydrate the stroma.

Source (all): Daniel H. Chang, MD

Few things are more frustrating during cataract surgery than iris prolapsing into the wound. Various surgical devices—including iris hooks, iris rings, and viscoelastics—can help to manage the iris during the procedure. However, none of these devices can be utilized at the end of the case, when the wound is being sealed with stromal hydration. Intended to seal the wound, stromal hydration can create a high-flow state that actually elicits iris prolapse (Figure 1).

To develop a strategy for managing iris prolapse, it is important to understand the fluidics that cause this complication. Because of Bernoulli's principle, rapid fluid egress from a wound creates a negative pressure gradient that draws iris into the wound and out of the eye. Iris goes where fluid flows, so managing the fluidics can manage the iris. By reducing the pressure gradient across the wound, fluid flow is reduced, and cases of prolapsing iris can be remedied without poking, sweeping, or otherwise touching the iris. This can be achieved through four simple techniques.

1. In cases at risk for iris prolapse (e.g., in an eye with intraoperative floppy iris syndrome), if the I/A tip is withdrawn rapidly, the elevated IOP from the irrigation will result in a large pressure gradient with rapid fluid (and iris) egress. To prevent this, simply stop the irrigation and allow the eye to soften slightly prior to removing the I/A tip (Figure 2).

2. If iris does prolapse despite softening the eye prior to I/A tip removal, the urge to push it back with a cannula should be resisted. Instead, the pressure gradient across the wound can still be lowered by tapping the paracentesis port (Figure 3). Continued lowering of the IOP stops the fluid flow through the wound, frequently retracting the iris back into the eye.

3. If the iris does not settle back in the eye with fluidics alone, gentle pressure can be used to reposition the iris by massaging the anterior lip of the wound with the cannula (Figure 4). This squeezes the iris back into the eye without touching the iris. After the iris is out of the wound, pressing the anterior lip of the wound helps to facilitate wound closure and sealing.

4. The stroma is hydrated without filling the eye and raising the IOP. By directing the irrigation cannula as tangentially to the incision as possible and by slowly injecting (Figure 5), the wound can be sealed with minimal fluid egress and no iris prolapse. Stromal edema should appear without deepening the anterior chamber. When the wound seals, it is then safe to fill the eye. The anterior chamber will deepen and the iris will move posteriorly, away from the wound.

Using a combination of these four maneuvers, a case of iris prolapse can be resolved quickly and easily. It is important to remember that when lowering the IOP to subphysiologic levels (note corneal striae in Figures 2 and 3), there is a theoretical risk of suprachoroidal hemorrhaging. Therefore, it is important to address modifiable risk factors such as systemic arterial hypertension, coughing, and the duration of hypotony. In reality, these steps can be performed in a matter of seconds, helping to complete a case with negligible risk.

With these simple techniques, iris prolapse can be managed with confidence instead of frustration. By managing fluidics and avoiding direct iris manipulation, trauma is minimized, and a once-frustrating complication can be resolved with a simple solution.

Editors' note: Dr. Chang is a partner at Empire Eye and Laser Center in Bakersfield, Calif. He has no financial interests related to this article.

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