There are numerous reasons why an intraocular lens (IOL)can drop into the posterior chamber during or after cataract surgery. Weak zonules or a history of trauma are two likely causes, but we see this complication in completely unanticipated cases as well. Unfortunately, the fix is rarely simple. These four steps can help you identify the complication and guide patients through the process.
Step One: Find the Problem
Symptoms of a dislocated IOL include a sudden decrease in vision, distorted vision or flashes of light. You will likely also notice a large hyperopic prescription during autorefraction.
Any sudden change in vision should prompt dilation because the anterior chamber can often look normal with the lens behind the iris. Unless the patient is dilated, the dislodged lens is easy to miss. It will most likely settle on the inferior retina, but a careful 360-degree funduscopic examination is necessary to rule out a posteriorly dislocated IOL. Patients often look fine superficially and have minimal intraocular inflammation.
Note: If this is the first time you are seeing a patient, the absence of an IOL does not always mean something is wrong; there are several situations during which the surgeon may elect to leave a patient aphakic.
Step Two: Alert the Team
Upon discovering a posteriorly dislocated IOL, you must immediately inform the surgeon and a local retina specialist. However, this does not necessary constitute a true emergency. IOLs are sterile, and surgical intervention—which is complex and usually requires a fair bit of planning—can often be delayed several days without any detrimental effect.
Step Three: Surgery
The cataract and retina surgeons can choose several different methods of retrieving the IOL and either replacing or securing it. It can be a one-step procedure or split into two: IOL removal and then implantation and securing. In addition, the surgeons may decide to do the combined procedure together, or the retina surgeon may be able to do it alone. To remove the IOL, it must first be cut up in the posterior chamber and then taken out through the small scleral ports.
After an IOL has been dislocated, no adequate capsular bag exists to hold a lens. The two most common options to secure the IOL into position is suturing it to the iris or the sclera. Suturing to the iris can damage the iris and limit the patient’s ability to have a dilated exam in the future. Securing the lens to the sclera usually carries fewer long-term complications, but is a much trickier surgical option.
Step Four: Follow up
Postoperative management after IOL reposition and fixation is not significantly different from routine cataract surgery. The medications are the same, and the patient should have a relatively quiet eye. However, you need to keep an eye on the retina for any residual inflammation or possible subclinical tears.
Previously an invasive and traumatic procedure, IOL reposition and fixation has been refined with newer technologies and techniques so that today’s patients are quite functional the next day—and optometrists are now an integral part of the pre- and postoperative care team.
The authors would like to thank Alan Franklin, MD, PhD, for contributing this month’s video.