BLOG: How to avoid the heartbreak (and potential lawsuits) of a flaccid iris
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Few issues are as prone to causing complications during cataract surgery as an iris that will not stay dilated.
Cataract surgeons must open the capsule, break and emulsify the lens, remove all fragments, and insert a new IOL through the aperture of the pupil — difficult enough when the pupil is dilated to 8 mm, but hellish when the pupil shrinks to 5 mm or less. Unwanted intraoperative miosis is such a common cause of complications that Expert Institute, a website for litigators, has a whole section devoted to the topic.
Difficult irides had bedeviled surgeons for years, but the case was not cracked until 2005, when an astute team of surgeons investigated. They named the condition intraoperative floppy iris syndrome (IFIS) and defined it as a triad of issues during cataract surgery — a flaccid iris stroma that undulates and billows during surgery, a tendency of the iris to prolapse through corneal or limbal incisions and a progressive intraoperative miosis.
Their great breakthrough was the identification of a commonality in almost all cases: the usage of Flomax (tamsulosin, Sanofi), a common medication used for an enlarged prostate.
Tamsulosin’s effect on the iris
Men’s prostates typically enlarge throughout life. As the prostate grows, it presses on the urethra and impedes urination, a condition known as benign prostatic hyperplasia (BPH); by age 80, roughly 90% of men are affected, according to Penn Medicine.
Normally the flow of urine is controlled via the constriction of smooth muscle in sphincters surrounding the ureter. These muscles are primarily triggered via specialized neuroreceptors called alpha-1 adrenergic receptors. Tamsulosin is often used to relieve the pressure on the urethra, as it is an effective drug at selectively and competitively blocking alpha-1 adrenergic receptors; it is a “selective alpha-1 adrenergic antagonist,” or alpha-1 adrenergic blocker.
Unfortunately, there is one more smooth muscle where this receptor subtype dominates: the radial muscles that dilate the iris. The iris dilates in response to stimulation by the sympathetic system, mediated by alpha-1 adrenergic receptors, whereas constriction is regulated by the parasympathetic system. Therefore, in the iris, tamsulosin has the opposite effect as it does in the urethra; the constriction sphincter of the iris is unopposed by the dilators and the pupil tends to lose tautness and shrink.
The complications associated with IFIS come from the iris’s lack of tone and loss of mydriasis. When the iris loses its tone during surgery, it can prolapse into an incision, leading to iris damage and pupil deformity, or even endophthalmitis. When the iris loses its mydriasis, the surgeon’s job becomes more difficult, and the risks rise for posterior capsular tears, vitreous prolapse and lens fragments in the anterior or even posterior segments. Additionally, any complex surgery increases the risk for cystoid macular edema, ocular hypertension or later retinal detachments.
Other risks, considerations
Tamsulosin is currently the most commonly prescribed medication for BPH. It also has the greatest affinity for the alpha-1 adrenergic receptor subtype, but other medications can cause IFIS to a lesser extent. Cataract surgery centers will be wary with any patient on the other alpha-1 antagonists, including medications ending in -osin — doxazosin, prazosin, terazosin, alfuzosin, silodosin — but also finasteride and even saw palmetto.
Tamsulosin is overwhelmingly prescribed for men, but urologists do occasionally prescribe it for women to help with urinary retention. Because this is not expected and often overlooked in women, they can have higher IFIS-related complication rates than men.
Although discontinuing tamsulosin can be helpful, it does not fully eliminate the risk for IFIS. Patients have been observed with IFIS years after discontinuation, possibly due to a disuse atrophy of the dilator smooth muscle. In addition, patients have been noted to have IFIS after only one single instance of tamsulosin usage. Since the major risk with IFIS is of being unprepared, most clinics do not ask patients to discontinue their tamsulosin, but the surgeon is prepared for a more challenging surgery. With IFIS, anticipation is crucial to lowering the risk.
A surgeon who is expecting IFIS can use a variety of techniques to reduce the risk for complications, including atropine for dilation, mechanical pupil expansion devices, viscoelastic agents, intracameral epinephrine and careful control of intraocular fluid dynamics.
Tamsulosin-driven IFIS has led to intraoperative complications, disappointing surgical outcomes and even lawsuits. As a primary care optometrist, the most important steps you can take to avoid a bad outcome are twofold: First, carefully counsel your patient on the increased risk that they will undergo when they get cataract surgery; a foreseen complication makes you look competent. Second, highlight the medication usage to the surgery center; this allows them to plan for a more challenging surgery, and your communication demonstrates your recognition of the risk.
References:
- Chang DF, et al. J Cataract Refract Surg. 2005;doi:10.1016/j.jcrs.2005.02.027.
- Enlarged Prostate. https://www.pennmedicine.org/for-patients-and-visitors/patient-information/conditions-treated-a-to-z/enlarged-prostate. Accessed Dec. 21, 2023.
- Floppy iris syndrome causes and treatment strategies. https://www.expertinstitute.com/resources/litigation-guides/floppy-iris-syndrome/. Accessed Dec. 12, 2023.
For more information:
Oliver Kuhn-Wilken, OD, practices at Pacific Cataract and Laser Institute’s Tualatin Clinic in Oregon.
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