Floppy Iris Syndrome

Floppy Iris Syndrome

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Chief Complaint:

Decreased vision in the left eye.

History of Present Illness:

The patient is an 83-year old male who presented to the clinic for gradual worsening of vision in the left eye. He had cataract surgery in the right eye two years ago with an excellent outcome. Since then he has had increased difficulty reading with the left eye.

Past Ocular History:

• Pseudophakia right eye (OD) s/p uncomplicated phaco/IOL 2 years ago
• Cataract left eye (OS)
• Presbyopia

Medical History:

• Heart disease - pericardial effusion, coronary artery disease, atrial fibrillation
• Central sleep apnea
• Tremor
• Benign prostatic hyperplasia

Medications:

• Ascorbic acid 500 mg daily
• Aspirin 325 mg daily
• Carboxymethylcellulose 1 drop OS 5 times per day
• Docusate 100 mg daily
• Finasteride 1 mg po daily
• Levothyroxine 0.05 mg daily
• Metoprolol tartrate 25 mg bid
• Psyllium prn
• Tamsulosin 0.4mg daily
• Topiramate 25mg bid

Allergies: No known drug allergies

Family History: No significant family history

Social History:

• Former smoker - 1 pack per day; quit 15 years ago
• Alcohol - 1-2 drinks per week

Review of Systems: A complete review of systems was negative

Ocular Examination	OD	OS
Visual acuity with correction	20/20-1	20/100
Pinhole	No improvement	No improvement
MRx	Plano	-2.50 sphere, 20/100
Motility	Full	Full
Intraocular pressure	9 mmHg	9 mmHg
Pupils	4 mm light, 2 mm dark, brisk, no RAPD	4 mm light, 2 mm dark, brisk, no RAPD
Confrontation visual fields	Full	Full

Slit Lamp Exam	OD	OS
Lids and lashes	Normal	Normal
Conjunctiva and sclera	Normal	Normal
Cornea	Clear	Clear
Iris	Poor dilation (5 mm)	Poor dilation (5 mm)
Anterior chamber	Deep, no cell	Deep, no cell
Lens	Posterior chamber intraocular lens centered and clear	Central posterior subcapsular cataract, 3+ nuclear sclerosis, 1+ cortical changes
Anterior vitreous	Normal	Normal

Dilated Fundus Examination: Within normal limits OU

Diagnosis

Visually significant cataract in the left eye. Surgical planning will have to account for the small pupil and prior tamsulosin use.

DISCUSSION

Pathophysiology of pupillary constriction and dilation:

Dilation of the pupil involves two integrated processes, the relaxation of the iris sphincter and the contraction of the iris dilator. Iris sphincter relaxation occurs when there is supranuclear inhibition of the Edinger-Westphal nucleus at the central nervous system level, predominantly by the reticular activating system in the brainstem. When this inhibition occurs, there is a decrease in the parasympathetic stimulation of the iris sphincter resulting in relaxation of the muscle and subsequent pupillary dilation. This inhibition is inactivated during periods of sleep or under the influence of anesthesia or narcotics resulting in pupillary constriction [1].

Increased output to the peripheral sympathetic nervous system also causes pupil dilation by stimulating the iris dilator muscle, but this peripheral sympathetic innervation is not required for pupil dilation. Humoral mechanisms such as catecholamines may also act on the iris dilator muscles, either through the blood or through the tears, to cause pupil dilation [1].

There are multiple etiologies for poor pupillary dilation and several mechanisms could be applicable in the patient described in the case above. Advanced age may result in decreased inhibition at the midbrain from the reticular activating system which results in poor pupil dilation. Cholinergic agonists (enhancing the parasympathetic pupillary response of constriction) or sympathetic antagonists such as tamsulosin, an alpha-1a receptor blocker, also hinder dilation.

Differential diagnosis for small pupils [2]:

Opioids, sympatholytic medications such as benzodiazepines or clonidine, Horner's syndrome, miotic medications, neurosyphilis (Argyll Robertson pupils), pontine infarction, uveitis, inflammatory adhesions between the iris and the lens (posterior synechiae), cholinergics, physiologic anisocoria, advanced age, alpha-1 receptor antagonist use.

Other etiologies such as pseudoexfoliation syndrome and trauma from prior injury or surgery do not necessarily cause small pupils, but may result in poor pupillary dilation.

Floppy iris syndrome secondary to tamsulosin use

Intraoperative Floppy Iris Syndrome (IFIS) is defined by three intraoperative clinical features [3].

• A flaccid iris stroma that flutters and billows in response to physiologic intraocular fluid currents (See video below or, if it fails to load, use the alternative direct link to video on YouTube),
• A tendency for the iris stroma to prolapse toward the phaco and side-port incisions despite proper wound construction, and
• Progressive pupil constriction despite standard preoperative pharmacologic measures to prevent this.

Video, approx 2:42

IFIS may be graded according to the severity of symptoms present during cataract surgery. Mild IFIS is characterized by iris billowing without intraoperative miosis or prolapse. Moderate IFIS results in iris billowing and miosis without iris prolapse. In severe IFIS, there is iris billowing and miosis with a tendency of the iris to prolapse out of the surgical incisions [4].

α1-adrenergic receptor antagonists, most notably tamsulosin, are notorious for causing IFIS [5]. This trend was first described in 2005 by Chang and Campbell [7]. The reported incidence of IFIS associated with tamsulosin ranges from 43% to 100% [4, 6]. In addition to blockingα1-adrenergic receptors in the prostate, it is thought that tamsulosin also blocksα1-adrenergic receptors supplying the iris dilator muscle. Its long half-life and constant receptor blockade may result in diffuse atrophy of the iris dilator smooth muscle [7].

α1-adrenergic receptor antagonists have been shown to have multiple effects on the iris and its dilation. Men on both tamsulosin and afluzosin were found to have smaller pre-dilation maximum pupil diameters and slower constriction velocities compared to men not takingα1-adrenergic receptor antagonists. There was also a smaller percentage change from maximum pupil diameter to minimum pupil diameter. Following dilation, men on tamsulosin were found to have a smaller maximum and minimum pupil diameter as compared to men not takingα1-adrenergic receptor antagonists [3]. The effects of adrenergic antagonists on iris behavior are not correlated with the dose or duration of therapy, and discontinuing the medication seems to have no effect on the degree of IFIS [8].

IFIS has been associated with a variety of other drugs including saw palmetto, finasteride, antipsychotic drugs, angiotensin antagonists, and some b-blockers with particular a-blocking properties [3, 8]. IFIS is typically less common and less severe in these medications compared to tamsulosin [9, 6].

Surgical Concerns of IFIS:

IFIS presents problems during cataract surgeries by decreasing the size of the work field and increasing the rate of complications such as iris trauma, posterior capsule rupture, and vitreous loss. In order to prevent these complications, it is important to recognize the risk of IFIS prior to cataract surgery and prepare a pre-operative plan [5].

Pharmacologically induced mydriasis has been shown to have a decreased response in patients taking anα1-adrenergic receptor antagonists prior to surgery both with standard mydriasis induction and heavier pre-operative mydriatics plus topical lidocaine. Additionally, patients takingα1-adrenergic receptor antagonists have smaller pupil diameters at the conclusion of cataract surgery compared to those who were not takingα1-adrenergic receptor antagonists [5].

A dilated pupil diameter of 7.0 mm or less was shown to identify patients at risk for moderate to severe IFIS with a sensitivity of 73% and a specificity of 95%, and therefore the size of the pupil must be taken into preoperative planning [4].

Techniques to control IFIS:

While there is no known mechanism to reverse the pupillary effect ofα1-adrenergic receptor antagonists, several pharmacologic and mechanical techniques to improve pupillary dilation have been implemented.

Pharmacologic techniques are aimed at overcoming the adrenergic blockade of the iris dilator muscles caused by tamsulosin. Shugar demonstrated that an intracameral epinephrine injection may be useful in maintaining pupil dilation in patients taking tamsulosin during cataract surgery [10]. The mixture was slowly injected into the anterior chamber prior to instillation of the viscosurgical device and again between phacoemulsification and irrigation/aspiration to maintain dilation. By similar mechanisms, intracameral phenylephrine hydrochloride injected into the anterior chamber prior to injection of the viscoelastic aids in pupillary dilation [11]. Presurgical topical atropine sulfate 1% with intraoperative 1:2500 epinephrine hydrochloride has also been found to be useful in managing IFIS during cataract surgery [10].

Specific surgical techniques have also been useful in controlling IFIS. The separation of irrigation and aspiration in a bimanual approach has been described as a way to reduce the degree of iris movement [11]. This is thought to allow for safe removal of the cortical lens by not creating a 1-way valve at the main incision.

The use of ophthalmic viscosurgical devices (OVDs) such as high concentration sodium hyaluronate (Healon5, Abbott Laboratories Inc.) may aid in preventing IFIS. OVDs aid in viscodilation of a small pupil. In addition, the highly cohesive properties also allow it to act as a barrier against a prolapsing iris. When using OVDs, low aspiration and vacuum settings should be used to prolong the OVD presence within the eye. It is also important not to overfill the eye with OVD, as it may promote fluid expulsion from the eye, increasing the risk of iris prolapse through the corneal incision [12].

More definitive mechanical devices such as iris hooks or Malyugin rings are very useful when operating on small pupils, especially in the setting of prior tamsulosin use. Iris hooks ensure a relatively stable surgical field. Initially, four iris retractors were inserted to create a square-shaped pupil from the surgeon's perspective. However, it has been noted that this allows for tenting of the iris near the insertion site of the phacoemulsification needle, which could allow for prolapse of the floppy iris through the corneal incision. Oetting and Omphrey described placing the retractors in a diamond configuration, from the surgeon's perspective, to pull the iris under the wound and prevent iris prolapse[13]. This allows the phacoemulsification needle to pass over one of the retractors and prevents iris prolapse into the corneal wound.

Malyugin rings which come in 6.25 and 7.0 mm sizes, and other pupil expansion devices, may be used during cataract surgery to ensure mydriasis and a stable surgical field. Unfortunately, the Malyugin ring is not able to engage iris margins when pupil diameters exceed 7.0mm. Nonetheless, this device is very useful in maintaining an adequate surgical field in small pupils. Peripheral iris prolapse into the incisions is still a possibility when using the rings [4].

Patient Outcome:

Given the patient's history of tamsulosin use and 5.0 mm dilated pupil diameter at the start of surgery, a 6.25 mm Malyugin ring was used during the cataract surgery. Some billowing of the iris was noted during surgery, but no complications occurred during the procedure. At the end of surgery, the pupil was 3 mm in diameter after removal of the Malyugin ring. This highlights the importance of the Malyugin ring or iris hooks to dilate and stabilize the iris in patients with a small pupil and prior tamsulosin use.