IFIS, capsule rupture and compromised support

Intraoperative Floppy Iris Syndrome (IFIS)

First characterized by David Chang and John Campbell in 2005, Intraoperative Floppy Iris Syndrome (IFIS) is an unpredictable, potentially sight-threatening intraoperative condition occurring in patients exposed to systemic $\alpha_1$-adrenergic receptor antagonists.

The Clinical Triad of IFIS

1. Flaccid Iris Stroma: The iris stroma billows, waves, and ripples in response to ordinary, gentle intraocular irrigation currents.
2. Propensity for Iris Prolapse: The loose iris tissue repeatedly herniates toward and prolapses out of the clear corneal and paracentesis incisions.
3. Progressive Intraoperative Miosis: The pupil constricts progressively throughout surgery despite aggressive, full preoperative pharmacological mydriasis.

Pharmacological Mechanism & The Tamsulosin Rule

• Receptor Selectivity: The iris dilator smooth muscle is innervated by sympathetic fibers acting on $\alpha_{1A}$-adrenergic receptors. Tamsulosin (Flomax) is a subtype-selective antagonist with high affinity for $\alpha_{1A}$ and $\alpha_{1D}$ receptors, widely prescribed for benign prostatic hyperplasia (BPH) and lower urinary tract symptoms.
• Other associations: Other alpha-1 antagonists, including silodosin (also relatively alpha-1A selective), and some psychoactive medicines can be associated with IFIS. Risk varies by drug and population; a universal greater-than-85% occurrence is inappropriate. Ask about past as well as current exposure.
• Structural Dilator Muscle Atrophy: Chronic receptor blockade causes permanent, structural disuse atrophy and tone loss in the iris dilator muscle.
• The Irreversibility Rule: Discontinuing tamsulosin prior to surgery does NOT prevent IFIS. Structural muscular atrophy persists for years after drug cessation. Patients who stopped tamsulosin years before cataract extraction remain at full risk for severe IFIS.

Intraoperative Management Protocol

1. Preoperative Preparation: Topical atropine $1\%$ drops twice daily for 2 to 3 days prior to surgery provides competitive muscarinic blockade, inducing maximal cycloplegia and stabilizing iris tone.

• Intracameral mydriatic preparations require a validated pharmacy formulation and local protocol.

1. Viscoadaptive OVDs: Highly viscous OVDs (e.g., Healon5) can be used to viscodilate and physically tamponade the iris.
2. Mechanical Pupil Expansion Devices:
   • Malyugin Ring: A square polypropylene expansion ring with four circular micro-scrolls that cradle the pupillary margin, maintaining an unyielding $6.25\text{ mm}$ or $7.0\text{ mm}$ round aperture.
   • Flexible Iris Retractors (Hooks): Four disposable retractors placed through dedicated stab paracenteses. Placing the sub-incisional hook directly beneath the main clear corneal incision in a "diamond" layout retracts the sub-incisional iris, completely eliminating iris prolapse into the phaco tunnel.
3. Low-Flow Fluidics: Decreasing aspiration flow rate ($20-25\text{ mL/min}$) and lowering bottle height minimizes intraocular turbulence.

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Posterior Capsule Rupture (PCR) & Vitreous Loss Management

Posterior capsule rupture occurs in approximately $1\text{ to }2\%$ of routine cataract procedures performed by experienced surgeons, but escalates to $5\text{ to }10\%$ in complex cases (pseudoexfoliation syndrome, posterior polar cataract, prior vitrectomy, traumatic zonular dialysis, dense brunescent cataracts).

Warning Signs of Posterior Capsule Rupture

1. Sudden, unexplained deepening or shallowing of the anterior chamber.
2. Sudden loss of fragment followability (debris refuses to approach the aspiration port).
3. Momentary pupillary snap or bounce.
4. Nuclear fragment tilting, sinking, or drifting away from the phaco tip.
5. Direct visualization of a torn capsular edge or a halo/bubble around the aspiration port.

The Golden Rule of PCR: DO NOT WITHDRAW THE PHACO TIP ABRUPTLY!

• Mechanism of Disaster: Withdrawing the phaco tip without active infusion causes immediate anterior chamber decompression and pressure collapse. Vitreous from the high-pressure vitreous cavity instantly surges forward through the capsular rent into the anterior chamber, transforming a small, manageable tear into a massive capsular disaster, shearing zonules, prolapsing vitreous through the corneal wounds, and dropping remaining nuclear fragments into the posterior segment.
• The Correct Emergency Protocol:
  1. Maintain Foot Position 1 (Irrigation Active): Keep the phaco tip steady in the eye with continuous irrigation running to maintain anterior chamber depth and counter vitreous upthrust.
  2. Inject Dispersive OVD Before Tip Withdrawal: Using the non-dominant hand, introduce a cannula through the paracentesis and inject a dispersive OVD (Viscoat) directly beneath the remaining lens fragments and over the capsular tear. The OVD tamponades the anterior vitreous face, pushes vitreous backward, stabilizes the fragments, and creates an artificial protective barrier.
  3. Withdraw Tip Under OVD Cushion: Only after the anterior chamber is completely filled with OVD and the vitreous face is sealed may the phaco tip be safely removed.

Principles of Anterior Vitrectomy

Once vitreous has prolapsed into the anterior chamber, the goal shifts to thorough, traction-free clearance of vitreous from the anterior segment and surgical wounds:

1. Separate infusion and cutting help control chamber stability and minimise traction; a limbal or pars plana approach requires appropriate training and anatomy.
2. Settings: Use a suitable high cut rate with controlled aspiration and infusion for the platform. Cutting before significant aspiration reduces traction; numerical settings and mode names are machine-specific.
3. Visualisation: An appropriate preservative-free triamcinolone preparation can reveal vitreous strands. Follow validated preparation and dilution instructions rather than treating one concentration as universal.
4. Completion: Inspect the pupil and wounds, chamber and remaining capsule. A round pupil alone does not prove that every vitreous strand has been cleared.

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Secondary IOL Selection & Fixation with Compromised Capsular Support

Assess the anterior capsular rim, zonules, vitreous clearance, iris and endothelium before implantation. With suitable anterior support, a sulcus-compatible three-piece lens may be used. Optic capture through an intact appropriately sized anterior capsulorhexis can improve centration and place the optic close to the bag plane.

Bag-designed single-piece acrylic lenses are unsuitable for the sulcus: thick haptics and optic edges can chafe the iris, causing pigment dispersion, recurrent bleeding, inflammation, pressure elevation and cystoid macular oedema (uveitis-glaucoma-hyphaema syndrome). Compatibility depends on the actual IOL design, not simply the number of pieces.

An optic wholly in the sulcus is more anterior and may require a power reduction; use an appropriate calculation for the lens power and position. Do not apply a universal 0.5 D reduction. With optic capture and a bag-plane optic, adjustment is often unnecessary.

If support is insufficient, options include an anterior-chamber lens in a suitable eye, iris fixation or scleral fixation. Evaluate angle and endothelial status, iris integrity and surgical risks. Anterior-chamber designs may require an iridectomy. Aphakia with delayed secondary implantation can be safer than forcing an unstable lens during complicated surgery.