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Capsular Support Devices - Complete Notes

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1. INTRODUCTION

• Zonular weakness increases risk of intra- and postoperative complications during cataract surgery:
  • Posterior capsular rupture
  • Vitreous loss
  • Lens dislocation and decentration
• Capsular support devices improve capsular bag stability and centration
• Four main types:
  1. Standard Capsular Tension Rings (CTR)
  2. Modified Capsular Tension Rings (Cionni rings)
  3. Capsular Tension Segments (CTS)
  4. Capsular Retention Hooks

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2. EVALUATION

Risk Factors for Zonular Weakness

Preoperative Signs of Weak Zonules

• Iridodonesis (iris trembling)
• Phacodonesis (lens trembling)
• Abnormal anterior chamber depth or asymmetry
• Angle asymmetry on gonioscopy
• Vitreous in the anterior chamber
• Zonular dehiscence / lens subluxation or dislocation (in advanced cases)

Intraoperative Signs of Weak Zonules

• Anterior chamber depth fluctuation
• Difficulty puncturing the anterior lens capsule
• Star-shaped striae on the capsule surface during capsulotomy
• Lens movement during capsulorrhexis
• Difficulty rotating the nucleus despite adequate hydrodissection

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3. TYPES OF CAPSULAR SUPPORT DEVICES

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3A. Standard Capsular Tension Ring (CTR)

Structure

• Flexible C-shaped device made of PMMA (polymethylmethacrylate)
• Blunt-tipped eyelets at each end (aid insertion)
• When placed in capsular bag: exerts outward centrifugal force - redistributes tension from intact to weak/absent zonular zones

Indications

• Mild diffuse zonular weakness
• Focal zonular weakness spanning < 3-4 clock hours

Contraindications (Absolute)

• Anterior or posterior capsular tears
• Any concern for bag compromise
  • Reason: centrifugal forces from the ring can propagate a capsular tear

When CTR is NOT Adequate

• Advanced zonular weakness
• > 4 clock hours of zonular loss
• Progressive zonulopathy
  • These eyes need scleral-fixatable endocapsular devices (modified CTR or CTS)

Available Devices (FDA Approved - 2 rings)

• Morcher ring is slightly stiffer than the Ophtec ring

Sizing

• Correctly sized ring: ends slightly overlap, diameter slightly larger than capsular bag
• Estimation based on: horizontal white-to-white measurement + globe axial length
• Implanting the largest available ring is not unreasonable - no apparent disadvantage

Capsulorrhexis Size

• Preferred: 5.0-5.5 mm diameter
• Too small → makes phacoemulsification harder + risk of capsular phimosis
• Too large → may preclude use of endocapsular support devices

Ring Insertion Technique

• Can be inserted any time after capsulorrhexis
• Guiding principle: "Insert as early as required but as late as possible"
  • Early insertion = early stabilization but may trap cortex between ring and capsular wall
• Methods:
  1. Injector (single-use preloaded - available for Morcher & Ophtec rings)
  2. Manual dialing using forceps + Sinskey hook
  3. "Fish tail" technique (newer) - no dialing or injection required; may limit zonular stress
• Important: Leading arm should be directed toward the area of weak zonules
• Note: Ophtec ring is NOT compatible with the Geuder (Heidelberg) reusable injector

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3B. Modified Capsular Tension Ring (Cionni Ring)

• Developed to address limitations of standard CTR in profound zonular weakness
• Also a C-shaped PMMA device, but has one or two additional eyelets located 0.25 mm anterior to the plane of the ring
• Can be permanently sutured to the sclera via these eyelets
  • Suture material: 9-0 polypropylene or CV-8 GoreTex
• Must be dialed in manually - cannot be injected

Indications

• Advanced zonular weakness
• > 4 clock hours of weak zonules
• Progressive zonulopathy

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3C. Capsular Tension Segment (CTS)

• Partial PMMA segment providing 90° of capsular support
• Has a central eyelet extending anterior to the ring plane for scleral suture fixation
• Indicated for advanced zonular weakness

Advantages over Cionni Ring

• Does not require dialing
• Can be used in the presence of anterior or posterior capsular tears (unlike CTR)
• Can be used for both intraoperative stabilization AND postoperative fixation
• Less likely to trap cortical material against the capsular wall
• One or more CTS can be used in the same eye
• Can be paired with a standard CTR to provide circumferential support

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3D. Capsular Retention Hooks

• Provide intraoperative capsular bag stabilization only (temporary)
• Indicated for advanced zonular weakness

Available Systems

1. Mackool Capsular Support System (FCI Ophthalmics)
   • Modified nylon iris hooks
   • Support the anterior capsule edge
   • Secured by a retainer tab during surgery
   • Advantage: Allows cortex removal before CTR insertion
2. MicroSurgical Technologies retractors (Redmond, WA)
   • Loop of double-banded nylon
   • More capsule-equator-friendly than Mackool hook
   • Chang modification prevents CTR from becoming trapped in the loop (a limitation of 1st-generation retractors)

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4. OUTCOMES

Benefits of CTR

• ↓ Intraoperative: zonular dehiscence, posterior capsular rupture, vitreous loss
• ↓ Postoperative: lens decentration, lens tilt, posterior capsular opacification (PCO)
• No effect on refractive outcome - IOL power calculation modification is NOT necessary

Complications / Risks

Prevention of Late Subluxation

• Use a sutured modified CTR or CTS
• Weigh against risks of increased intraocular manipulation and suture complications

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5. QUICK COMPARISON TABLE

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6. KEY CLINICAL PEARLS

• Always identify zonular weakness before surgery when possible
• Pseudoexfoliation syndrome is one of the most common and important risk factors - associated with late dislocation
• The choice of device depends on extent (clock hours), severity, and progression of zonulopathy
• A CTS can be combined with a standard CTR for maximum circumferential support
• The "fish tail" technique for CTR insertion may reduce zonular stress
• Late bag-IOL-CTR complex dislocation in progressive zonulopathy may require vitreoretinal surgical approach for removal