What are the indications for using a Capsular Tension Ring (CTR) versus a Capsular Tension Segment (CTS) in patients with zonular weakness or dehiscence during cataract surgery, based on the extent of zonular dialysis?

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Management of Zonular Weakness/Dehiscence During Cataract Surgery

Device Selection Based on Extent of Zonular Dialysis

For zonular dialysis less than 3-4 clock hours (approximately <120°), use a standard Capsular Tension Ring (CTR); for dialysis greater than 3-4 clock hours (>120°), use a Capsular Tension Segment (CTS) with scleral fixation. 1, 2

CTR Indications (Mild to Moderate Zonular Weakness)

  • Use standard CTR for zonular dialysis <120° (approximately 3-4 clock hours) where the remaining zonular support is sufficient to maintain capsular bag stability 1, 3
  • CTR insertion significantly improves both early and medium-term visual outcomes in patients with zonular dialysis, with better best-corrected visual acuity compared to cases without CTR use 3
  • The CTR redistributes capsular tension circumferentially, stabilizing the capsular bag and preventing progressive decentration during and after surgery 2, 4

CTS Indications (Severe Zonular Weakness)

  • Deploy CTS for zonular dialysis >120° (approximately 4 clock hours or greater) where zonular support is insufficient for standard CTR alone 1, 2
  • CTS provides direct scleral fixation in the area of maximal zonular weakness, offering mechanical support that a standard CTR cannot provide 1, 2
  • The sutureless double-flanged technique with CTS allows for effective management of extensive zonular dialysis without traditional suturing complications 1

Surgical Technique Considerations

Preoperative Assessment

  • Femtosecond laser-assisted cataract surgery (FLACS) with integrated AS-OCT can detect zonular dehiscence that may not be visible on standard preoperative imaging, allowing for better surgical planning 5
  • FLACS creates consistent capsulorhexis and performs lens fragmentation with minimal zonular stress, which is particularly advantageous in zonulopathy cases 5

Intraoperative Decision Algorithm

For dialysis extending 180-200°:

  • Avoid CTR placement entirely as it may cause further iatrogenic zonular damage 5
  • Consider sulcus IOL placement with optic capture through an intact capsulorhexis to minimize zonular stress 5
  • If dialysis exceeds 180° significantly, scleral-fixated IOL may be necessary rather than capsular bag or sulcus placement 5

For dialysis 120-180°:

  • Use CTS with scleral fixation aligned to the weakest zonular quadrant 1, 2
  • Modified CTR (m-CTR with suturing eyelets) combined with double-flanged haptic technique provides sutureless fixation option 1

For dialysis <120°:

  • Standard CTR insertion is appropriate and improves outcomes 3
  • Ensure CTR is fully seated within the capsular bag to prevent late decentration 2

Critical Pitfalls and Complications

Early vs Late CTR Decentration Risk

  • Patients with pseudoexfoliation (particularly with associated glaucoma) have high risk of progressive zonulopathy leading to late CTR-IOL-capsular bag complex decentration 2
  • Mean time to late decentration in high-risk patients is approximately 50 months, requiring vigilant long-term follow-up 2
  • Early decentration (mean 6 months) typically indicates inadequate initial zonular support or improper device selection 2

Vitreous Loss Prevention

  • Avoid vitreous loss during surgery, as it is significantly associated with worse postoperative visual outcomes (P=0.008) in zonular dialysis cases 3
  • Gentle surgical technique with complete cortical removal minimizes additional zonular stress 5

Device Selection Errors

  • Do not use standard CTR when dialysis exceeds 120°, as insufficient zonular support will lead to progressive decentration requiring secondary surgical intervention 1, 2
  • Inserting CTR in cases with extensive dialysis (>180°) may cause further zonular damage and complicate subsequent IOL placement 5

Outcomes and Prognosis

  • CTR use is independently associated with improved medium-term BCVA (P=0.004) in zonular dialysis cases 3
  • Successful anatomical repositioning can be achieved in all cases of CTR decentration using scleral suture fixation techniques or CTS placement 2
  • Mean postoperative BCVA improves from 20/100 to 20/40 following appropriate management of zonular dialysis with CTR or CTS 2

References

4
Research

[Capsular bent ring. Improvement of the capsular tension ring].

Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft, 1999

5
Research

The advantages of femtosecond laser-assisted cataract surgery for zonulopathy.

International medical case reports journal, 2019

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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