Capsule Support Devices (Capsular Tension Ring and Segment)

Key Points at a Glance

Highlights of This Disease

• Capsular support devices are a group of instruments used to stabilize the lens capsule during cataract surgery in eyes with zonular weakness or dialysis.
• The four main devices are the standard CTR, modified CTR (Cionni ring), capsular tension segment (CTS), and capsular support hook.
• Indications for CTR are limited to zonular dialysis of about one-third of the circumference (3–4 clock hours) or mild to moderate weakness.
• For dialysis of 4 clock hours or more, or progressive zonular disease, an M-CTR or CTS with scleral fixation is required.
• Exfoliation syndrome (pseudoexfoliation syndrome), trauma, and Marfan syndrome are major risk factors for zonular weakness.
• Long-term postoperative subluxation or dislocation of the IOL-capsule complex has been reported; use of sutured devices is recommended for progressive zonular disease.
• In Japan, the indications for CTR use are defined by the “Guidelines for the Use of Capsular Tension Rings (March 2014 version).“

1. What Are Capsular Support Devices?

Capsular support devices are a group of instruments used to ensure the stability of the lens capsule during cataract surgery in eyes with zonular weakness or dialysis (the supporting fibers connecting the ciliary body and the lens).

When zonular weakness is present, capsular instability occurs during phacoemulsification (PEA), increasing the risk of posterior capsule rupture, vitreous prolapse, and nucleus drop. Capsular support devices prevent these intraoperative complications and enable in-the-bag fixation of the intraocular lens (IOL). Without these devices, surgeons previously had to choose extracapsular cataract extraction (ECCE) or intracapsular cataract extraction (ICCE).

The main devices include the following four types.

• Standard CTR (capsular tension ring): A PMMA C-shaped ring that can be left in the capsule postoperatively. Covered by insurance.
• Modified CTR (M-CTR / Cionni ring): A CTR with eyelets for scleral fixation, used in severe or progressive cases.
• Capsular tension segment (CTS): A partial PMMA ring covering 90–120°. Can also be used in cases with capsular rupture.
• Capsular retention hook: A removable device used to temporarily stabilize the capsule during surgery.

Q Does the CTR remain in the eye after cataract surgery?

A

A standard CTR is placed inside the capsular bag at the end of surgery. In eyes with progressive zonular disease, the IOL-CTR complex may still subluxate postoperatively, so long-term follow-up is necessary.

2. Main Symptoms and Clinical Findings

Subjective Symptoms

Zonular weakness itself is often asymptomatic. When weakness becomes severe, the following symptoms may appear.

• Decreased vision and diplopia: As lens subluxation progresses, multiple refractive surfaces along the visual axis can cause diplopia and vision loss.
• Eye pain and headache: If the subluxated lens causes pupillary block, acute angle-closure glaucoma may develop, resulting in severe eye pain and headache.

Murakami et al. (2024) reported a 68-year-old woman whose IOL-CTR complex dislocated anteriorly 28 months after cataract surgery. The dislocated complex compressed the iris, causing pupillary block and acute angle-closure glaucoma with an intraocular pressure of 80 mmHg. Anterior segment OCT showed forward bulging of the iris and anterior displacement of the IOL-CTR complex²⁾.

Clinical Findings

Preoperatively, zonular weakness is assessed based on the following findings.

• Phacodonesis: Movement of the lens with eye movements.
• Iridodonesis: Tremor of the iris with eye movements.
• Asymmetry of anterior chamber depth: If the anterior chamber depth differs between the two eyes, zonular weakness should be suspected.
• Lens subluxation: As zonular rupture progresses, the lens becomes displaced.
• Asymmetry of angle findings: Gonioscopy may reveal asymmetry of the angle.

Intraoperatively, the following signs often alert the surgeon to zonular weakness or rupture.

• Capsular wrinkling during anterior capsule puncture: When attempting anterior capsule puncture with a cystotome, deep wrinkles extending from the puncture site toward the equator appear.
• Lens movement during CCC: The entire lens wobbles during anterior capsulotomy.
• Abnormal lens oscillation during PEA: Greater-than-normal oscillation occurs during grooving and nuclear division.

Q What to do if zonular weakness is overlooked preoperatively?

A

It is not uncommon to first notice zonular weakness during surgery. It is recommended to use capsular support devices early before zonular weakness or rupture worsens. Once recognized intraoperatively, promptly employ a capsular support device.

3. Causes and Risk Factors

Causes of zonular weakness are broadly divided into congenital and acquired. In preoperative evaluation, it is important to check for the following risk factors.

Risk factors are summarized below.

Risk Category	Representative History/Findings
Systemic diseases	Marfan syndrome, homocystinuria, Weill-Marchesani syndrome
Eye diseases	Exfoliation syndrome, retinitis pigmentosa, uveitis, high myopia
Trauma/surgery history	Ocular trauma, vitrectomy, glaucoma filtering surgery, radial keratotomy
Other	Aging, congenital diseases, atopic dermatitis

Exfoliation syndrome (pseudoexfoliation syndrome, XFS) is one of the most important risk factors. Lysosomal enzymes in exfoliation material produced by ciliary epithelial cells and lens epithelial cells promote degradation of the zonules of Zinn, and the weakening is progressive. It has been reported that during extracapsular cataract extraction, zonular rupture occurs 4 times more frequently in XFS eyes compared to healthy eyes. Additionally, zonular dialysis (ZD) is reported to occur in up to 2.0% of low-risk cases and up to 9.0% of high-risk patients with a history of vitrectomy ³⁾.

The ESCRS guidelines list exfoliation syndrome, high myopia, trauma, cataract surgery, vitrectomy, intravitreal injection, hard nuclear cataract, and retinitis pigmentosa as risk factors for zonular dialysis ³⁾.

Prevention and daily care

Zonular weakness is often associated with progressive diseases, making it difficult for patients to prevent. However, if you have exfoliation syndrome, high myopia, or a history of ocular trauma, be sure to inform your doctor before cataract surgery. Proper evaluation and preparation before surgery can greatly enhance surgical safety.

4. Diagnosis and examination methods

The degree of zonular weakness is assessed through multifaceted evaluation before and after surgery.

Preoperative evaluation

• Slit-lamp microscopy: Check for irregular pupils, exfoliation material deposits, and asymmetry of anterior chamber depth. If there is a history of trauma or surgery, check for lens tremors during eye movement.
• Comparison of sitting and supine positions: It is important to check for changes in lens position due to postural changes.
• Gonioscopy: Evaluate asymmetry of the angle.
• Ultrasound biomicroscopy (UBM) and anterior segment OCT: Useful for visualizing the anatomical state of the zonules. Also used to evaluate anterior displacement of a subluxated lens–CTR complex²⁾.

Zonular Weakness Classification

In Japan, the Zinn Zonule Weakness Classification (ZW classification) based on lens movement during capsulorhexis is used. The device is selected according to the grade from ZW grade 2 (mild weakness) to ZW grade 4 (severe weakness/subluxation).

Indication Criteria

The instrument used is selected according to the degree of weakness.

• Mild to moderate (approximately ≤1/3 circumference rupture): Standard CTR alone.
• Rupture ≥4 clock hours or progressive weakness: M-CTR or CTS (scleral sutured type) is required.

5. Standard Treatment

Selection of Surgical Assist Devices

Surgery for zonular weakness or rupture is challenging. It is considered most important to recognize the findings as early as possible and choose appropriate management; early use before worsening of zonular weakness or rupture is key.

There are three types of lens surgery assist devices, each with different characteristics.

Characteristic	Iris Retractor	Capsule Expander	Capsular Tension Ring (CTR)
Capsular expansion	× (none)	○ (partial)	◎ (circumferential)
Capsular support	○ (point support)	◎ (surface support)	× (none)
Postoperative retention	Not possible (requires removal)	Not possible (requires removal)	Possible
Insurance coverage	None	None	Available

Standard CTR (capsular tension ring)

Material and shape: A C-shaped open ring made of PMMA with blunt eyelets (small holes) at both ends. When placed in the capsular bag, it exerts centrifugal force and redistributes tension from healthy zonular areas to weak or deficient areas.

Indications in Japan (Guidelines for Use of Capsular Tension Ring, March 2014):

• (1) Zinn zonule rupture of approximately 1/3 circumference or less
• (2) Mild to moderate Zinn zonule weakness

Absolute contraindications: Damage or suspected damage to the anterior or posterior capsule. The centrifugal force exerted by the ring on the capsule may enlarge the tear.

Timing of CTR insertion: There are three patterns: “early insertion” (after CCC, before phacoemulsification), “mid insertion” (during phacoemulsification and cortical aspiration), and “late insertion” (before or after IOL insertion). Ideally, the ring should be inserted “as early as necessary, but as late as possible.” Early insertion allows early stabilization of the capsule but may make cortical removal difficult.

Size selection: A properly sized ring has its ends slightly overlapping. The size is selected based on white-to-white distance and axial length. Since there is no clear disadvantage to using a larger ring, it is not unreasonable to use the largest available ring.

Number of capsule expanders (CE) used

A capsule expander (CE) is an intraoperative device used to support the capsular bag in a planar fashion during PEA. The recommended number of expanders is as follows:

• Localized zonular weakness or rupture (e.g., trauma): Approximately 2 expanders in the affected area.
• Circumferential weakness (aging, exfoliation syndrome, etc.): 4 expanders at 90° intervals.
• Cases with pre-existing lens subluxation: 5 expanders.

Modified CTR (M-CTR / Cionni ring)

The M-CTR is a PMMA open ring modified to allow scleral fixation of the CTR, devised by Cionni et al. It has a fixation eyelet support protruding 0.25 mm anteriorly at the midpoint of the ring, which is fixed to the sclera with 9-0 polypropylene or CV-8 GoreTex suture.

Indications:

• Zonular dialysis of 4 or more clock hours
• Progressive zonular disease (e.g., XFS, Marfan syndrome)

Main indications for M-CTR fixation (based on reported cases): Marfan syndrome (40.3%), idiopathic zonular insufficiency (27.2%), post-traumatic (22.8%)⁴⁾. Visual improvement after suture fixation is reported in up to 75.4% of cases⁴⁾.

Risk of suture breakage with M-CTR

The 9-0 polypropylene suture used for scleral fixation may undergo long-term biodegradation. The incidence of suture breakage within 12 months postoperatively is reported to be 0.8–28%⁴⁾, and with 10-0 polypropylene, the breakage rate may reach up to 10% at 1.5 years postoperatively⁴⁾. Additionally, the sharp edges of the M-CTR eyelet may cause chronic wear on the suture, leading to breakage⁴⁾. Patients with suture-fixated M-CTR require long-term follow-up.

Capsular expansion segment (CTS)

CTS is a partial open-ring made of PMMA, shaped like half of an M-CTR. It can fixate the capsular bag over a 90–120° range. Advantages over M-CTR include:

• No rotational insertion required
• Can be used even with anterior or posterior capsule rupture
• Can be used for both intraoperative stabilization and postoperative fixation
• Less likely to trap cortex against the capsular wall than CTR
• Multiple segments can be used in the same eye

Solmaz et al. (2023) reported a 35-year-old woman with secondary angle-closure glaucoma due to microspherophakia. One standard CTR (Morcher type 13) and two Ahmed CTS were scleral-fixated with 9-0 polypropylene, and the IOL was placed in the bag. At 1 month postoperatively, the IOL was well-centered, anterior chamber depth was normal, and intraocular pressure was 10–12 mmHg¹⁾.

Solmaz et al. (2023) reported that the “dual support method” combining CTR with two CTS offers advantages: in-the-bag IOL fixation, prevention of IOL decentration, inhibition of anterior capsule contraction, and reduced risk of capsular complex dislocation¹⁾.

Selection of IOL fixation method

• Mild to moderate zonular weakness, non-progressive tear within 90°: If PEA can be completed using a lens surgery assist device, preserve the capsular bag, fixate the IOL in the bag, and insert a CTR.
• Progressive weakness (aging, exfoliation syndrome, etc.), severe circumferential weakness, tear >90°: Remove the capsular bag and choose ciliary sulcus suturing or intrascleral fixation.

Q Does inserting a CTR prevent future IOL dislocation?

A

With a standard CTR alone, in eyes with progressive zonular diseases such as exfoliation syndrome or Marfan syndrome, there is a risk of postoperative subluxation or dislocation of the IOL-bag-CTR complex. For eyes with progressive disease or extensive tears, use of sutured M-CTR or CTS is recommended.

6. Pathophysiology and detailed pathogenesis

Mechanisms of zonular weakness

The zonules of Zinn are transparent fiber bundles connecting the ciliary body and the lens equator, responsible for lens accommodation and fixation. With aging, fiber elasticity decreases and weakness progresses.

In exfoliation syndrome (XFS), fibrillar pseudoexfoliative material produced by ciliary and lens epithelial cells deposits on the zonules. Lysosomal enzymes in this material promote degradation of the zonular matrix, causing progressive weakness and rupture. XFS-related weakness is progressive and often accompanied by poor pupil dilation and glaucoma.

In Marfan syndrome and homocystinuria, genetic abnormalities in fibrillin-1 cause qualitative abnormalities in the main components of the zonules, leading to extensive zonular defects and lens dislocation.

In microspherophakia, the lens zonules are hypoplastic, elongated, and weak, and the small spherical lens is displaced anteriorly, easily causing pupil block and angle-closure glaucoma¹⁾.

Mechanism of action of CTR

When inserted into the capsular bag, the CTR uses the elasticity of the ring to evenly distribute outward centrifugal force on the capsule. This redistributes the load from intact zonular areas to weak or deficient areas, reducing excessive stress concentration on weak areas. It also maintains the circular shape of the bag, reducing the risk of accidental aspiration during cortical aspiration, and aids in centration of the IOL. Postoperatively, it helps prevent capsular phimosis.

Sutured fixation devices and suture breakage

M-CTR and CTS fix the capsular complex to the ocular wall by scleral suturing. However, long-term in vivo degradation and mechanical wear of the suture (9-0 polypropylene) are problematic. Analysis using scanning electron microscopy (SEM) shows surface degradation of polypropylene sutures within the scleral tunnel, and chronic wear from the sharp edges of the M-CTR eyelet is considered the main cause of suture breakage ⁴⁾. The portion of the suture within the sclera is isolated from the constant flow of aqueous humor and is less susceptible to chemical degradation, but physical friction with the eyelet inside the eye damages the suture ⁴⁾.

7. Latest Research and Future Perspectives

For Patients: Please Read Carefully

The following content is currently under research or in clinical trials and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Improvement of M-CTR Suture Breakage

Currently, to reduce the risk of suture breakage, switching to CV-8 GoreTex (off-label use) or 8-0 polypropylene has been reported. Additionally, design changes to smooth the edges of the M-CTR eyelet have been proposed, and improvement recommendations have been made to the manufacturer ⁴⁾. In vitro tests comparing the wear resistance of sutures and intraocular device edges are considered future challenges ⁴⁾.

New Applications Using CTR

CTR is also applied for the repair of cyclodialysis clefts. Petersen et al. (2021) reported a 38-year-old man with traumatic cyclodialysis cleft who underwent combined surgery: phacoemulsification, CTR placement, intraocular lens insertion, vitrectomy, and 22% SF6 gas tamponade. Hypotony resolved about one month postoperatively (postoperative IOP 14 mmHg), and BCVA recovered to 20/25 after three months ⁵⁾. The mechanism is thought to be that the CTR-supported capsule presses the ciliary body against the scleral spur in synergy with gas pressure ⁵⁾.

Fish-Tail Technique

A recently reported “fish-tail technique” does not require conventional injector insertion or rotational insertion, potentially reducing stress on the zonules.

Q What symptoms occur if the suture breaks?

A

When suture breakage occurs, the capsular complex including the M-CTR or CTS and IOL becomes subluxated or dislocated. This leads to decreased vision, diplopia, and IOL decentration. Rarely, the IOL-CTR complex may shift anteriorly, causing pupillary block and acute angle-closure glaucoma ²⁾. Prompt ophthalmologic consultation is necessary.

8. References

1. Solmaz N, Oba T, Onder F. Combined Capsular Tension Ring and Segment Implantation in Phacoemulsification Surgery for the Management of Microspherophakia with Secondary Angle-Closure Glaucoma. Beyoglu Eye J. 2023;8(2):123-127.

2. Murakami K, Sugihara K, Shimada A, Iida M, Tanito M. A Case of Acute Angle Closure Secondary to Pupillary Block Caused by a Dislocated Intraocular Lens-Capsular Tension Ring Complex. Cureus. 2024;16(11):e72963.

3. ESCRS Cataract Guideline. Section 9.2 Adverse events during cataract surgery. European Society of Cataract and Refractive Surgeons; 2023.

4. Anisimova NS, Arbisser LB, Shilova NF, Kirtaev RV, Dibina DA, Malyugin BE. Late dislocation of the capsular bag-intraocular lens-modified capsular tension ring complex after knotless transscleral suturing using 9-0 polypropylene. Digit J Ophthalmol. 2020;26:8-16.

5. Petersen EL, Blieden LS, Newman TM, Lin AL. Combined phacovitrectomy with capsular tension ring and gas tamponade for chronic cyclodialysis cleft unresponsive to conventional closure. Taiwan J Ophthalmol. 2021;11:296-299.