Capsular tension rings: when lens supports are weak
A capsular tension ring is a fine, flexible ring placed inside the lens capsule during cataract surgery. It helps support the capsule when the tiny fibres holding it in place are weak or partly missing. It is particularly useful in selected eyes with pseudoexfoliation, but it is not needed for every patient with this condition.
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What does the ring support?
The natural lens sits inside a thin, transparent bag called the lens capsule. Fine fibres called zonules suspend this bag inside the eye. During cataract surgery, the cloudy lens is removed through an opening in the front of the capsule, while the rest of the bag is usually retained to hold the new lens implant.
When people describe a ‘weak lens’, they often mean that its supporting zonules are weak. The bag may move or lose its usual shape as the cataract is removed.
A standard capsular tension ring, or CTR, is an open C-shaped ring, usually made from clear PMMA plastic. It sits around the outer edge of the bag and distributes support across the remaining zonules, helping the capsule keep a more even shape.
Is it the same as a lens implant?
No. The ring supports the bag; the intraocular lens (IOL) focuses light. They have different jobs and can both remain in the capsule after surgery.
The ring has no focusing power and does not determine whether you need glasses afterwards. That discussion is part of choosing a lens implant. A standard ring is also different from a temporary pupil-expansion ring, which holds a small pupil open during surgery.
Why is it used in pseudoexfoliation?
In pseudoexfoliation, flaky material accumulates on structures inside the eye, and the zonules can become fragile. The pupil may also dilate poorly, and eye pressure needs attention. These are separate issues: a capsular tension ring supports the capsule but does not enlarge the pupil or treat glaucoma.
If zonular weakness makes the capsule unstable, a ring can provide useful support during cataract removal and lens implantation. Weakness may be recognised before surgery or become apparent during the operation. Other causes include previous eye injury and some inherited conditions affecting the lens supports.
Pseudoexfoliation alone does not automatically mean a ring is necessary. A small randomised study found fewer zonular separations during surgery with a ring. More recent ten-year research in uncomplicated pseudoexfoliation without obvious lens wobble or a very small pupil did not show an advantage from adding one routinely. Those results do not settle the question for eyes with clear zonular weakness.
How is the ring inserted?
The surgeon gently guides the ring into the capsule through the cataract incision. Its position and timing depend on how stable the bag is and which parts of the cataract have already been removed. Inserting it earlier can support the bag, but can also make removal of the remaining soft lens material more difficult.
The short video below shows Dr Simon Chen using a Sinskey hook, a fine instrument with a small hooked tip, to help control the ring as it enters the bag. Controlled insertion matters because the capsule and its supporting fibres are delicate. The video demonstrates a technique; it does not compare complication rates.
Surgical footage · 0:58 · Watch on YouTube
What can a standard ring not do?
A standard ring does not replace missing zonules or attach the bag to the wall of the eye. If too much support is lost, or the weakness is progressive, the surgeon may need temporary capsular supports, a specialised ring or segment that can be secured with a suture, or a different way of fixing the lens implant.
The condition of the capsule matters too. A tear may make a standard ring unsuitable, and insertion itself can place stress on the remaining zonules. The decision is based on the whole eye, rather than simply the diagnosis of pseudoexfoliation.
A ring cannot guarantee that the lens implant will remain centred for life. In pseudoexfoliation, zonular weakness can progress and the capsule, ring and lens implant can occasionally shift together years later. Reports of this complication show that it is possible; they do not establish how often it will happen to an individual patient.
What does having a ring mean afterwards?
The ring is normally left in the eye permanently. You do not usually feel it, and it does not need routine replacement. Drops, activity advice and review depend on the cataract operation and any other treatment performed, rather than on the ring alone. The cataract recovery guide explains general aftercare.
Follow-up remains important, particularly with pseudoexfoliation. Your eye-care team can check eye pressure, the lens position and whether the capsule is tightening. New or worsening vision after an initially good recovery should be assessed rather than assumed to be a normal effect of the ring.
What is useful for patients and optometrists to discuss?
Before surgery, tell the surgeon about known pseudoexfoliation, previous eye injury or any history of lens instability. For optometrists, useful referral findings include lens wobble (phacodonesis), poor pupil dilation, raised pressure and previous trauma. The extent of zonular weakness may only become clear during surgery.
A useful patient question is: ‘Are my lens supports weak, and what support might be needed during surgery?’ Afterwards, recording whether a ring or another fixation device was used helps future clinicians interpret the eye’s anatomy and plan follow-up.
Sources and further reading
- Bayraktar et al. (2001). Capsular tension ring implantation in pseudoexfoliation.
- Haripriya et al. (2025). Aravind Pseudoexfoliation Study: 10-year results.
- Ozturk & Gunduz (2021). Optimal timing of capsular tension ring implantation.
- Lorente et al. (2010). Late in-the-bag intraocular lens dislocation.
- NICE NG77. Cataracts in adults: management.
- FDA. Capsular tension ring device assessment.