Cataract Surgery · Surgeon & Patient Series
Five millimetres,
torn by hand,
in a single circle.
Before a cataract can come out, the surgeon has to open the front of the bag that holds it. How that opening is made, and how big and well-centred it is, shapes almost everything that follows: how safely the cataract is removed, where the new lens sits, and how likely the vision is to cloud again later.
a 6 mm optic
on the optic
formally described
Section 01 — The Opening
A window into the bag,
and why it must be round.
The eye's lens sits inside a thin, elastic capsule. In modern cataract surgery the surgeon opens a round window in the front of that capsule, removes the cloudy lens through it, and leaves the rest of the bag behind to hold the artificial lens. That window is the capsulorhexis.
The technique that made it reliable is the continuous curvilinear capsulorhexis (CCC): instead of perforating the capsule in a ring of small cuts (the older "can-opener" capsulotomy), the surgeon tears one smooth, continuous circular edge. Howard Gimbel and Thomas Neuhann described its development, advantages and methods in 1990. Their key point still holds: a continuous edge has no notch for a tear to start from, so the rim resists tearing even when it is stretched during nucleus removal and lens implantation.
A capsulorhexis is the round opening a cataract surgeon tears in the front of the lens capsule. Done as a continuous curvilinear capsulorhexis, it leaves a smooth, strong edge that resists radial tears, allows hydrodissection and phacoemulsification inside the bag, and keeps the bag intact to hold the intraocular lens. For a typical 6 mm optic, surgeons aim for an opening a little smaller than the optic, roughly 5 mm and well centred, so that the capsule edge rests on the optic all the way round. That 360-degree overlap helps keep the lens centred and is associated with lower rates of posterior capsule opacification. When there is no red reflex, trypan blue stains the capsule so the edge can be seen.
Section 02 — Interactive
Size and centration:
where the edge
meets the lens.
Surgeons talk about "overlap": whether the cut edge of the anterior capsule sits on top of the IOL optic all the way round. Change the diameter and the centration below.
Two lessons fall out of the geometry. First, a well-centred opening a little smaller than the optic covers its edge all the way round, but even a modest decentration can uncover one side. Second, smaller is not automatically better: very small openings make nucleus removal harder and are associated with the capsule contracting later (capsular phimosis), especially in eyes with weak zonules such as pseudoexfoliation.
Section 03 — When It Gets Hard
No red glow,
a swollen lens,
a capsule that runs.
In a routine eye the surgeon watches the edge against the orange-red reflex from the retina. The capsulorhexis becomes difficult when that view disappears or when the capsule is under tension.
| Situation | Why it is hard | Common approach |
|---|---|---|
| White or mature cataract | No red reflex; the edge is hard to see | Stain the anterior capsule with trypan blue |
| Intumescent (swollen) white cataract | Pressure inside the lens can split the capsule radially the moment it is opened: the "Argentinian flag sign" | Stain, deepen the chamber with OVD, and decompress the lens before completing the circle |
| Shallow chamber | The lens pushes forward; the flap tends to run outwards | A cohesive viscoelastic to flatten the capsule and deepen the chamber |
| Weak zonules | The bag moves as the surgeon pulls | Careful counter-traction; consider a capsular tension ring |
| Children | The capsule is highly elastic and tends to extend | Modified techniques; vitrector-cut openings in some cases |
Trypan blue was introduced for exactly this problem. Melles and colleagues reported in 1999 that 0.1 mL of trypan blue 0.1% stained the anterior capsule in 30 patients with mature cataract, allowing the capsulorhexis to be seen, with no adverse reactions up to 12 months. Staining is now a standard step whenever the red reflex is poor.
The intumescent white cataract is the hardest case. Figueiredo and colleagues described why the capsule tears: the lens holds pressurised compartments, and the pressure that pushes the nucleus upward comes from inside the lens rather than from the vitreous. Decompression approaches aim to release that pressure first. In a 2021 series from PGIMER Chandigarh, Balyan and colleagues combined a partial-size main port, needle decompression of the intralenticular compartments and a trypan-blue-stained capsule, and achieved a standard-size, circular, centred CCC in all 60 eyes, with no Argentinian flag sign.
Section 04 — Rescue
If the edge runs,
pull it back.
Sometimes the tearing edge starts to head outwards towards the equator of the bag. If it reaches the periphery it can extend around to the back of the capsule, which is how a front-of-bag problem becomes a posterior capsule rupture.
The first response is to stop and refill the chamber with viscoelastic to flatten the capsule and relieve the outward pressure. The best-known manoeuvre is the one Brian Little, Jennifer Smith and Mark Packer published in 2006: unfold the flap and pull it backwards, against the direction of the tear, so that the tearing force redirects the edge back towards the centre. If the edge still cannot be brought back, surgeons often restart the tear from the other side, or complete the opening with scissors, and then take extra care with fluid pressure and nucleus rotation for the rest of the case.
Section 05 — Hand or Laser
Forceps, needle
or femtosecond laser.
The tear can be started and guided with a bent needle (cystotome), with fine capsulorhexis forceps, or the opening can be cut by a femtosecond laser before the surgeon enters the eye.
| Method | Strengths | Limits |
|---|---|---|
| Cystotome (needle) | Works through a small incision; inexpensive; widely used in high-volume surgery | Relies on the surgeon's control of the flap |
| Capsulorhexis forceps | Fine grip and control of the flap throughout | Needs a wound large enough for the forceps tips |
| Femtosecond laser | Programmed size and centration; very round openings | Cost, extra equipment and time; see our FLACS guide for how outcomes compare |
Whatever the instrument, the chamber has to stay formed while the capsule is opened. That is the job of the ophthalmic viscoelastic. Cohesive OVDs are favoured for this step because they hold space and press the capsule flat; the trade-offs between cohesive and dispersive products are set out in our OVD rheology guide.
Section 06 — For Patients
What it means
for you.
You will not feel the capsulorhexis or see it happen. It is one step within an operation that usually takes 15 to 30 minutes under local or topical anaesthesia (see cataract surgery explained).
Where it matters to you is afterwards. A well-sized, centred opening helps the lens stay centred and supports clear vision over time. If your vision becomes hazy months or years later, the usual cause is posterior capsule opacification, which is treated with a quick YAG laser procedure in clinic. If your surgeon mentions a "difficult rhexis" or a "tear", ask what it meant for the lens position and what follow-up you need; most such operations still end with a well-placed lens and good vision.
Section 07 — The Agaaz Range
What sits in the tray
for this step.
Agaaz Ophthalmics does not make capsulorhexis forceps, cystotomes or femtosecond lasers. Our connection to this step is the consumables used around it, GMP-manufactured in India, and the lenses the finished opening has to hold.
Section 08 — FAQ
Frequently asked questions
about capsulorhexis.
A capsulorhexis is the round opening a cataract surgeon makes in the front of the lens capsule, the thin bag that holds the eye's natural lens. The cloudy lens is removed through this opening and the intraocular lens is then placed inside the remaining bag. The standard technique is a continuous curvilinear capsulorhexis (CCC), which leaves one smooth edge.
A continuous edge has no notch where a tear can start, so it resists splitting when the capsule is stretched during nucleus removal and lens implantation. The older can-opener method left a ring of small cuts, each of which could extend into a radial tear.
For a typical 6 mm IOL optic, surgeons usually aim for a well-centred opening a little smaller than the optic, often around 5 to 5.5 mm, so the capsule edge overlaps the optic all the way round. Very small openings make surgery harder and are linked to capsule contraction later; large or decentred ones leave part of the optic edge uncovered.
Overlap matters. A pathology study of 457 eyes found that eyes needing YAG laser treatment for posterior capsule opacification had more clock hours where the rhexis edge did not overlap the optic, and concluded that a relatively small CCC covering the entire optic rim was best for reducing the YAG rate.
In white or mature cataracts there is no red reflex from the retina, so the edge of the capsule is hard to see. Trypan blue stains the anterior capsule blue so the surgeon can see and control the tear. It was described for this purpose by Melles and colleagues in 1999.
It is a sudden radial split of the anterior capsule that can happen when a swollen (intumescent) white cataract is opened, because pressure inside the lens pushes the capsule apart. Surgeons reduce the risk by staining the capsule, deepening the chamber with viscoelastic and decompressing the lens before completing the opening.
A femtosecond laser can cut a very round opening of a set size and centration, but a well-made manual capsulorhexis also gives excellent results, and most cataract operations worldwide use the manual technique. Whether the laser improves overall outcomes enough to justify its cost is covered in our FLACS guide.
Section 09 — References & Sources
Sources and
evidence.
All references were checked against PubMed for this article.
Section 10 — Continue Reading
Related guides
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Capsulorhexis in Cataract Surgery: Why a 5 mm Circle Decides So Much — Size, Centration, Trypan Blue & Tear Rescue (2026 Guide)