ICL vault, explained — what your number actually means
Clinical framing researched August 2026 · Prices researched July 2026 · Published August 2026
Vault is the clearance between the back of your ICL and the front of your natural lens, and the reference band is roughly 250–750 microns — but the single most useful thing to understand about your number is that it is one point on a moving line. Readings shift with lighting, pupil size, and the measuring device; the implant settles over the first weeks; and vault drifts gently lower over years. A reading outside the band is a finding your surgeon manages — usually by watching the angle and the pressure, occasionally by rotating or resizing the lens — not a verdict you should sentence yourself with at home. This page decodes the band, the drift, the real risks on each side, and the remediation ladder, so the number on your follow-up report stops being a source of 2 a.m. searching.
The gap the surgeon cares about
An ICL does not touch the structures around it — that is the entire trick. The implant sits in the posterior chamber, its haptics resting in the ciliary sulcus, arched over your natural crystalline lens like a bridge over water. Vault is the height of that arch: the vertical clearance, measured in microns on anterior-segment OCT, between the implant's back surface and your natural lens's front surface. Surgeons often anchor it to your central corneal thickness (around 500 µm) — a vault between about half and one-and-a-half corneal thicknesses, roughly 250–750 µm, is the band classically described as ideal.
Why this one dimension gets a dedicated check at every follow-up: it is the geometric summary of how well the lens size matches your eye. Sizing is decided before surgery from measurements of your anterior chamber — it is why the ICL itinerary starts with two days of scans, and why the day-5–7 pressure-and-vault check is the clinical gate that clears you to fly home. Too high an arch crowds the structures in front; too low an arch approaches the lens behind. Everything about vault management follows from those two directions.
Why your number moves — and why that is mostly fine
The threads that keep appearing in patient forums have a common shape: two vault readings, weeks apart, tens or hundreds of microns apart, and a patient concluding the lens is sliding. Before that conclusion, three facts about the measurement itself:
- The reading has noise. Different OCT devices, different operators, and different caliper placements produce genuinely different numbers for the same eye on the same day. A few dozen microns between visits is within the ordinary scatter of the measurement, not evidence of movement.
- The eye is not a fixed stage. Vault changes with pupil size — dim light dilates the pupil and typically increases vault; bright light and accommodation (focusing up close) compress it. A reading taken in a dark imaging room after eye drops is not the same experiment as one taken mid-afternoon without them.
- Early settling is expected. In the first days to weeks the implant finds its resting position as aqueous dynamics equilibrate — early readings commonly shift in either direction before stabilising. Over the long run, studies consistently show vault declining slowly with time, partly because the natural crystalline lens thickens with age and takes up space beneath the arch.
This is why a surgeon reads the trend under comparable conditions rather than reacting to any single number — and why the specific scenario that sent one patient to Quora this month, 1,200 µm at day one becoming 1,350 µm at day fifteen, is early-settling-plus-measurement-scatter behavior first and a migration hypothesis a distant second. High, yes — see the next section. Sliding, almost certainly not.
High vault: what is actually at risk
A vault meaningfully above the band means the arch pushes the iris forward. The two consequences a surgeon actually watches for are both geometric. First, the drainage angle narrows — the outflow channel between iris and cornea loses depth, which in susceptible eyes can raise intraocular pressure. Second, the iris can chafe against the implant's edge, releasing pigment. This is why high-vault follow-up is not a vault measurement repeated anxiously — it is angle imaging (or gonioscopy) plus pressure checks. An eye with a 900 µm vault, a wide-open angle, and normal pressure is an eye most surgeons will simply keep observing, expecting the natural downward drift to do the work.
One design fact belongs here, because it retired the scariest item on the old worry list: every EVO ICL has a 0.36 mm central port (the hole in the middle of the lens) that lets aqueous fluid flow through the implant along its natural path. On pre-EVO generations, blocked flow could cause acute pupillary-block pressure spikes, and surgeons cut a small iris opening in advance to prevent it. The port made that mechanism — and that extra procedure — obsolete, and it is a large part of why modern ICLs tolerate a wide vault band. Since every EVO ICL worldwide is the same STAAR lens, this is one property that does not vary by country or clinic.
Low vault: the other direction
Below the band, the concern flips from the structures in front to the lens behind. A low arch brings the implant close to the natural crystalline lens, and sustained contact is associated with anterior subcapsular cataract — clouding that begins at the front surface of the natural lens. The central port helps here too: it maintains nutrient flow across the crystalline lens's face, and low vaults that would have prompted intervention on earlier generations are now routinely observed, provided a gap remains. The scenario that does prompt action is a vault trending toward zero with imaging showing contact — that is an exchange-for-a-larger-size conversation with your surgeon, not a wait-and-see.
The remediation ladder
| Rung | What it involves | When a surgeon reaches for it |
|---|---|---|
| Observe | Scheduled angle imaging + pressure checks; vault trended under comparable conditions | The default for most out-of-band vaults — angle open, pressure normal, no lens contact |
| Rotate | Repositioning the lens toward the vertically longer diameter of the ciliary sulcus | High vault where geometry suggests the haptics are compressed on the horizontal axis |
| Exchange | Replacing the implant with a different size — same procedure as the original implantation | Persistent high vault with angle/pressure signs, or low vault approaching lens contact |
| Explant | Removal without replacement | Uncommon for vault alone; the reversibility is a design property, not an expectation |
Orientation only — which rung applies to a specific eye, and when, is determined solely by the operating surgeon from imaging and follow-up.
The ladder is worth internalising because it reframes the number. Patients read an out-of-band vault as a countdown to surgery; surgeons read it as an entry on a watchlist with three graded responses available before anything irreversible, and a first rung — observation — on which most cases stay permanently. The question to ask at follow-up is not "is my number normal?" but "what is my angle doing, what is my pressure doing, and what trend are we watching for?" Those three answers are the actual clinical content of vault management.
If your ICL trip is to China: the vault check is the departure gate
Vault is also a trip-planning fact. The 6–7 day ICL itinerary is built around it: sizing scans on days 1–2, surgery, then the pressure-and-vault check on day 5–7 that clears you to fly. Before you leave, make sure your English record set includes the baseline vault measurement with the device named, alongside your endothelial cell count baseline — your home ophthalmologist will trend both for years, and a baseline measured on a named device lets them separate real change from device scatter. The records-to-carry-home list covers the full set. Lifetime monitoring economics — what those annual checks cost and why they are part of ICL's honest price — live on the ICL cost page.
Questions people actually ask
What is a normal vault after EVO ICL surgery?
The reference band most surgeons work with is roughly 250 to 750 microns — about half to one-and-a-half times your corneal thickness of clearance between the back of the implant and the front of your natural lens. It is a band, not a pass-fail line: the EVO ICL's central port lets modern lenses tolerate a wide range of vault, readings shift with lighting and pupil size, and vault normally settles downward over the first weeks and drifts gently lower over years. Whether your specific number is fine for your specific eye is a judgment your surgeon makes from the whole picture — chamber anatomy, drainage angle, and pressure — not from the number alone.
Why is my ICL vault different at every measurement?
Because vault is a live anatomical gap, not an engraved specification. The measurement itself carries device and operator variability; pupil size moves the natural lens and iris geometry, so room lighting, accommodation, and even time of day shift the reading; and the implant genuinely settles during the first weeks after surgery as the eye's aqueous dynamics reach equilibrium. Two readings tens of microns apart may describe an unchanged eye. What your surgeon watches is the trend across visits measured under comparable conditions, alongside pressure and angle status — not the difference between any two single numbers.
Is a vault of 1,200 or 1,350 microns dangerous?
It is above the textbook band, and it is a finding your surgeon manages rather than a number you should panic-interpret at home. What a high vault actually risks is geometric: the implant pushes the iris forward, which can narrow the drainage angle and, in some eyes, rub pigment from the back of the iris. That is why high-vault follow-up centers on gonioscopy or anterior-segment imaging of the angle and on intraocular pressure — if the angle stays open and pressure stays normal, many surgeons observe, because vault typically decreases as the eye settles in the early months and continues a slow decline over years. An early reading that moves — say 1,200 microns at day one and 1,350 at day fifteen — is common measurement-plus-settling behavior, not proof the lens is migrating. If the angle narrows or pressure rises, the remediation ladder exists: rotating the lens or exchanging it for a smaller size are established procedures. The decision belongs to the operating surgeon with your imaging in front of them.
What happens if my ICL vault is too low?
The concern flips: instead of crowding the angle in front, the implant sits close to your natural crystalline lens behind, and sustained contact is associated with anterior subcapsular cataract — clouding that starts at the front surface of the natural lens. The EVO design changed this calculus meaningfully: its central port maintains natural aqueous flow across the crystalline lens, and low vaults that would have worried surgeons on earlier ICL generations are now commonly observed safely, provided a gap remains. A very low vault with actual lens contact is the scenario that prompts an exchange for a larger size. As with high vault, the response is your surgeon's call from imaging, and the practical patient job is keeping follow-up appointments.
Can a high or low vault be fixed without removing the ICL?
Often, yes — and the ladder is more gradual than patients fear. Most out-of-band vaults are simply observed, because they cause no angle narrowing, no pressure rise, and no lens contact. If action is needed, the least invasive step for high vault is rotating the lens toward the vertically longer diameter of the ciliary sulcus, which can lower vault without changing the implant. The next rung is a lens exchange — the same implantation procedure with a different-sized ICL, and reversibility is a genuine design property of the ICL. Full explant without replacement is the last rung and is uncommon for vault reasons alone. Which rung, if any, applies to your eye is determined by the operating surgeon from your anatomy and follow-up imaging.