ICL Vault Explained: What Counts as a Good Vault, and Why It Changes With Lighting

ICL vault is the gap between the back of an implanted EVO ICL and the front of the eye's natural crystalline lens. It is the single number surgeons watch after surgery — and the outcome every ICL sizing decision is trying to control.

What counts as a good vault?

Conventionally, a good ICL vault is often described as roughly 250–750 microns — comfortably clear of the natural lens without crowding the angle. But the more useful way to think about it is a safe range, not a bullseye:

• Low vault — too little clearance raises the risk of contact with the natural lens and anterior subcapsular cataract.
• High vault — too much can narrow the angle, raising the risk of pigment dispersion, elevated intraocular pressure, and angle-closure.

Why vault is a moving target, not a fixed number

Here is what most sizing discussions miss: vault is not static. In the peer-reviewed study Dynamic Changes in ICL Vault and Anterior Chamber Angle Under Varying Lighting Conditions (Clinical Ophthalmology, 2026), the same eyes measured meaningfully different vaults under photopic (bright) versus scotopic (dark) lighting — mean vault fell by roughly 100 microns from dark to bright as the pupil constricted. In other words, a single postoperative vault reading is one snapshot of a value that moves all day.

That is why chasing one ICL vault measurement in microns is the wrong goal. The right goal is a best-fit lens size that keeps the eye in a safe range across real-world conditions — a subtle but important reframing of what sizing is even for.

How AI predicts vault before surgery

ICL Fit predicts postoperative vault from a non-contact Pentacam / AS-OCT scan, using AI trained on real EVO ICL outcomes — the VAULT and VAULT-OCT research (Journal of Cataract & Refractive Surgery). Rather than committing to a single micron target, it estimates where an eye's vault is likely to land for each lens size, so the surgeon can choose the best fit. For how that compares with traditional tools, see ICL sizing calculators and formulas compared, and for why non-contact imaging is replacing ultrasound, AI ICL sizing without UBM.

Patients researching the procedure can read a plain-language explanation at ICLSurgery.com.