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ACD CONVERTER FOR PHAKIC ICL

Written by the RLES AI clinical rules team · Last updated: 7 September 2026

The ICL indication is written from the corneal endothelium to the anterior lens surface. Devices do not all report that distance — and the difference is larger than the threshold itself.

ACD CONVERTER FOR PHAKIC ICL

ACD from endothelium
Correction applied
International practice
FDA on-label

Nothing is stored or transmitted — the calculation runs entirely in your browser. For professional use by eye surgeons; it is not a diagnosis and does not decide whether surgery may be performed. One number is not a plan: RLES AI audits about 300 items in a single laser case. See what one plan actually requires →

THE MEASUREMENT TRAP MATTERS MORE THAN THE THRESHOLD

Pentacam reports ACD internal from the endothelium and ACD external from the epithelium; Orbscan separates endo and epi; optical biometers of the IOLMaster type measure from the epithelium and therefore read roughly one corneal thickness — about 0.5 mm — higher. Anterior chamber depth measurements from partial coherence interferometry, Scheimpflug imaging, OCT and ultrasound biomicroscopy have been shown to differ significantly and not to be interchangeable.[1] An uncorrected epithelium-referenced reading can overstate the chamber by more than twice the margin between the two thresholds in common use.

THE TWO THRESHOLDS IN USE

  • 3.00 mm — the on-label figure, measured from the corneal endothelium to the anterior crystalline lens surface
  • 2.80 mm — widely used in international practice for myopic cases; shallower chambers are implanted where the angle is fully open, but that decision rests on anterior segment imaging of the sulcus and ciliary body, not on this arithmetic

Beyond depth, candidacy involves indication ranges, an age band, and an endothelial cell requirement that the manufacturer's directions state as an age-indexed minimum. Three-year outcomes from the EVO/EVO+ multicentre study reported mean endothelial cell loss of 6.7% at three years.[2]

WHAT THIS PAGE DOES NOT DO

It converts one distance. It does not size a lens, predict vault, or establish candidacy. RLES AI's screening module applies the indication ranges, the age band, the endothelial requirement, the keratoconus screen and the region-specific label status together — and refuses to convert at all when pachymetry is missing, rather than estimating it. See phakic ICL screening.

FREQUENTLY ASKED QUESTIONS

Why does ACD have to be measured from the endothelium?
Because the indication is written that way: from the corneal endothelium to the anterior surface of the crystalline lens. A reading taken from the epithelium includes the corneal thickness and overstates the chamber.
How much difference does the reference surface make?
Roughly one corneal thickness — about 0.5 mm in an average eye. That is more than twice the 0.20 mm margin between the two thresholds in common use, so the error changes the answer, not just the number.
What if central corneal thickness is not available?
The conversion cannot be performed. RLES AI marks ACD as missing rather than estimating a pachymetry value — a missing input is never assumed.
Is 2.80 mm or 3.00 mm the correct threshold?
3.00 mm is the on-label figure; 2.80 mm is widely used in international practice for myopic cases. Shallower chambers are implanted in selected eyes, but that decision requires anterior segment imaging of the sulcus and ciliary body and a vault prediction, not geometry alone.
SEE IT ON YOUR OWN CASES.
RLES AI runs as a mobile interface on your phone — nothing to install from a store, reports in minutes. The final clinical decision always rests with the surgeon.

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References — peer-reviewed sources
  1. Nakakura S, Mori E, Nagatomi N, Tabuchi H, Kiuchi Y. Comparison of anterior chamber depth measurements by 3-dimensional optical coherence tomography, partial coherence interferometry biometry, Scheimpflug rotating camera imaging, and ultrasound biomicroscopy. J Cataract Refract Surg 2012;38:1207-13. PMID: 22613688
  2. Parkhurst G, Brinton JP, Faulkner A et al. Three year results from the United States FDA prospective multicenter clinical study of the EVO/EVO+ implantable collamer lens. Clin Ophthalmol 2025;19:3237-48. PMID: 40937096
Sources open on PubMed in a new tab.