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Alpins Vectors · ORA · Vector Planning

TREAT THE SOURCE OF THE CYLINDER — NOT JUST THE NUMBER.

Written by the RLES AI clinical rules team · Medically reviewed by Fırat Helvacıoğlu, MD · Ercüment Bozkurt, MD · Last updated: 20 August 2026

The manifest cylinder is a sum, not a source. When the cornea and the crystalline lens disagree, treating the sum on the cornea carves today’s lens into tomorrow’s problem.[3] RLES AI separates the components before the profile is chosen.

ALPINS VECTORS AND OCULAR RESIDUAL ASTIGMATISM

Using Alpins double-angle vector analysis,[1] RLES AI decomposes refractive and corneal astigmatism into power vectors and computes the ORA — the internal, mostly lenticular component. Graded bands (0.75 D, 1.00 D, and the ORA-to-cylinder ratio ≥ 1.0) decide when standard planning suffices and when source analysis is mandatory; published data show refractive efficacy declining as ocular residual astigmatism rises.[2] In older patients with high lenticular contribution, RLES AI Mobile Interfacelies a 60/40 vector-planning split — a Level D operating rule of ours, not a published guideline — to protect the cornea from a correction that will outlive the lens it compensated.

THE RIGHT MODE ON YOUR PLATFORM

  • Contoura / T-CAT on the WaveLight EX500 — requires Topolyzer VARIO capture, with the published acquisition protocol enforced
  • ORK-CAM corneal or ocular wavefront on SCHWIND AMARIS — SIRIUS+ or Peramis, with the adjusted-refraction method for CW-guided plans
  • OCTAVIUS TG and ZYOPTIX HD on the TENEO 317 (licence-checked), TOSCA/WASCA on Zeiss MEL via CRS-Master
  • If the required diagnostic device is not registered in your clinic, the mode is not proposed — capability is never assumed

FROM ANALYSIS TO THE PLANNING SCREEN

Every WFG/TG report ends with a "values to enter on the planning screen" block — the numerical sphere/cylinder/axis of the vector solution, the mode to select, and the device constraints — plus a double-angle vector diagram per eye. You can even send a photo of the planning screen before confirming: entered values are checked against the report, and any mismatch is flagged before surgery.

FREQUENTLY ASKED QUESTIONS

When is topography-guided planning preferred over manifest refraction?
When ocular residual astigmatism is high or the refractive and corneal axes diverge — RLES AI computes the Alpins vectors and flags exactly these cases with graded thresholds.
What is ocular residual astigmatism (ORA)?
The vector difference between the eye’s total refractive astigmatism and its corneal astigmatism — the part that does not live on the cornea. Treating the manifest cylinder fully on such a cornea leaves a predictable residual error.
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. Alpins NA. Astigmatism analysis by the Alpins method. J Cataract Refract Surg. 2001;27(1):31-49. doi:10.1016/S0886-3350(00)00798-7 PMID: 11165856
  2. Frings A et al. LASIK for spherical refractive myopia: effect of topographic astigmatism (ocular residual astigmatism, ORA) on refractive outcome. PLoS One. 2015;10(4):e0124313. doi:10.1371/journal.pone.0124313 PMID: 25875476
  3. Stulting RD, Durrie DS, Potvin RJ et al. Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods. Clin Ophthalmol. 2020;14:1091-1100. doi:10.2147/OPTH.S244079 PMID: 32425495
Sources open on PubMed in a new tab.
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