haigis l calculator - Aaron Graves, PhDude Replica

Haigis-L Calculator (Educational Tool)

Use this calculator to estimate adjusted corneal power (Haigis-L style) and a rough IOL power estimate. It is intended for learning and planning discussions—not for final surgical decisions.

Measured Corneal Radius (mm)

Typical range: 6.80 to 9.20 mm

Axial Length, AL (mm)

Anterior Chamber Depth, ACD (mm)

Haigis Constant a0

Haigis Constant a1

Haigis Constant a2

Target Refraction (D)

Example: emmetropia = 0.00, mild myopia target = -0.50

Formulas used in this page:
K_measured = 337.5 / r
K_adj = -5.1625 × r + 82.2603
ELP = a0 + (a1 × ACD) + (a2 × AL)
IOL (estimate) = [1336/(AL − ELP)] − [1336/((1336/K_adj) − ELP)] − Target

What is the Haigis-L method?

The Haigis-L method is a post-refractive cataract planning approach commonly used when a patient has had prior myopic LASIK or PRK. After corneal refractive surgery, standard keratometry often overestimates corneal power in a way that can lead to hyperopic surprises if uncorrected. Haigis-L addresses this by applying a corneal power adjustment and then using a vergence-based IOL calculation framework.

When this calculator is useful

Educational review of post-LASIK IOL planning concepts
Quick comparison between measured and adjusted keratometry
Generating a rough lens power estimate to discuss with clinicians

Important note

This page is a learning calculator. Real surgical planning should use optimized device-specific constants, biometer data, surgeon outcomes, and multiple formulas (for example Barrett True-K, Haigis-L, Shammas, ray tracing, and intraoperative aberrometry when appropriate).

How to use this Haigis L calculator

Enter measured corneal radius in millimeters.
Enter AL and ACD from your biometry report.
Use surgeon-optimized Haigis constants (a0, a1, a2) whenever available.
Set your target refraction.
Click Calculate and review adjusted K, ELP, and estimated IOL power.

Input guide

Corneal Radius

Radius is used to estimate measured keratometry and then transformed to an adjusted post-refractive value. Small changes in radius can shift final IOL power noticeably.

AL (Axial Length)

AL is one of the strongest predictors in IOL power formulas. Ensure high-quality scans and repeatability, especially in long eyes.

ACD and Haigis constants

Haigis-style calculations rely on estimated effective lens position (ELP). This page computes ELP from ACD and constants a0/a1/a2. If constants are not optimized, the estimate can drift.

Practical tips for better accuracy

Compare outputs from several modern formulas, not just one.
Prefer surgeon-optimized lens constants from real outcomes.
Use consistent biometry devices when tracking performance.
Discuss realistic refractive expectations with patients.

FAQ

Is this a medical device?

No. It is a web-based educational estimator and should not replace professional clinical planning software or physician judgment.

Why does the rounded value differ from the raw value?

IOLs are usually selected in 0.50 D increments. This calculator shows both a raw estimate and a nearest 0.50 D lens suggestion.

Can I use this after hyperopic LASIK?

Use caution. Formula behavior can differ by prior procedure type and eye characteristics. Always verify with a clinician and multiple validated methods.