Formula Comparison
SRK/T vs Barrett Universal II — When Does Formula Choice Actually Matter?
For average eyes, formula differences are modest. At the extremes of axial length, selection has a measurable effect on outcomes.
IOLDx Clinical · PubMed-based · May 17, 2026
Post-Refractive
Post-Myopic LASIK IOL Calculation — Why Standard Keratometry Misleads
Myopic LASIK creates an oblate cornea that breaks standard IOL formula assumptions. The mechanism, the error, and how to correct it.
IOLDx Clinical · PubMed-based · May 17, 2026
Toric Planning
Toric IOL Rotation — Alignment, Stability, and Residual Astigmatism
Each degree of misalignment reduces effective cylinder correction by roughly 3.3%. Posterior corneal astigmatism and SIA matter as much as axis marking.
IOLDx Clinical · PubMed-based · May 17, 2026
FDA Data
Defocus Curves Explained — What FDA SSED Data Actually Shows
FDA SSED documents provide high-quality trial data, but cross-platform comparisons require caution. How to read a defocus curve correctly.
IOLDx Clinical · PubMed-based · May 17, 2026
Formula Comparison
Formula Selection in Short Eyes — What the Evidence Actually Shows
For eyes below 22mm, Hoffer Q has a strong evidence base. Modern formulas including Barrett and Kane are competitive. Nanophthalmos is a separate category.
IOLDx Clinical · PubMed-based · May 17, 2026
Surgeon Constants
Haigis a0, a1, a2 — What the Three Constants Actually Do
a0 is a global offset. a1 and a2 are regression terms weighting ACD and AL. Understanding the difference determines how to optimize them.
IOLDx Clinical · PubMed-based · May 17, 2026