ToricTrouble

Working up a toric IOL outcome: which lens is really at work, which cornea fits it, and what neither explains. Four positions, CAS Rx calculation core.

Toric Trouble works up the outcome after a toric intraocular lens. The app calculates backwards: from biometry, implanted lens and subjective refraction it determines which of the three does not fit the other two.

FOUR POSITIONS

• Lens — which lens is actually at work? The main clinical question. • Refraction — what refraction was to be expected? Turning the axis simulates a misaligned lens. • Cornea — which cornea fits lens and refraction? Comparing it with the keratometry is the diagnosis. • Plausibility — all three checked against each other, naming the ghost astigmatism: what none of the three explains.

FURTHER FEATURES

• A recommendation where to rotate, what residual cylinder would remain at best — and whether an exchange is the better choice • Axis diagrams with uncertainty wedges from the actual measurement tolerances: cornea 0.30 D vectorial, refraction 0.25 D, read-off axis ±3° • Keratometric index selectable in four steps: 1.3375 (Javal), 1.332 (Zeiss), 1.3295 (Kooijman), 1.3281 (Liou & Brennan) • Effective lens position from the postoperatively measured anterior chamber depth instead of a prediction — this removes the largest uncertainty from the calculation • Surgically induced astigmatism (SIA) from pre- and postoperative keratometry • Plausibility check on every entry: impossible values block the calculation rather than yielding a result that looks like any other • Complete manual inside the app, in three languages

CALCULATION CORE

The basis is the Castrop formula, developed with Prof. Achim Langenbucher, Saarland University, and published peer-reviewed:

Langenbucher A et al. Considerations on the Castrop formula for calculation of intraocular lens power. PLoS One 2021;16(6):e0252102 Langenbucher A et al. The Castrop formula for calculation of toric intraocular lenses. Graefes Arch Clin Exp Ophthalmol 2021;259(11):3321–3331

Both papers are linked inside the app, directly below the result. Where the app goes beyond what is published, it says so and describes the calculation path in full in the bundled manual.

All calculation runs on the device, in C99 compiled into the binary. No account, no sign-in, no network, no advertising, no data collection. German, English and Italian.

For ophthalmologists and other eye care professionals. Not a medical device; responsibility for every clinical decision remains with the user.