Calculate New Arc Length

Original arc → incision → new arc for ~0 residual astigmatism

① Astigmatism & Original Arc

Corneal astigmatism (Betrag, präop)

Steep axis (= original LRI axis, 0–180°)

Patient age (for the nomogram)

Original arc length (automatic from the nomogram)

–

Nomogram table (reference) · Castrop/Hoffman

Arc length (°) by age × cylinder. Active cell = current input. Formula: effect = −2.4699 + 0.0610·arc + 0.0155·age. Validated: arc 30–60°, age 40–90, cyl. 0.5–2.5 D.

② Clear Corneal Incision

Incision width

Incision axis (position on the eye, 0–360°)

Induced cylinder = fixed value based on width (table). Values adjustable to your own centroids.

New recommended arc length

Set the inputs above and press the button.

LRI arc Ø 8.5 mm · 80 % · nomogram slope ≈ 16°/D · Refractive Planning Suite · Dr. H. C. Gäckle