Beta Ray Diagram Widget

How to play

Each eye sees the same square through its correction. A lens changes the image size, so when the two eyes differ the patient sees aniseikonia; in astigmatism the square shears into a rhomboid, differently per meridian. You cannot match every meridian, so the goal is to equalise the spherical-equivalent image size to within 1%. Adjust each eye’s base curve, thickness and index (flatter, thinner, higher index all reduce magnification), or tick Contact lens to idealise that eye to true size. The Rx is the patient — edit it to use this as a tool, or press “New patient” for a fresh puzzle. The drawn size difference is exaggerated 10× so it is visible.

Units:

Left eye (OS)

Right eye (OD)

Both eyes

Ray diagram

Spectacle magnification: two-eye comparisonOD through glasses, SE image -2.02%; OS through glasses, SE image +0.91%. The images differ by 2.9% at the spherical equivalent; adjust lens form to bring them within 1%.Size difference exaggerated 10× for clarity.Aniseikonia 2.9% — match SE within 1%090180090180OS · glasses-0.25 DSSE image +0.91%OD · glasses-2.75 DSSE image -2.02%
OD through glasses, SE image -2.02%; OS through glasses, SE image +0.91%. The images differ by 2.9% at the spherical equivalent; adjust lens form to bring them within 1%.

Readout

OD (glasses) SE image-2.02%
OS (glasses) SE image+0.91%
Aniseikonia (SE)2.93%
StatusNot matched yet