| Drag | orbit the camera (right-drag or Shift-drag pans, scroll zooms) |
| Drag glowing handles | move the light source, object arrow, screens, bench parts |
| 1–8 | jump to a chapter |
| Tab / arrows | move between sliders and adjust them — every draggable thing also has a slider, so everything is reachable by keyboard (camera orbit is mouse/touch; number keys work when a slider isn't focused) |
| R / Shift+R | reset module / reset everything |
| ? | show or hide this help · Esc closes |
Every ray is traced live — nothing is pre-drawn. Flat and curved glass surfaces use Snell's law; the idealized thin lenses (the eye model, astigmatism, sandbox) use the standard paraxial lens rule, and each module says which it uses. Break the focus, then fix it.
Built by Central Ohio Vision and Eyecare in New Albany, OH. Curious about your own prescription? Call (614) 933-0575 or schedule an exam.