Beta Ray Diagram Widget

How to play

The goal is to neutralize the eye. This eye has a random refractive error, so parallel light from a distant object focuses off the retina. Tick “Place a correcting lens”, then set its power and its distance from the cornea until the residual error reaches 0.00 D and the light focuses on the retina. A minus lens corrects myopia; a plus lens corrects hyperopia. Set the distance to 0 mm for a contact lens, or move it out (e.g. 12 mm) for spectacles — watch how the power you need changes with distance (the vertex effect). Tick “Solve at 12 mm vertex” to reveal the spectacle answer, or “New Eye” for a fresh puzzle.

Ray diagram

Readout