exhibit consists of four MODEL EYEBALLS that are about 10 times
human size. The models represent a nearsighted eye, a farsighted
eye, an eye with an adjustable focal length, and an astigmatic eye.
All but the adjustable eye are provided with external corrective
lenses that can be added or removed by the visitor. There are nearby
and distant objects for the eyes to focus on. Real images are formed
on the back of each model, revealing the image inversion which takes
place in the eye as well as the corrective effect of lenses.