A Model of the Human

We describe a model of the human eye that incorporates a variable converging lens. The model can be easily constructed by students with low-cost materials. It shows in a comprehensible way the functionality of the eye’s optical system. Images of near and far objects can be focused. Also, the defects of near and farsighted eyes can be demonstrated. A commercial product is available for demonstrat-ing the optics of the eye.1 This model is based on the Ingersoll Eye Model, which was sold by Cenco and is apparently no longer available. However, this model does not have the variable lens capability. One with a variable lens is quite expensive.2 Functionality of the Eye The task of the eye’s optical system is to create an optimal sharp image of the external world on the reti