• Background
  • Instructions
  • Illustration
  • Quiz


The lens has its maximal flexibility when we are young. As we age, the lens becomes more rigid. Since the flexibility of the lens is crucial to accommodation, this loss of flexibility causes us to lose some of our ability to accommodate. More specifically, we lose the ability to thicken the lens so we can see more closely. As a result, we lose the ability to see close objects clearly, leading adults to need extra aids to read—reading glasses, bifocals and the like.


Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab


Below is a list of the ways that you can alter the illustration. The settings include the following:

Light Position: moves the light closer or farther from the eye.
Turn Light On: Pressing this button will start the light. Pressing the button again removes the light.
Make Eye Presbyopic: When checked, the lens of the eye becomes presbyopic.


Pressing this button restores the settings to their default values.