Figure 5.

Interaction of the eye-size mechanism with visual guidance. Minus lens wear or form deprivation produces an increased axial length, relative to normal. If treatment is continuous, the emmetropization mechanism maintains the increased length. If the visual input to the emmetropization mechanism is interrupted by even brief periods of unrestricted vision, the eye-size factor causes a return toward the normal axial length. Continuous plus-lens wear produces, and maintains, a shortened axial length. If the visual guidance is interrupted, the eye-size mechanism causes a return toward the normal axial length. A color version of this figure is available online at www.optvissci.com.