Figure 10.

ON pathway activity as a stop signal for eye growth. (a) As the eye grows and its axial length approaches the focal length (top), retinal images become sharper, brighter, and more effective at stimulating ON visual pathways. ON visual pathways are strongly stimulated by high spatial frequencies, bright surfaces, eye blinks, and image stabilization circuits that are activated during visual navigation (bottom). Ideally, the eye should stop growing when the retinal response of the ON-pathway is as strong as for the OFF-pathway, a condition that requires retinal images to be sharpest, brightest, and change at the frequency that best activates ON pathways (middle). (b) Reading reduces ON pathway stimulation in the central retina more than in peripheral retina.