Fixation is the ability to direct and maintain steady, central visual attention on a target. This basic skill is developed in infancy and refined through the early years. The infant reflexively turns the entire upper torso toward the direction of a noise, then gradually learns to turn only the head to guide the visual system. Through the toddler years the individual refines this movement system by learning to use eye muscles to replace head movement - an achievement important in visual readiness for school. Eventually vision becomes the dominate sense.
Accommodation is another component skill involving focusing the light entering the eyes.
This combined lens neuro-muscular system is a network integrating the eyes and the brain. Accommodation is developed rather well by age three and further accuracy is achieved throughout the early years of development. Additional skills are involved with teaming the two eyes together. Optometrists evaluate the development, function, and efficiency of these vision skills. This may have a negative impact on performance in school, the job, sports, and activities of daily living.