Children do not usually complain about their sight, but may show signs of not being able to see properly.
Things to look out for include:
Sitting close to the TV
Holding objects very close to their face
Blinking a lot
One eye turning in or out.
Children young as 6 months can have an eyes tested because they should be able to see as well as adults in terms of focusing ability, color vision and depth perception. To assess whether your baby’s eyes are developing normally, the doctor typically will use the following tests:
Evaluate whether the eye’s pupil opens and closes properly in the presence or absence of light.
Testing determines whether your baby’s eyes are able to fixate on and follow an object such as a light as it moves. Infants should be able to fixate on an object soon after birth and follow an object by the time they are 3 months old.
Involves using cards that are blank on one side with stripes on the other side to attract the gaze of an infant to the stripes. In this way, vision capabilities can be assessed without the use of a typical eye chart.
Source: All About Vision