To understand how certain problems can affect your child's vision, it’s important
to know how normal vision happens. For children with normal vision, the following
things occur in this order:
Light enters the eye through the cornea. This is the clear, dome-shaped surface that
covers the front of the eye.
From the cornea, the light passes through the pupil. The amount of light passing through
is controlled by the iris. This is the colored part of your eye.
From there, the light then hits the lens. This is the clear structure inside the eye
that focuses light rays onto the retina.
Next, the light passes through the vitreous humor. This is the clear, jelly-like substance
that fills the center of the eye. It helps to keep the eye round in shape.
Finally, the light reaches the retina. This is the light-sensitive nerve layer that
lines the back of the eye. Here the image is inverted.
The optic nerve carries signals of light, dark, and colors to the brain’s visual cortex.
This part of the brain turns the signals into images (our vision).
The following are the most common refractive errors, all of which affect vision. Your
child may need corrective lenses for correction or improvement if they have any of
Refractive errors have been found to cluster in families. A variety of inheritance
patterns have been observed. These include dominant (one gene passed from a parent
with a refractive error to a child), recessive (caused by two genes, one inherited
from each parent who may or may not have a refractive error), and multifactorial (combination
of genes and environment). Refractive errors are present in a number of genetic disorders,
such as Marfan syndrome and Down syndrome.