A lazy eye (amblyopia) is caused when something disrupts the normal development of vision.
It's often assumed that younger children have the same vision as adults, but this isn't the case.
Children have to learn how to see more specifically, their brains have to learn how to interpret the nerve signals sent from the eyes to the brain.
It usually takes around three to five years before children can see as clearly as adults, and up to seven years before the eyes become fully developed.
If something affects one of the eyes as it develops,the signals become disrupted, which affects the quality of the images interpreted by the brain.
The brain starts to ignore thepoor-quality images and becomes increasingly reliant on the stronger eye.
Commonconditions that disrupt the development of vision and can cause lazy eye are discussed below.
Asquint is a common eye condition that affects around 1 in 20 children.If a child has a squint, one eye looks straight ahead but the other eye looks off to the left, right, up ordown.
This causes the brain to receive two very different images that it can't combine. In adults, this would result indouble vision.
In children who are still developing, it causes the brain to ignore images from the squinting eye, leading to a lazy eye.
Some babies are born with squints. Older children can develop a squint as a result of a group of eye conditions called refractive errors.
Refractive errors are caused when the light rays entering the eye aren't properly focused. This is caused by problems with the structure of the eye.
Two examples of refractive errors that could lead to a lazy eye are:
Refractive errors can cause thebrain to rely on the signals from one eye, meaning the other eye fails to develop properly.
Less common conditions that can cause a lazy eye include:
Find out what a lazy eye (amblyopia) is, what causes it and how it's diagnosed and treated.
Find out how a child's vision develops and how lazy eye is caused when something, such as a squint or refractive error, disrupts normal development.
Read about the routine eye tests that your baby will have and at what ages. It's important for a lazy eye (amblyopia) to be diagnosed and treated as early as possible.