Lazy eye (amblyopia) in children: the signs, and why treating it early matters

What a lazy eye is

Amblyopia means one eye sees less clearly than the other, even with the right glasses, because the connection between that eye and the brain did not develop fully in early childhood. The brain learns to favour the stronger eye. It is not the same as a squint, although a squint is one of the things that can cause it.

What causes it

• One eye needing a much stronger prescription than the other. This is the most easily missed, because the eyes look completely normal.
• A squint, where one eye turns in, out, up or down. Squinting or sitting close to the TV.
• Less often, something blocking the view, such as a droopy eyelid or a cloudy lens.

The signs

Often there are none. A child with one good eye manages well and rarely complains. You might notice an eye turning, head tilting, covering one eye, or bumping into things on one side, but many lazy eyes are only found at an eye test.

Why early matters

Treatment works best while a child’s vision is still developing, so the younger it is found, the better the result. That is why we suggest a first eye test from about age three, rather than waiting for school.

How it is treated

Usually with glasses first, to give the weaker eye a clear picture. If that is not enough, the stronger eye is covered for part of the day with a patch, or blurred with eye drops, so the weaker eye has to work. Children who need patching or drops are referred to the hospital eye team, and we look after their glasses.

Your next step

Children’s eye tests are free on the NHS for under-16s, from age three. Children’s eye tests.

The short version

• A lazy eye has not developed full sight, so the brain favours the other eye
• Often there are no signs; it is found at an eye test
• Treatment works best while children are young
• Glasses first, then patching or drops if needed
• Free NHS eye tests for under-16s, from age three

Book a child’s eye test