Lazy eye: signs and symptoms to watch for

Why lazy eye is hard to spot

With lazy eye, the brain relies on the better eye. The child usually sees well enough with both eyes open, so they do not complain. The National Eye Institute says lazy eye can be hard to notice [1]. The American Academy of Ophthalmology notes that children may not realise anything is wrong [16]. The NHS adds that many children have no noticeable symptoms [15].

Signs to watch for

The NHS and the National Eye Institute list these signs. Any one of them can have other causes, and none of them proves that a child has lazy eye [15][1]:

• Closing or covering one eye, or squinting.
• The eyes pointing in different directions.
• Poor depth perception.
• Tilting the head to look at things.
• Difficulty following a moving object with the eyes.
• Eye tiredness, frequent eye rubbing or headaches.
• Excessive blinking.

A visible eye turn

Strabismus is the one sign that you can see. One eye may drift inwards, outwards, up or down, sometimes only when the child is tired or unwell. The American Academy of Ophthalmology describes an eye turn as a visible sign of lazy eye risk [16]. The Task Force lists strabismus among the main risk factors for amblyopia [26]. If you see an eye turn, even an occasional one, book an eye test rather than waiting to see if it passes.

Everyday behaviour

Some signs show up in daily life rather than in the eyes themselves. The NHS lists difficulty catching or throwing a ball, and frequent tripping or bumping into things [15]. For older children, its page on children's eye tests also mentions reading difficulties, clumsiness and sitting close to screens [27]. These signs can have many causes, so treat them as a reason to check, not as a diagnosis.

When there are no signs

Because many children show nothing, checks are recommended even when everything seems fine. The US Preventive Services Task Force recommends vision screening at least once for all children aged 3 to 5 [26]. The National Eye Institute gives the same advice [1]. In the UK, the NHS advises seeing an optician if screening at school was not offered [27].

Extra attention is useful if a close relative had lazy eye, a squint or a strong glasses prescription, or if the child was born early. The Task Force lists family history and premature birth among the risk factors [26].

When to book a test

• You notice an eye that turns, or a head tilt or squint that keeps coming back.
• Your child complains of headaches, tired eyes or blurred vision.
• Your child has not had any eye check and is around 3 to 5 years old.
• A relative has had lazy eye or a squint.
• A school or nursery screening flagged a concern.

Also see a doctor promptly if the eyes look different or change suddenly, for example after an injury. This is general safety advice and it applies to any child.

In the UK, eye tests are free for children under 16, and for those under 19 in full-time education [27]. The earlier lazy eye is found, the more time there is for treatment. Our guide for parents explains what happens next.

What an eye test includes

The NHS describes several parts. The examiner checks the red reflex, which is the red glow from the back of the eye, and how the pupils react to light. Younger children may do picture or letter tests, and the tester checks for glasses needs with a refraction test [27]. In the US, the American Academy of Pediatrics advises instrument-based screening from about 12 months to 3 years, and direct testing of how clearly the child sees from around 4 years [28].

The test is short and does not hurt. If the result is not normal, your child will be referred to an eye specialist.