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What is Lazy Eye?

The medical term for lazy eye is Amblyopia, a condition where the vision in one eye is significantly less effective compared to the other because the eye-to-brain pathways have not developed properly. This leads to the brain essentially ignoring the information from the affected eye. Usually beginning in early childhood, between the ages of one and seven years old, an estimated one in fifty children will develop some degree of amblyopia. Left untreated, it can seriously affect an individual throughout their entire life.

Causes of lazy eye

Amblyopia specifically refers to when the eye and brain connections have not developed correctly. It can have several different causes:

Refractive errors: Refractive errors are where the shape of the eye prevents light from focussing on the correct part of the retina, resulting in blurred vision. A common cause for amblyopia, these types of problems include astigmatism, being long-sighted (hyperopia) or being short-sighted (myopia).  

Where these errors have developed unequally, the brain may rely more on information from the eye which sees more clearly, effectively ignoring the eye with more blurred vision.  Over time, the ‘ignored’ eye will become weaker and lazier.

Strabismus (squint): Another common cause of lazy eye is a squint, where the eyes generally look in different directions, instead of both eyes working together and looking straight ahead. Commonly it affects one eye, although it can affect both. It is often due to the muscles around the eye not working together as they should.

Because of the misalignment, the child’s vision does not line up and they may see two different pictures, or double vision. To process the visual information better, the brain will shut out the signals from the deviating eye which then becomes weaker.

Deprivation amblyopia: This occurs when one eye has been deprived of vision by a physical blockage or anomaly. This type of amblyopia includes congenital childhood cataracts, scars on the surface of the eye, a droopy eyelid and other rarer disorders. If the child is unable to see properly with one or both eyes for these reasons, the brain cannot build the right connections with the affected eye.

Symptoms & diagnosis

Sometimes a child’s eyes may look different but there are often no outward signs of amblyopia, or many of the conditions that cause it. Any noticeable squint, head tilting, putting their face very close to books and TV screens, complaining of headaches, poor hand-eye coordination for their developmental stage or rubbing their eyes a lot could all indicate possible eyesight problems.

Any concerns about a child’s eyesight can be discussed with health visitors and GP’s, but can only be thoroughly tested by a qualified optometrist who will be able to either diagnose or refer the child onto hospital based eye specialists for further investigation. Appointments can be arranged with almost any high street opticians and both tests and treatment are free for under sixteens (under nineteen years old if the child remains in full-time education).

It is a common misconception that toddlers are too young to have their eyes tested or that a child needs to be able to read to have one. Many people also mistakenly believe that you should only get your child tested if you notice a problem. All high street opticians are trained to test children, even toddlers and babies. Some optician practices may even specialise in certain areas, such as children with learning difficulties.

The Association of British Dispensing Opticians (ABDO) recommends that children are given their first eye test as a toddler, well before they start school. The earlier a child is diagnosed, the better their chances of overcoming the problem are.


Treatment will vary depending on the individual child. Any underlying or contributory issues need to be addressed first. For refractive errors and some squints, this may be with prescription glasses to correct the vision balance. For some other problems, such as cataracts, surgery may be required.

Once these problems have been corrected, then the child may be given patches to wear over the stronger eye to build up the vision in the weaker eye and its brain connections. An alternative to patches is special eye drops to blur the vision in the stronger eye.

Not all children will happily tolerate eye patches or drops so discuss any difficulties, as soon as they occur, with the eye specialist looking after your child.

Treating amblyopia and building the eye to brain connections will take a long time and all treatment advice needs to be followed exactly for the best chance of success.

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