Everything you need to know about lazy eye, a childhood disorder in which one eye doesn’t develop fully, so the vision becomes reduced.
Lazy eye, medically known as amblyopia, is one of the most common childhood eye conditions, affecting about one in 25 children. Amblyopia occurs when the brain favours one eye (and ignores signals from the other ‘lazy’ eye) due to vision problems. Left untreated lazy eye can lead to permanent vision impairment. The NHS provides routine eye checks for children so any concerns will likely be spotted, but if you are worried it is worth speaking to a medical professional.
To help you get started, family GP Dr Lara Batchat looks at lazy eye symptoms, causes, treatment and prevention tips:
What is lazy eye?
Lazy eye is a childhood disorder in which one eye doesn’t develop fully, so the vision becomes reduced. Anything that affects the eye in early childhood means that the eye doesn’t get used properly, stunting its development and resulting in amblyopia. The eye would normally develop with age, finally ‘graduating’ at about 7-8 years old, and so if it doesn’t have the opportunity to grow and form pathways with the brain by then, it will be affected permanently.
If one eye is affected in any way (for example due to a squint or a cataract), creating a ‘good’ eye and ‘bad’ eye scenario, the brain receives mixed messages containing different sets of images, which becomes confusing. It’s easier for the brain to process one clear image rather than two that are mismatched, and so the image from the ‘good’ eye will take priority, while that of the ‘bad’ one gets ignored. No-one likes to feel ignored, and so in the same way that a friend might shy away from a person who continually disregards them, so the affected eye can feel equally as insulted! It becomes lazy, avoiding the work of vision and so failing to develop as it usually would.
Anything that affects the eye in early childhood means that the eye doesn’t get used properly, stunting development and resulting in amblyopia.
The result is that eyesight from that eye is reduced, not just because of the original condition affecting that eye, but also due to the lack of development – the amblyopia. This is why any condition affecting the eye in early life should be dealt with as soon as possible, so there’s time for the eye to learn how to do its job.
Lazy eye symptoms
Amblyopia causes reduced vision in one (or sometimes both) eyes, but often doesn’t cause symptoms so it can be tricky to spot. Younger children may be unable to explain what’s wrong, so look out for the following lazy eye signs and symptoms:
- You may notice your child struggling to pick up small objects, such as raisins or toys.
- Their eyes may stop pointing in the same direction.
- Your child may be unusually clumsy.
- They may have difficulties reading (holding the book too close to the face or losing the place regularly).
- They may start sitting too close to the TV.
- Older children may complain of headachesor eye strain.
However, lazy eye often goes completely unnoticed. If amblyopia goes untreated there will be a permanent reduction in eyesight in that eye, so if you have any concerns whatsoever make an appointment with your GP or optometrist.
Lazy eye complications
Amblyopia affects both the field of vision and the way the eye processes three dimensional images. In the former, because the images from one eye are effectively ignored, either the right or left side of view may be cut short.
With regards to three dimensional vision, there is a reduction in the understanding of depth – so if your child is given tasks that require hand-eye coordination such as threading a needle or throwing a ball to another person, they might struggle.
Lazy eye causes and risk factors
There are several common culprits of lazy eye, including the following:
A squint is a condition where the eyes don’t point in the same direction, and is a common cause. It usually affects one eye, which may drift up, down, right or left. This might happen all the time or just occasionally and can be particularly noticeable when your child is tired. Because the brain receives one good, clear image from the focussed eye, and a poorer image from the affected eye, this eye becomes lazy and amblyopia develops.
🔹 Refractive errors
Refractive errors (often referred to as long or short sightedness, or astigmatism) are another common cause of amblyopia and means the lens of the eye can’t focus images clearly. Usually, refractive errors will be roughly equal in each eye, but occasionally the errors are significantly different – this is known as anisometropia. This is another circumstance where the brain finds itself in a position of being given two different pictures which are mismatched, and so the poorer quality one will be ignored, and lazy eye will develop.
🔹 Stimulus deprivation amblyopia
Any disorder that prevents good vision in the eye during the early years can result in a lack of development of the connections between the eye and the brain and this is termed stimulus deprivation amblyopia. A cataract (cloudy eye lens), scarring of the cornea (the surface of the eye) or droopy eyelid can all cause this, so it’s really important to treat any eye related condition early in young children.
Amblyopia is also more likely to develop if someone else in the family has had it, or if your child was born early or with a very low birthweight.
Lazy eye diagnosis
If you have any concern surrounding your child’s vision, it’s important to see your GP or optometrist. They will usually refer you to an orthoptist (a specialist in eye movement disorders) who can diagnose amblyopia using special visual tests. These tests will differ according to age, enabling diagnosis in even very young children who can’t read or speak.
Eye tests for children
Amblyopia is often not apparent to parents, which is why there are several points in a child’s life at which the NHS provides routine eye checks:
- Newborn: within 72 hours of birth and at the GP 6-week baby check, the eyes will be examined for any physical problems.
- 1-2 years old: at around 1 year, or between 2 – 2 ½ of age, there is a development review at which any concerns with vision can be raised, and an eye test arranged if necessary.
- 4-5 years old: after school has started, all children should have an eye test. Sometimes these are done on school premises, but if not, book a free eye test at a local optician.
Lazy eye treatment
Treatment for amblyopia involves correcting the underlying cause and then training the eye to start working again. The earlier treatment is started, the more likely it is to be successful – treatment before the age of 6-7 years can usually correct the vision fully, however if left beyond this age there is likely to be permanent visual loss.
Glasses will usually be prescribed for those with refractive errors and cataracts and squints may be treated surgically.
Treating the lazy eye is usually done by restricting the use of the good eye, so that the lazy eye can be retrained, medics call this ‘occlusion’. This is usually done by patching the good eye for several hours each day with a soft, comfortable patch with sticky edges. The length of treatment depends on the age of your child and the degree of amblyopia. Follow-up appointments are normally every three months at first, and your child should be monitored until they are eight years old, when the eye is fully developed.
Sometimes children find patch wearing difficult or embarrassing, in which case eyedrops can be used instead to blur the vision in the good eye, forcing the lazy eye to work. These drops contain a medicine called atropine. Unlike a patch which your child can tear off, once in the eye the drops can’t be removed.
✔️ Vision correcting glasses
Another option is wearing glasses that blur or obstruct the vision in the good eye, for the same reason. Regardless of which method of occlusion is used, it is of course vital that the good eye has regular breaks and is enabled to see at regular intervals, so that it, too, does not develop amblyopia.
✔️ Vision therapy
While the good eye is occluded it’s important to work the lazy eye effectively, this is known as vision therapy. Getting the child to do tasks such as colouring in or other close-up activities and playing visually demanding games gives the eye a real opportunity to build up its connections with the brain and get it working again.