Symptoms of childhood cataracts can vary depending on how cloudy the lens is, where the cloudiness is in the lens, and whether 1 or both eyes are affected.

When your child is very young, it can be difficult to spot signs of cataracts.

But your baby's eyes will be routinely examined within 72 hours of birth and again when they're 6 to 8 weeks old as part of the Healthy Child Programme.

Sometimes cataracts can develop in children after these screening tests.

Signs that your child may have developed cataracts can include:

• poor vision – you may notice your child has difficulty recognising and following objects or people with their eyes
• rapid uncontrolled eye movements or "wobbling" eyes – known as nystagmus
• the eyes pointing in different directions – known as a squint
• a white or grey pupil – this can also be a sign of other serious conditions, such as retinoblastoma, and should be checked by a doctor immediately 

Your child may also find it difficult to see clearly in bright light or if there's any glare.

When to seek medical advice

Visit your GP or tell your health visitor if you have any concerns about your child's eyesight at any stage.

Your GP will examine your child's eyes and can refer them to an eye specialist for further tests and treatment if necessary.

Read about diagnosing childhood cataracts.

There are a number of reasons why a child may be born with cataracts or develop them while they're still young.

But in many cases it's not possible to determine the exact cause.

Some of the main causes of childhood cataracts are described below.

Genes and genetic conditions

Cataracts present from birth (congenital cataracts) are sometimes caused by a faulty gene being passed to a child from their parents.

This fault means that the lens doesn't develop properly.

It's estimated there's a family history of congenital cataracts in around 1 in every 5 cases of the condition.

Recent research suggests genetic causes are responsible for the majority of bilateral congenital cataracts in the UK.

Cataracts can also be associated with conditions caused by chromosome abnormalities, such as Down's syndrome.

Chromosomes are the parts of the body's cells that carry the genes.

Infections during pregnancy

Congenital cataracts can also be caused by infections caught by the mother during pregnancy.

The main infections linked to an increased risk of congenital cataracts include:

• rubella (german measles) – a viral infection that can cause a red-pink spotty skin rash
• toxoplasmosis – a parasitic infection caught by consuming food, water or soil contaminated with infected cat's faeces
• cytomegalovirus (CMV) – a common virus that can cause flu-like symptoms
• chickenpox – a mild but highly infectious condition caused by the varicella-zoster virus 
• herpes simplex virus – a virus that often causes cold sores

Causes of acquired cataracts

Cataracts that develop in children after they're born are known as acquired, infantile or juvenile cataracts.

Causes of this type of cataracts can include:

• galactosaemia – where the sugar galactose (which mainly comes from lactose, the sugar in milk) can't be broken down by the body 
• diabetes – a lifelong condition that causes a person's blood sugar level to become too high
• eye trauma – as a result of an injury to the eye or eye surgery
• toxocariasis – a rare parasitic infection that can sometimes infect the eyes, spread from animals to humans via their infected faeces

But most of these problems are either rare or don't usually cause cataracts to develop in children.

It's important childhood cataracts are diagnosed as early as possible. Early treatment can significantly reduce the risk of long-term vision problems.

Newborn screening

All parents are offered a physical examination for their baby within 72 hours of birth and again when their baby is 6 to 8 weeks old.

Childhood cataracts are among the conditions screened for during the newborn physical examination.

Your baby's eyes are checked by looking at their general appearance and how they move.

If your baby's eye looks cloudy, it could be a sign they have cataracts.

An important part of the check is looking for the "red reflex" using a bright light.

The red reflex is a reflection from the back of the eye that's similar to the red eye effect sometimes seen in flash photography.

If no red reflex, or a weak one, is seen, it may mean there's cloudiness in the lens.

Vision tests for older babies and children

Although cataracts can be present from birth (congenital), they sometimes don't develop until a child is older. 

Visit your GP or tell your health visitor if you have any concerns about your child's eyesight at any stage.

You should also make sure your child has routine eye tests to check for any problems with their vision.

All children under the age of 16 are entitled to free sight tests, which they should have about every 2 years.

Read more about eye tests for children and NHS eye care services.

Referral to a specialist

If it's thought your baby or child may have cataracts, they'll usually be referred to hospital to see an ophthalmologist as soon as possible. 

An ophthalmologist is a doctor who specialises in eye conditions and their treatment.

Before the ophthalmologist examines your baby, they'll apply drops to their eyes to dilate (widen) their pupils.

Although the drops will sting, they won't damage your baby's eyes and the effect will wear off after a few hours.

The ophthalmologist will examine your baby's eyes using medical instruments that have a light at one end and produce a magnified image of the eye.

Bright light is shone into your child's eyes, enabling the ophthalmologist to look inside them.

They'll diagnose cataracts if they can see them in the lens.

If your child is diagnosed with cataracts, the ophthalmologist will discuss the treatment options with you.

Whether or not your child needs cataract surgery will largely depend on whether their vision is affected.

If cataracts aren't causing any problems, immediate treatment may not be necessary.

Instead, your child may only need regular check-ups to monitor their vision.

If your child's vision is affected by cataracts, they'll usually need to have surgery to remove the cloudy lens (or lenses) followed by the long-term use of glasses or contact lenses.

As childhood cataracts are rare, it's difficult to predict how much a child's vision will be improved by treatment.

Many children are likely to have reduced vision in the affected eye (or eyes) even with treatment, although most will be able to go to mainstream schools and live full lives.

Cataract surgery

Cataract surgery for babies and children will take place in hospital under general anaesthetic, which means your child will be unconscious during the operation.

The operation, which usually takes between 1 and 2 hours, will be carried out by an ophthalmologist, a doctor specialising in the treatment of eye conditions.

If the cataracts are present from birth, the operation will be carried out as soon as possible, usually 1 to 2 months after your baby is born.

Before the operation, the ophthalmologist will apply drops to the eye to widen (dilate) the pupil.

A very small cut is made in the surface (cornea) at the front of the eye and the cloudy lens is removed.

In some cases, a clear plastic lens called an intraocular lens (IOL) or intraocular implant will be inserted during the operation to replace the lens that's removed. This is because the eye can't focus without a lens.

But it's more common in babies and young children for external contact lenses or glasses (if both eyes are affected) to be used to compensate for the removal of the lens.

These will be fitted a week or two after the operation. 

Most ophthalmologists recommend using contact lenses or glasses in children under 12 months old at the time of surgery.

This is because there's a higher risk of complications and further surgery being needed in babies who have an IOL inserted.

When the operation is complete, the incision in your child's eye will usually be closed with stitches that gradually dissolve.

After the operation

After the operation, a pad or transparent shield will be placed over your child's eye to protect it.

Most children will need to stay in hospital overnight so their recovery can be monitored.

If your child has cataracts in both eyes (bilateral cataracts), the ophthalmologist will usually operate on each eye separately to reduce the risk of complications affecting both eyes.

You and your child will be able to go home between operations. The second operation will usually take place within a week of the first.

You'll be given eyedrops to give to your child at home. The drops help reduce swelling and redness (inflammation) in the eye.

You'll need to put them into your child's eye every 2 to 4 hours. You'll be shown how to do this before you leave hospital.

See risks of childhood cataract surgery for more information about the problems that could develop after your child's operation.

Further treatment

Most children will need to wear glasses or contact lenses after having cataract surgery.

This is because the vision in the treated eye or eyes will be blurred, as they're no longer able to focus properly on their own.

Replacing the focusing power of the cataract lens is as important as the surgery to remove it.

Glasses or contact lenses will also usually be needed if an artificial lens has been fitted to allow your child to focus on closer objects.

This is because artificial lenses can usually only focus on distant objects.

The glasses or contact lenses will often be fitted a few weeks after the operation, usually by an eye specialist called an optometrist.

They'll advise you about how often contact lenses should be replaced (usually every day) and teach you how to do this.

Your child will continue to have regular check-ups after surgery so their vision can be monitored.

As your child's vision develops with age, the strength of their contact lenses or glasses can be adjusted.

Wearing a patch

For almost all cases of unilateral cataract (where 1 eye is affected) and if a child with bilateral cataracts has weaker vision in 1 eye, the optometrist may recommend they wear a temporary patch over their stronger eye. This is known as occlusion therapy.

Occlusion therapy aims to improve vision in the weaker eye by forcing the brain to recognise the visual signals from that eye, which it may have been ignoring previously. 

Without treatment, most children with unilateral cataract won't be able to develop good vision in their operated eye.

Orthoptists are hospital-based specialists who are often described as physiotherapists for the eye. They assess visual function.

Your orthoptist will tell you when your child should wear the patch and how long they may need it for.

This will depend on the type of cataract your child had and how weak their vision is.

Wearing a patch can be an unpleasant experience for your child and they'll need lots of encouragement to keep it on.

Cataract surgery is usually very successful, but some children may experience complications and need further treatment.

Even if a child's cataracts are successfully removed during surgery, their vision may still be affected by other eye conditions.

For example, lazy eye can occur if there's weaker vision in 1 eye.

The brain ignores the visual signals coming from the weaker eye, which leads to the vision in the affected eye not developing properly.

Lazy eye will need further treatment, usually wearing a patch over the stronger eye, although it may not always be possible to fully correct the problem.

Cloudy vision

If your child has an artificial lens fitted during cataract surgery, the main risk is a condition called posterior capsule opacification (PCO).

This is where part of the lens capsule (the "pocket" that the lens sits inside) thickens and causes cloudy vision.

This isn't the cataract returning, but is caused by cells growing over the artificial lens.

PCO is common after cataract surgery where an artificial lens is implanted, and it usually develops within 4 to 12 months of having the operation.

If your child develops PCO, they may need another operation to correct it.

Laser eye surgery, where energy beams cut through part of the eye, may be used.

During the procedure, the cloudy part of the lens capsule will be removed, with enough left to continue holding the artificial lens in place.

The procedure should only take around 15 minutes, and vision should be improved immediately or within a few days.

As no surgical incisions or stitches are necessary, your child can usually return to their normal activities straight away.

The Royal National Institute of Blind People (RNIB) website has more information about laser treatment for posterior capsule opacification (PCO).

Other complications

Other complications that can occur after an operation to remove childhood cataracts include:

Glaucoma

Glaucoma is where vision is affected by increased pressure inside the eye.

Without successful treatment, glaucoma can cause irreversible damage to key structures in the eye and blindness.

It's a lifelong risk for children who have cataract surgery, so these children will need their eye pressure measured at least once a year by an optician for the rest of their lives.

Squint

A squint is where the eyes look in different directions.

Pupil abnormalities

This can include the pupil becoming a more oval shape. This is common and doesn't usually affect vision.

Retinal detachment

Retinal detachment is where vision is affected by the retina (the layer of light-sensitive cells that line the back of the eye) becoming separated from the inner wall of the eye.

Cystoid macular oedema

This is where fluid builds up between layers of the retina, sometimes affecting vision.

Infection

This can include endophthalmitis, a rare bacterial infection.

In many cases, medication or further surgery will be required to treat these problems if they develop.

When to seek medical advice

You should immediately contact the hospital where the operation was carried out if your child has:

• any signs of pain
• bleeding
• a lot of stickiness or redness in or around their eye