Cataracts affect the eyes, causing visual problems. They usually affect older people, but some types can affect children. This article will explain why cataracts occur in children, and how to treat them.

What is a cataract?

Our eyes have developed with the ability to see objects far away, as well as things close to us. The eyes change focus quickly between these objects through the use of a lens, which is a clear disc-like structure that can be stretched and squashed to see objects near and far away.

In some individuals, this lens can become opacified. This means the clear lens will start to appear milky, which causes the vision through that lens to become blurred, out of focus or cloudy.¹ This is called a cataract.

Cataracts are usually associated with ageing and affect the elderly most commonly. However, there are certain conditions that can cause cataracts to form in infants and young children. This is rare, affecting only around 1 in 3000 children but where present carry an up to 15% chance of blindness.²

What are the types of cataracts commonly seen in children?

There are many different reasons why cataracts can arise in children, which can be broadly split into two groups.³

Congenital cataracts

This refers to cataracts that are present at birth, and arise when the baby is developing and growing within the womb. Usually these are caused by genetic issues. This can either be from inheriting mutated copies of genes from parents that predispose to cataracts, or from a random mutation occurring early on in the baby’s development. Certain infections acquired by the mother during her pregnancy can also cause cataracts development.

Secondary cataracts

These are cataracts that occur after birth and are the result of other conditions or come from an outside source. Examples can include long-term conditions that will eventually cause cataracts to form, exposure to certain medications such as long-term steroid use, injury to the eye/head and radiation exposure.

What are the causes of childhood cataracts?

There are many potential underlying reasons for a child developing a cataract.⁴

Genetic factors

For congenital cataracts, there is an abnormality with part of the genetic material of the child. This means the information the body needs to construct the eye lens is missing, which causes the cataract in the lens.

This occurs when there is a genetic mutation that is either inherited from parents, or that occurs at an early stage of development. A wide variety of gene mutations can be implicated in this.⁵

This can also be caused by errors in the numbers of chromosomes in a particular cell, as seen in conditions such as Down's syndrome and Edwards' syndrome.

Infections during pregnancy

Exposure to a particular range of infections, known as the TORCH group, can increase the chance of developmental problems in babies in the womb.⁶ One of these issues are congenital cataracts.

• Toxoplasmosis 
• Other –  including Varicella Zoster Virus (causing chickenpox in the young, shingles in elderly) 
• Rubella
• CMV – a viral infection with symptoms similar to the common cold, typically acquired from other young children at home
• Herpes – a sexually transmitted infection that can be transferred to the baby during vaginal birth

Injury

This can include direct blows or penetrating injuries to the eye, but also include blunt trauma to the head. Injury can also occur from a non-physical stimulus, such as exposure to radiation and laser photocoagulation.

Cataracts linked to other eye problems

A cataract in a child may indicate other underlying issues affecting the eyes, such as:⁷

• Microphthalmia
• Aniridia
• Peters’ anomaly
• Cat eye syndrome
• Long term eye inflammation (uveitis)

Cataracts linked to wider health problems

Many childhood cataracts are a symptom of an underlying disorder that can affect other parts of the body including:⁷

• Skin disorders such as progeria, ichthyosis and ectodermal dysplasia
• Heart disorders such as hypertrophic cardiomyopathy
• Neurological problems including Zellweger syndrome and Meckel-Gruber syndrome
• Bone and musculoskeletal disorders such as Smith-Lemli-Opitz syndrome, Marfan syndrome and Conradi-Hünermann syndrome
• Kidney disorders such as Lowe syndrome
• Dental disorders such as Cenani-Lenz syndrome
• Metabolic disorders such as galactosemia

Do cataracts in childhood affect both eyes?

In most cases, a single eye is affected. This is a unilateral cataract. The lens in the other eye is unaffected.

In some cases, both eyes may develop a cataract, known as bilateral cataracts. Slightly under a third of these cases are caused by hereditary diseases, with the remaining two thirds arising by chance (idiopathic). Very rarely, bilateral cataracts are caused by certain metabolic disorders or exposure to certain kinds of drugs.⁷

What are the signs that my child may have a childhood cataract?

You may notice that your child has:⁸

• Difficulty seeing or noticing nearby objects
• A cloudy white pupil
• Eyes looking in different directions or squinting
• ‘Wobbly’ eyes, or rapid eye movements
• Struggled to reach key developmental milestones due to visual problems

How are childhood cataracts diagnosed?

Many countries adopt a newborn screening assessment, where a baby is assessed shortly after birth. This checks for common developmental issues, and includes an examination of the red reflex of the eye. This is important as it can detect cataracts early, which means treatment starts sooner and the child is less likely to have consequences from adapting to the cataract.

If a childhood cataract is suspected, a thorough assessment can be performed, although the types of testing used depends on the maturity of the child and if they are able to speak. There will typically be some form of visual acuity assessment, and an examination of the deeper tissues of the eye by slit lamp examination. Eye movements are assessed, along with pressure in the eye (by tonometry), pupillary reactions and the blood vessels at the back of the eye.⁹

What treatment options are available for childhood cataracts?

The definitive treatment for cataracts is surgical removal of the affected lens. Non-surgical options are available, which are less invasive but have lower success rates.

Surgical options

There are generally two main methods of treating paediatric cataract:¹⁰

• Lensectomy - the entire lens of the eye containing the cataract is removed
• Lens aspiration - the soft jelly-like middle of the lens is gently sucked out. This is where the cataract forms, and so the cataract can be removed while the outer part of the lens (a more solid structure called the capsule) remains

The lens is the eye’s main method of focusing, and any procedure that removes part or all of the lens will affect the clarity of vision. Some surgeons may recommend inserting a replacement lens made of synthetic material to help compensate, which can be inserted at the time of cataract removal, or at a different point in the future. Supportive devices, such as contact lenses or glasses may also be recommended alongside this.¹⁰

The exact surgical technique can also vary depending on the age of the child at diagnosis. In particular, older children tend to have management options similar to the management of adult cataracts.

Be aware that surgery has risks; infection, glaucoma and secondary cataracts can all occur in the weeks to months following surgery. Your child should have regular follow up from your surgical team to ensure healing post operatively.¹⁰

Non-surgical options

These options will not resolve the cataract, but can help reduce some of the corrective side effects the eye may undertake to balance out the cataract, including amblyopia (lazy eye) and differences in visual acuity between the eyes.

Amblyopia therapy

This involves applying corrective patches over the child’s affected eye. It aims to correct a lazy eye that may have developed as the child’s eyes adapt to the cataract.⁷

Medication

• Atropine drops can be used to mildly blur vision in the eye with stronger vision. This stops one eye becoming dominant by diluting the pupil of the unaffected eye, balancing vision between both eyes⁷
• Phenylephrine can be used for correction of an overly dilated pupil, and is useful for cataracts where part of the lens remains clear, and therefore functional⁷

Other visual aids

Glasses and contact lenses address any residual issues with visual focussing after surgery. Children may need bifocal or multifocal glasses to help them adapt to near and far-sighted tasks.

Rehabilitation

After surgery, children will still need ongoing support to make up for the time spent with vision impaired by the cataract. It is important that they are followed up regularly, to assess for any potential complications just after the surgery, and to ensure that their vision remains unaffected.

Developmental and educational support is also recommended to help with visual skills development and to allow these children to adapt to activities of daily life.

Parents will also benefit from educational support, to better understand the condition, as well as with technical activities such as how to administer eye drops and understanding when the child may be suffering from a complication. Counseling and support groups are available to both children and wider families if needed.¹¹

Summary

Cataracts are a rare condition to find in children, but when present they account for a significant proportion of childhood visual impairment. These develop for many reasons, ranging from developmental conditions to secondary causes. The earlier the cataract is identified and treated, the more positive the outcome.