Congenital cataract: for patients

• Overview
• The condition
• Treatment
• Current research
• Practical advice
• Referral to a specialist centre
• Further information and support
• A patient’s perspective
• References
• Congenital cataract: for professionals

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Overview

The lens of the eye is usually transparent and is responsible for focusing incoming light onto the macula, making our vision clear and sharp. Cataract occurs when the lens becomes cloudy and result in blurry or misty vision. It usually develops in older people (age-related cataract) but very rarely, some babies are born with this condition. This is known as congenital cataract and it can develop in one (unilateral) or both (bilateral) eyes. Approximately 3-4 per 10,000 babies are affected and it can profoundly impede normal visual development if not treated early or left untreated, resulting in permanently reduced vision (developing a “lazy eye”). Depending on the cataract’s impact on visual development, close monitoring may be sufficient in milder cases, while surgery to remove the cataract is usually required in severe cases.

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The condition

Symptoms

1) Abnormal visual behaviour

The following features may alert parents and healthcare workers that a congenital cataract may be present:

• A white coloured pupil (there are other serious causes of a “white pupil” as well which will need urgent medical attention)
• Rapid, involuntary movement of the eyes (known as nystagmus)
• Strabismus/squint (abnormal alignment of the eyes when looking at an object or appearing “crossed eye”)
• The child may not be responding to visual stimuli such as lights, faces or toys

2) Amblyopia (“lazy eye”)

The visual impact of congenital cataracts is significantly different from adult cataracts as it can have a long-term effect on a child’s visual development if not treated early or left untreated.

When a baby is born, their eyes and brain work together to build a visual pathway that allows the brain to process visual information collected from the eyes. Most of this pathway develops up to the age of 8 years though further changes can be observed into adulthood.^[1] The most crucial period of this development is between the first two to four months of life. For the visual pathway to develop normally, the eyes need to constantly send clear images to stimulate the brain.

Congenital cataracts may hinder this development as the brain chooses to ignore the blurry images from the affected eye in favour of the clear images sent from the unaffected eye. As a result, the visual pathway in the affected eye is not properly developed, leading to a condition called amblyopia or “lazy eye”. Vision in the “lazy eye” may be permanently reduced if not detected and treated in time. Children affected by bilateral cataracts may develop amblyopia in both eyes.

However, not all cataracts will affect vision. A cataract located more centrally within the lens will have more impact on vision than one that is located near the edge of the lens, and therefore does not impede incoming light as much.

3) Other eye conditions

Some children with congenital cataracts may also be affected by other eye conditions as well, which include:

• Malformations of the structures at the front of the eye such as the cornea, iris and/or trabecular meshwork (collectively termed anterior segment dysgenesis)
• Microphthalmia, anophthalmia and coloboma (MAC)
• Glaucoma
• Abnormal development of the vitreous or retina (vitreoretinal dysplasia)

4) Medical conditions affecting other parts of the body

Congenital cataract is usually an isolated eye condition but in a minority of children, it may be part of a wider systemic condition which require input from paediatricians and other relevant specialists as well.

Cause

Almost 90% of bilateral cataracts are due to genetic changes while this is less common in unilateral cataracts. In fact, most unilateral cases have no identified cause (idiopathic) and are not related to other medical conditions.^[2-5]

Currently, 115 genes have been identified to cause congenital cataracts and mutations in any one of these genes may present in two ways:

• Syndromic – The cataract is linked with other health conditions
• Non-syndromic – Cataract with/without other eye conditions

There are also non-genetic causes which can lead to either unilateral or bilateral cataracts in children:

• Maternal infections during pregnancy (Toxoplasma, syphilis, varicella zoster virus, parvovirus B19, coxsackievirus, rubella, cytomegalovirus and the herpes simplex virus)
• Chronic eye inflammation due to a condition that causes joint inflammations in children called juvenile idiopathic arthritis (JIA)
• Previous physical injury to the eye
• Medical interventions such as long-term usage of steroids or radiotherapy (such causes are relatively rare in this age group)

How is it diagnosed?

All babies in the UK are screened for eye and other physical problems in the first 72 hours after birth as part of the newborn screening programme. Babies are then checked again between 6 and 8 weeks of age. Congenital cataracts are usually detected during these examinations and babies are referred to an ophthalmologist for further assessment.

During the clinic appointment, eye drops that dilate the pupils are applied so that the ophthalmologist can see the cataract clearer and also examine the heath of the retina and optic disc. In cases where a genetic cause is suspected (such as bilateral cataracts), it can be helpful for the ophthalmologist to examine the parents as well even though they may be unaware of any visual problems. This is because either parent may have a very mild cataract which does not affect his/her vision.

Genetic testing can be undertaken to help identify the causative gene so that families can have a more informed genetic counselling session.

If there is evidence suggesting other parts of the body may be affected, the child will be referred to a paediatrician for further evaluation which may include:

• General physical examination
• Developmental assessment
• Blood tests
• MRI (magnetic resonance imaging) of the brain
• Ultrasound scans of the heart and kidneys

This is not an exhaustive list and other tests may be requested depending on the examination findings.

How is it inherited?

The genetic changes causing congenital cataracts is usually inherited in an autosomal dominant manner (44% of cases).^[2] This means that only one copy of the faulty gene (inherited from either parent) is required to cause disease. As a result, each newborn of the affected individual has a 50% chance of inheriting the condition regardless of gender.

Less commonly, genetic changes causing congenital cataract can also be inherited in the following patterns:

• Autosomal recessive
• X-linked recessive
• X-linked dominant

If your child is affected by cataracts that may be due to a genetic cause, it is advisable to see a genetic counsellor to obtain more information and advice on inheritance and family planning options.

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Treatment

Is there any treatment?

The treatment for congenital cataracts is a long process which require significant parental effort and dedication. It involves a combination of the following:

• Surgery to remove the cataract (cataract surgery) with or without a clear artificial lens implant, also known as an intraocular lens (IOL)
• Regular monitoring of vision after surgery or if surgery is not undertaken
• Patching of the stronger eye so that visual development of the weaker eye can be stimulated (occlusion therapy)
• Contact lenses/glasses

Does my child require surgery?

If the cataract is not impeding visual development, then surgery is not required. Regular monitoring of vision to make sure it is not getting worse is usually sufficient. Occasionally, occlusion therapy may be required if the affected eye is becoming weaker but not severe enough for surgery.

Cataract surgery is recommended if vision is significantly affected. If the cataract is present from birth, surgery is usually done between 6-8 weeks of age as there is a higher risk of complications if performed earlier.^[6-8] The procedure is done under general anaesthesia, which means the child will be unconscious during the operation. For children with bilateral cataracts, surgery is performed one eye at a time.

Once the natural lens (which is affected by cataract) has been removed, the eye loses its focussing power. To address this, two options are available:

• Implanting an IOL during surgery
• Leaving the eye without a lens (aphakia) and using contact lenses or glasses to help with focussing  

Multiple factors need to be considered when deciding between the two options and the ophthalmologist looking after your child will discuss with you the possible risks and benefits of each option and the surgery itself.

Generally, children younger than 2 years of age are left aphakic as IOL implantation in this age group is associated with higher risk of complications with no additional benefits to visual improvement.^[8-11] A subsequent surgery can be performed to insert an IOL implant at a later age in aphakic children.

What are the possible complications after surgery?

The following complications may occur after surgery:

• Visual axis opacification—This is a very common complication associated with cataract surgery in children. It occurs when the remaining lens cells start to collect and form a membrane over the lens capsule (the “pocket” that the natural lens sits in). As a result, vision may become blurry again as less light is able to pass through. Further surgery may be required if vision is significantly affected. The risk is higher in children under 2 years of age implanted with an IOL
• Glaucoma—Children who have had congenital cataract surgery are at risk of developing this condition; long-term monitoring is required
• Unable to focus on near objects such as a book (accommodation)—The natural lens has the ability to adjust its shape to focus clearly on near and far objects. This ability is lost when the natural lens is removed. Even if an IOL is implanted, the child may still require contact lenses/glasses to help focus on near objects as the implanted IOL can only focus on distant objects
• Detachment of the retina
• Eye infection (rare)  

Visual rehabilitation after surgery

Cataract surgery itself does not guarantee visual improvement. Multiple steps are taken to maximise visual pathway development in the operated eye in order to achieve the best possible long-term outcome. These usually include:

• Regular monitoring of visual function and other associated eye conditions such as glaucoma which will require treatment
• Updating the contact lens/glasses prescription as required—This may be fairly frequent initially as the child’s eye is still developing but usually stabilise when older
• Occlusion therapy—The stronger eye is usually patched for several hours every day so that the weaker eye can be stimulated. This is usually a lengthy and demanding process of both the child and parents. Some children may need consistent encouragement but strict compliance increases the likelihood of achieving a better visual outcome in the long-term

The level of visual improvement varies among patients and depends on multiple factors, which include:

• Timing of the cataract being detected (i.e. earlier detection results in earlier treatment)
• If there are other concurrent eye and/or medical conditions
• Any complications during or after surgery
• Compliance to occlusion therapy

Children with bilateral cataracts that are operated tend to have better vision compared to those affected by unilateral cataracts. However, vision in the operated eye(s) is still usually reduced despite rehabilitation measures with only a quarter or less achieving the minimum driving standards in the UK.^[7,8,11,12]

Systemic management

Children affected by syndromic cataracts tend to be complex and hence a multidisciplinary approach involving various specialists are recommended. Paediatricians can help co-ordinate the various specialities involved and establish appropriate care pathways including support in the community.

Visual impairment at a young age can also have a negative impact on a child’s early general development. Therefore, timely referral to practitioners familiar with developmental surveillance and intervention for children with visual impairment (VI), such as developmental paediatricians as well as a Qualified Teacher of children and young people with Visual Impairment (QTVI) is crucial to optimise their developmental potential.

The Developmental Journal for babies and young children with visual impairment (DJVI) is a structured early intervention programme designed to track developmental and vision progress from birth to three years of age. It is mainly used by qualified healthcare professionals working in services providing support to babies and young children with VI in conjunction with the child’s parents. Children with VI may be referred to specialist services such as the developmental vision clinic in the Great Ormond Street Hospital for Children or other specialist developmental services for further management.

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Current research in congenital cataracts

Most of the current clinical trials are focussed on exploring different surgical techniques and intraocular lenses to help patients achieve the best possible visual outcomes whilst minimising development of complications after surgery.

Work is also being done to improve the diagnosis of congenital cataracts caused by genetic changes through the incorporation of genomic medicine into clinical practice and expanding genetic testing services in the UK. This will invariably help researchers to identify other genes that are associated with lens development where harmful mutations may lead to formation of congenital cataracts.

Related links

• Research Opportunities at Moorfields Eye Hospital UK
• Searching for current clinical research or trials

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Practical advice

Living with congenital cataracts

The visual function of patients is highly variable but majority still have some degree of reduced vision despite surgery and rehabilitation measures. However, they are still able to lead a relatively independent life through maximising their available vision and having access to social support. Here are some ideas:

• Attending the low vision clinic which provides access to low vision specialists, Eye Clinic Liaison Officers (ECLOs) and visual aids
• Utilising assistive technologies that can improve quality of life
• Getting in touch with the local education authority for access to qualified teachers for children with visual impairment (QTVI) and special educational needs co-ordinator (SENCO)
• Registering as sight impaired (SI) or severely sight impaired (SSI) if eligible for access to social support and financial concessions
• Getting in touch with national or local charities for advice and peer support

Related links

• Coping with sight loss
• Education and learning
• Family support services
• Driving and alternative transport

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Referral to a specialist centre

If you are based in the UK and would like to be seen in the nearest specialist centre for your eye condition, either to receive a more comprehensive genetic management or just to find out more about current research, you can approach your GP to make a referral or alternatively arrange for a private appointment. 

More information can be found in our “How to see a genetic eye specialist?” page.

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Further information and support

• NHS
• Royal National Institute of Blind People (RNIB)
• Guide Dogs for the Blind Association
• Look UK

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A patient’s perspective

• A story about Hannah as told by her mother

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References

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