What causes childhood cataracts?

This is one of the two questions, along with ‘What will my child be able to see in the future?’ that every parent wants to know the answer to. For some people, there is a clear answer to this question. For most people there is not at the moment. And for those of us who have been given a medical reason for our childâ’s cataracts it doesn’t answer the question that may be underneath it: ‘Why my child?’

All cataracts in children have some medical cause: some reason why the child’s eyes did not develop in the same way as other children’s, or some reason for having been damaged. When doctors don’t know the reason for the cataracts, they are called ‘idiopathic’.

Congenital (from birth) cataract causes


Just means that the reason isn’t known and this is very common; for over half of all children who are born with cataracts no cause is found. It may be that as more genetic research is done, more of these cases will be found to be genetic and put in the inherited category.

Infection during pregnancy

Rubella (German measles), Varicella (Chickenpox), Herpes simplex (Cold sore virus), Cytomegalovirus (CMV) and Toxoplasmosis are all infections that, if caught by the mother during pregnancy sometimes cause cataracts in the baby, usually along with other problems. There have been several cases recently of adults whose own parents were mistakenly told that their cataracts were caused by Rubella and that they would not pass them on to their children going on to have children with cataracts. Cataracts caused by infection in pregnancy are not passed on the child’s own children. The brothers and sisters of a child born with cataract due to their mother having an infection do not develop cataract.


This means that it has been passed down in the genetic ‘blueprint’ for the baby. It can either be something that one or both parents carried genes for, or it can be that there’s been a new mistake in the way the genes were copied as they were passed on to this child. Often, the only result of the ‘mistake’ is the cataract(s).

Sometimes cataracts are related to other inherited eye conditions such as aniridia; your child’s ophthalmologist will tell you if he or she has any other eye conditions as well as the cataract(s).

Sometimes the cataracts are a part of an inherited syndrome that affects other parts of the child’s body as well as the eyes, the most common of these is Down Syndrome, Trisomy 21 (about 10% of children with Down Syndrome have cataracts). Sometimes cataracts are more often found in children with a particular syndrome, for example Turner syndrome, than in other children, but they are not a common feature of the syndrome; most children with Turner syndrome don’t have cataracts.

There are over sixty different syndromes, most of which are incredibly rare (apart from Down syndrome, which is more common), that can cause cataracts alongside other problems. If your child has other symptoms or features that might point to them having wider problems, your child would have some more tests, these would usually be done by a paediatrician. Concerns may include your baby’s head not growing properly or your baby being very floppy and a poor feeder.

Even if you don’t know whether your child’s cataracts were inherited, a genetic counsellor would be able to give you an idea of whether future children in your family may be affected and you can ask to be referred to one if this is important to you.

Persistent foetal vasculature of the eye

Most cases of persistent foetal vasculature or PFV seem to be ‘one of those things’, rather than anything with a cause that can be found.


Cataracts sometimes develop in eyes that have a severely damaged retina due to retinopathy of prematurity which is an eye condition that affects some babies that have been born very prematurely.

Acquired cataract

– means that the child developed the cataract after the first few months of life. This child develops early vision normally and then the eye sight deteriorates.

Metabolic diseases

These are diseases where some system in the body isn’t working properly. Galactosemia is a metabolic disease where the body isn’t able to digest the sugars in milk and this can cause something that looks like a cataract, but actually isn’t, and if the Galactosemia is treated promptly it will go away. All babies, whether or not they are born with cataracts are tested for Galactosemia as part of the newborn ‘heel prick’ tests.

Because cataracts can indicate that there may be other problems with your child, especially metabolic diseases which need quick treatment, the hospital will want to carry out a number of tests, even for babies who otherwise don’t obviously seem to have any problems just to check that they haven’t missed anything.

Infection to the child’s eye

Toxocara canis which can be picked up from dog poo may cause cataracts as can other infections of the inside of the eye (but not common infections of the outside of the eye like conjunctivitis or pink-eye).


This is when physical damage causes the cataract. This sometimes happens during eye surgery or could be something like another child waving sharp scissors.

Drugs / Radiation

Occasionally powerful steroids or other drugs may cause cataracts. Because the other side effects of such drugs are also potentially serious, they would only be given to a very few children where there was no good alternative.


Checked for medical accuracy by Miss Isabelle Russell-Eggitt, Consultant Paediatric Ophthalmologist, Great Ormond Street Hospital, London