Babies and children who have cataract surgery are much more likely to have problems (complications) afterwards than adults who have cataract surgery. This may in part be caused by other eye problems that many children with cataracts have, or because young children have very fierce immune systems so it is more likely that inflammation will occur after the operation. A child’s eye is still developing so surgery and post operative complications may upset normal growth of the eye and maturation of the vision pathways in the brain. Most adults who have cataract surgery are older adults and so their eyes don’t have to work for as many years afterwards as a child’s will have to, so it may be that some of the later complications happen just because of the number of extra years a child will be using their eyes.
Some of the problems happen just after the surgery if they are going to happen at all, but some of them (glaucoma and detached retina especially) can happen at any time during the rest of your child’s life.
Amblyopia (lazy eye)
A child’s brain is still developing. The vision part of the brain needs to receive signals from the eyes to develop normally. If the signal from the eye to the brain is poor in the crucial first 2 months of life then even if uncomplicated surgery to remove a cataract is performed the brain will never appreciate fine detail and the child will not later in life read down to 6/6 on the eye chart.
Almost all children with cataracts have some degree of amblyopia and the later the surgery is done (if the cataract has been there since birth), the harder this can be to treat. Amblyopia is lack of development of detailed vision caused by the brain ignoring visual information coming from your child’s weaker eye. Amblyopia can also occur in both eyes if neither eye gives a clear picture of the world to the brain. This occurs in bilateral cataracts or if the baby has a delay in obtaining contact lenses or glasses to focus eye sight after having had the cataracts removed
Ambylopia is the biggest cause of poor vision after surgery in unilateral cataract eyes and the reason for all the visual stimulation and patching that is needed to re-train your child’s visual system (eyes and brain) after any childhood cataract surgery if one eye is ‘stronger’ than the other.
Delayed Vision Maturation
After cataract surgery it may appear that your child can’t see anything for a long time (sometimes months) out of the operated eye(s). This is especially a problem in children who have a general delay in their development such as children with Down syndrome (Trisomy 21) and for children who develop Nystagmus (wobbly eyes). A child who may have appeared blind at 4 months of age yet may develop quite good vision by one year of age if there are no other problems with the eye or brain.
Glaucoma
Glaucoma is damage that happens to the optic nerve (the ‘data cable’) that goes out of the back of the eye to the brain, caused by the pressure in the eye being too high. Sometimes this happens quite soon after surgery, especially when the problem is caused by the drainage channels (angles) that allow the aqueous humour to drain out of the eye getting blocked by swelling or debris from the surgery or by a reaction to the steroid eye drops. This type of glaucoma is called closed-angle or acute glaucoma.
Some children develop a different type of glaucoma (known as open angle glaucoma) later, up to 30 years + later, and this is the reason that children who have had cataract surgery should have the pressures in their eyes checked, and their optic nerve checked by looking into the eye regularly for the rest of their lives.
Neither of these checks hurt, although measuring the pressures can feel strange. While your child is too young to sit still, or if they have learning difficulties that make it hard for them to sit still while this is done, she or he may need to have a light anaesthetic (an examination under anaesthesia or EUA) whenever these checks are done.
Children who have other eye problems or who have small eyes (microphthalmos), nuclear cataracts or PFV (persistent foetal vasculature, also known as PHPV in some older texts) are more likely than average to develop glaucoma. The younger the child is when they have their surgery, the greater the risk that they will develop glaucoma.
The more obvious symptoms of glaucoma are red eyes that are watery but not sticky or a hazy-looking cornea with the eye looking as if it has changed colour. Glaucoma in young children is usually painful and they are miserable and off their feeds and they are more upset in bright light. If your child develops any of these symptoms, you should get an appointment with your ophthalmologist promptly. It is also very common for there to be no obvious signs that you can see.
Glaucoma in children or young adults is complicated to treat and may lead to a serious loss of vision. If your child develops glaucoma you may want to ask to be referred to a specialist who treats a lot of cases of childhood glaucoma. Your ophthalmologist may suggest that your child should go to another more specialised ophthalmologist for this reason.
Squint (strabismus, cross eyes or ‘wall eye’)
A lot of people think of a squint as when someone screws up their eyes but to specialists it means that the eyes point in different directions to each other so the term can be a confusing one.
A squint is where the eyes don’t move together and one eye turns out (exotropia / wall-eye) or inwards (esotropia / cross-eyes). Sometimes an eye turning is the first indication of a cataract, but it also happens very often after cataracts (in one or both eyes) have been removed. Treating the amblyopia (lazy eye) does not straighten out the eyes, but helps the vision. Surgery on the eye muscles to improve cosmetic alignment of the eyes will be more successful if the vision in the weaker eye has been improved by patching treatment first. If a squint is only noticeable when a child is tired or unwell then surgery is rarely helpful. If a squint is very variable then surgery can only alter the position about which it varies not straighten the eye totally all the time.
Strabismus can be a bigger problem for older children who develop cataracts later on and an eye turns after they’re used to seeing through both eyes aligned together. It may leave them with mis-matched images from each eye and double vision.
Squint can also be a problem for older children and adults in that they may feel self-conscious about their appearance.
After-cataract (lens pearls, Elschnig’s Pearls, capsule thickening, posterior capsule opacification, PCO, cataract regrowth, clouding and quite a lot of other names)
This capsule (bag) that the lens proteins were in, becomes opaque (cloudy) within a few months after cataract surgery if it is left inside the eye at the operation. Often, the capsule is not totally removed during cataract surgery as the capsule is used to place a new lens implant in the correct position in the eye either at the first surgery otherwise, a rim of capsule is left to allow lens implantation at a second operation when the child is older.
A central gap is made at the first operation or at a second operation for the child to see through (posterior capsulotomy). If this gap becomes too small or closes over then it is as if the cataract has grown back. Sometimes, as a few cells from the original lens always remain in the eye after the cataract is removed, they start to grow in a string of small cloudy lenses ‘lens pearls’ or ‘Elschnig’s pearls’ and these grow across the vision gap in the capsule.
This is a very common complication; it happens to almost all children who have an implant (IOL) fitted. The surgery to remove the after-cataract is usually minor. In older children if there are only a few lens pearls or only clouding of the lens capsule then the gap can be widened with laser surgery.
Damaged pupil
This is where the pupil (black dot) in the centre of the eye becomes oval instead of round or moves off-centre. It’s common after cataract surgery in young children and more common that this will be noticeable if your child’s iris is a light colour.
The pupil may also become rigid, usually smaller and less able to open and close according to how much light there is.
It is rare that damage to the pupil causes any problems to your child, although a small, rigid pupil may make eye examinations and any future surgery more difficult.
Infection inside the eye
This is called endophthalmitis and is usually due to a bacterial infection of the inside of the eye after surgery. It is rare (less than 1 in 400 operations) but when it does happen, it is serious and needs to be treated with emergency further surgery to put antibiotics inside the eye. Children with endophthalmitis may lose all vision in the eye. It is the reason that cataracts in both eyes are usually operated separately rather than at the same time.
Nystagmus (wobbly eyes)
About half the children who have cataracts removed from both eyes will get nystagmus (wobbly eyes). Some children will also develop it even if they only have a cataract in one eye regardless of whether they have the cataract treated or not. It also happens often with other eye conditions such as albinism and sometimes happens alone for no obvious reason.
Nystagmus is when the eyes move backwards and forwards quickly instead of looking steadily straight. It seems to happen because the brain finds it hard to control the eye muscles properly and it can make it harder for your child to see well. However it is very rare that your child will be aware of the movements. The world does not seem to wobble to them. It is just blurry. Nystagmus can make it harder to improve the weaker eye as patching may make the wobble worse. Nystagmus can be annoying and add to your child’s visual difficulties it often develops because vision wasn’t working very well and it just makes things worse again. Nystagmus Network is a UK support group who have a lot more information about the condition.
Detached retina and retinal bleeds
Rarely, the retina (the light sensitive film at the back of the eye) may bleed a little after cataract surgery. Usually this gets better and doesn’t cause any more visual loss, but if it happens to the macula (the area that picks up the central, most detailed vision) it can cause a bigger loss of vision.
A detached retina is an uncommon problem. The retina comes away from the normal position in the back of the eye and stops sending a picture to the brain. Retinal detachment rarely happens in childhood and is more commonly a complication of cataract surgery in young children that only happens when they are adults. If the signs of detachment are detected early then the retina may be reattached successfully. However, if this does occur in a young child often it is detected late and surgery restores little sight.
Checked for medical accuracy by Miss Isabelle Russell-Eggitt, Consultant Paediatric Ophthalmologist, Great Ormond Street Hospital, London