Cataract is a clouding of the normally clear focusing lens inside the eye causing constant blur in the eye. The lens of the eye is located behind the coloured iris. Its job is to help focus light entering the eye.

Cataract is known mainly as a common cause of poor vision in older adults, but it also occurs uncommonly in babies and children (approx 1 in 1000, more so in smaller babies). When cataract is present, vision is lowered, even with the best glasses. In a child, a period of lowered vision can permanently interfere with vision development.

When cataract is present in both eyes of a child, the child sees poorly and parents can usually tell that there is a problem with vision. When only one eye is affected, the child seems to see normally (out of the good eye).

A cataract may make the black pupil of the eye look white or grey. Sometimes eyes with cataract wander out of line or show jiggling movements (nystagmus). Often, though, the eyes look perfectly normal to the parents.

Cataract in childhood may be caused by injury to the eye, or by a problem with the child's general health. Often cataract in just one eye is caused by a tiny defect of development just in that eye (two causes are Lenticonus and PHPV). Sometimes it is passed on to the child from a parent who has had the same problem. We often arrange an appointment for you with an eye genetics specialist to discuss this in greater detail. Sometimes we refer you to a paediatrician to help find out why your child has cataract; in many cases, no cause can be found.

In some cases, vision loss from cataract is so mild no treatment is necessary but regular checkups are needed. Usually, though, the cloudy lens must be removed with surgery before the eye can see well. Cataract surgery is a major eye operation that must be done with the child asleep under general anaesthesia. It can be performed at any age (even in babies just a few days old) and usually is done as soon as is convenient after being diagnosed. Most of the lens is removed using delicate surgical instruments through a small opening into the eye. Usually, the child feels no pain and goes home a few hours after surgery.

In this practice, the surgery is performed by an "Adult" cataract surgeon. All the modern advances in paediatric cataract surgery have been first developed by Adult cataract surgeons who typically do hundreds of such operations a year, FAR more than a paediatric cataract surgeon might do.

The eye needs to be examined in the doctor's office the day after surgery and several more times during the next few weeks. The child has to wear a protective shield over the eye for a while, and activity is restricted for some days. Eye drops and oral medicines are given several times per day during the early weeks after surgery. The drops can be a full-time job for a week or two! Some weeks after the surgery another anaesthetic may be required to remove a suture. Older children need to refrain from sports that have the potential for contact for a month after surgery.

Cataract surgery is very safe, but complications are possible that may harm the eye or lower vision and even cause blindness (very rare). Sometimes the pupil of the eye looks different after surgery (this usually does not affect sight). There is a very small risk of serious bleeding or infection (less than 1/1000). Even years after surgery, related eye problems such as glaucoma or retinal detachment can develop and threaten sight (see below for more details on Glaucoma). For this reason, it is very important for the child who has had cataract surgery to continue seeing the ophthalmologist regularly for many years. To examine the eye properly in an uncooperative young child after cataract surgery, it is occasionally necessary to use general anaesthesia.

Cataract surgery permanently removes most of the lens from the eye, but a small part of it is left behind in some children, and in some cases, this part later becomes cloudy and has to be removed with another operation. The laser can sometimes be used for this purpose.

Many children, especially if they have had a cataract in only one eye, need treatment for amblyopia ("lazy eye") after surgery. Usually, this involves placing a patch over the good eye for at least a few hours a day, "forcing" the child to use the operated eye. Children often object to wearing a patch, but unless this treatment is effectively done, vision may never recover from the harm caused by the cataract. The first few months after surgery are the most important time for treating amblyopia, but some amount of patching may be needed up to about age 8.

Most children who are treated for cataract end up seeing moderately well. Some have a fantastic result. Occasionally, though, even with the best possible treatment, the vision stays low. Children who have cataract in one eye are less likely to have a good result than children with cataract in both eyes (because of asymmetric inputs into the brain).

Optical Correction After Cataract Surgery in Childhood

During surgery, the focusing lens of the eye is removed. After surgery, it is necessary to provide some other means of focusing. There are three commonly used ways to do this:

1. Glasses. Glasses for children who have had cataract surgery usually are quite thick. They provide vision that is very sharp. The main advantage of glasses after cataract surgery is that they carry no risk of harming the eye. The main disadvantages are that older children often object to their appearance, may find it difficult to play sports in them, they are heavy and are not in place 100% of the time.

   Glasses are usually not good for use after cataract surgery on one eye only, because the images from the two eyes cannot be properly combined in the brain when one eye focuses in the normal way and the other looks through a very strong spectacle lens.

   If your child wears thick glasses, you may want to have a few one-liners available for those "helpful" people who feel they need to comment: 'He's starting high school next week", "she's been reading since the day she was born", etc.

2. Contact lenses, worn directly on the front of the eye. Contact lenses provide vision and appearance that is very natural. They can be used after cataract surgery on one or both eyes. Children of all ages usually are quite comfortable wearing contact lenses.

   The main disadvantage of contact lenses after cataract surgery is that in young children (especially between about 1 and 5 years of age) placing them in the eye and removing them for cleaning can be difficult. They can be lost when the child rubs the eye and in some cases need to be replaced often (typically 3-6 times in the first year). With babies and school-age children, family members usually learn to handle contact lenses well in a short time.

   Contact lenses are very safe when properly cared for. Rarely, though, they can cause serious eye infections, especially if care instructions are not obsessively followed. Some children wear contact lenses part of the time and glasses part of the time, depending on their particular needs or want at that moment.

   In this practice, contact lenses are recommended for:

   a) Babies under 12 months
   b) After surgery for dislocated lenses.
   If contact lenses are used we refer you to an experienced optometrist.
   In general, hard lenses are superior to soft lenses. There is a new soft lens material (silicon hydrogel) which will probably become the contact lens of choice when the correct strengths become available in 2005.

3. Intraocular lens, or IOL. An IOL is a tiny artificial lens placed inside the eye surgically, usually during the same operation in which the cataract is removed. The first IOL used in a child was in 1955 (Dr. Choyce, U.K.).

   IOLs provide vision and appearance that is very natural. Their main advantages over contact lenses are that once in place the only attention they need is regular check ups by the ophthalmologist, and they are present constantly to do their job, so the child never has to put up with blurred vision even for a short time. This may result in better long term visual results.

   Once the IOL is inside the eye, it is difficult to remove or replace it. As the eye grows and matures, the focussing power it needs for sharp vision can change. The child who had IOL surgery may still need to wear glasses or contact lenses when older, although they do not have to be as strong as what would be needed without the IOL.

   IOLs have been used in millions of adults who have had cataract surgery within the past 25 years, work very well and are very safe. IOL implantation in children has become popular only within the past few years, and there is still a good deal to be learned about how well it will work and how safe it will be over a lifetime. Most paediatric cataract surgeons offer IOLs routinely after the age of 4, many after the age of 2 and some at all ages (even in babies a few days old!). In this practice we usually recommend IOLs over the age of 2. In the USA there is some research starting on using IOL's in babies under 6 months. Most need a second surgery within 12 months. It is not known if visual outcomes are superior with this approach.

The risk of a surgical complication that might harm the child's eye is marginally higher when an IOL is implanted. A child who has cataract surgery without an IOL may often be able to have one placed in the future with a second operation, but there are risks and disadvantages to secondary lens implantation.

One of the jobs of the natural lens is to adjust the eye's focus from distance to near. None of the three kinds of correction described above does this as well as the natural lens in a child's eye. To make up for loss of focussing adjustment, it is necessary to provide the child who has had cataract surgery with additional focussing correction for seeing up close. This is usually done by means of bifocal or reading glasses, which may be needed even if contact lens wear or IOL implantation is also used.