A squint (also known as a strabismus) is a condition that arises because of an incorrect balance of the muscles that move the eye, faulty nerve signals to the eye muscles and focusing faults (usually long sight). If these are out of balance, the eye may turn in (converge), turn out (diverge) or sometimes turn up or down, preventing the eyes from working properly together. Squint can occur at any age. A baby can be born with a squint or develop one soon after birth. Around 5 - 8% of children are affected by a squint or a squint-related condition, which means one or two in every group of 30 children. If a child appears to have a squint at any age from six weeks onwards, it is important to seek professional advice quickly. Many children with squints have poor vision in the affected eye. If treatment is needed, the sooner it is started the better the results. Squint can be a complex condition and not every situation is covered here. Your optometrist will be pleased to give further advice, if needed. Children will benefit from support and encouragement during treatment and you should not be afraid to ask questions which will help you understand the condition. The successful outcome of treatment depends upon everyone co-operating.
What causes squint?
There are several types of squint. The cause is not always known, but some children are more likely to develop it than others. Among the possible causes are the following:
Sometimes a baby is born with a squint, although it may not be obvious for a few weeks. In about half of such cases, there is a family history of squint or the need for spectacles. The eye muscles are usually at fault. If squint is suspected, it is important that the baby be referred for accurate assessment at the earliest opportunity. Sometimes a baby has what is known as ‘pseudo squint’ which is related to the shape of the face, but a baby with a true squint will not grow out of it.
Long sight (hypermetropia)
Long sightedness can sometimes lead to a squint developing as the eyes ‘over-focus’ in order to see clearly. In an attempt to avoid double vision, the brain may automatically respond by ‘switching off’ the image from one eye and turning the eye to avoid using it. If left untreated, a ‘lazy eye’ (amblyopia) may result. The most common age for this type of squint to start is between ten months and two years, but it can occur up to the age of five years. It is usually first noticed when a baby is looking at a toy, or at a later age when a child is concentrating on close work, such as a jigsaw or reading.
Squint may develop following an illness such as measles or chickenpox. This may mean that a tendency to squint has been present but, prior to the illness, the child was able to keep his or her eye straight.
In some cases a difficult delivery of a baby or illness damaging a nerve can lead to a squint.
Isn't a squint just a cosmetic problem?
Certainly the appearance can lead to problems for the child, but a squint is not merely a cosmetic problem. If left untreated, it can lead to a permanent visual defect in the squinting eye. It is never too late to treat a squint which is cosmetically unacceptable and glasses or surgery can give good results in many cases.
How can I tell if my child has a squint?
People often think that they can tell if a child has a squint if the eyes look unusual or the two eyes look different. This is not necessarily a squint. Squints are often difficult to detect, especially in younger children. Older children may complain of eyesight problems such as double vision. If it is suspected that a child has a squint, the Health Visitor, Child Health Clinic, GP or school doctor/nurse should be asked about a referral to an optometrist, ophthalmic medical practitioner or hospital eye clinic for assessment.
What can be done?
Treatment varies accordingly to the type of squint. An operation is not always needed. The main forms of treatment are: