Strabismus (crossed eyes) in infants and children
Strabismus, or crossed eyes, is a condition that raises questions and concern among lots of parents. Does my baby have crossed eyes? Are we sure? What can be done to help them? When should we intervene? Is it dangerous? Etc.
This important chapter was written by Dr Miriam Ehrenberg, a pediatric ophthalmologist who is listed on this website under our team of recommended healthcare professionals. So, if you are unsure whether your child has strabismus / crossed eyes, or if you are looking for answers on how you can help him/her – this chapter is for you.
What is strabismus?
It is quite simple. Strabismus is a condition where both eyes do not line up in the same direction. What happens is that most of the time one eye is looking at a specific object, while the other is looking in a different direction. For us to be able to see a sharp and clear 3D image both of our eyes need to be lined up in the same direction.
What causes strabismus?
The answer to this can be divided in two:
Congenital strabismus – simple as it sounds, strabismus that you are born with. This type of strabismus can present anytime between birth and 6 months. Sometimes there is a family history of strabismus.
Acquired strabismus – this type of strabismus always presents after the age of 6 months and usually has a cause, for example: high index prescription lenses, a viral infection, an injury, a lesion causing increased pressure inside the skull.
Who is at higher risk of developing strabismus?
Strabismus sometimes develops in perfectly healthy children, children who do not have any ophthalmologic issues or any other health problems.
It can also occur in children who have a family history of strabismus (grandparents, parents, brothers or cousins)
It can develop in children who have high index prescription lenses. Their refractive error can symmetric (farsightedness, also known as accommodative esotropia), or asymmetric, where one eye has a higher index lens than the other (anisotropy). In addition, it can develop in children with a severe vision disorder in one eye as a result of a congenital or acquired condition, such as congenital cataract or trauma, etc.
There are also certain underlying medical syndromes and conditions where strabismus occurs more frequently (cerebral palsy, down syndrome, albinism and more).
Is strabismus in neonates or infants concerning? When should we see a doctor?
Babies under the age of 3 months can sometimes have crossed eyes. As long as the misalignment disappears within a few seconds and the eyes appear to be lined up most of the time, then this is normal. It is a good idea to point this out to your pediatrician, so he can take a look as well, but this type of strabismus typically resolves spontaneously. If the strabismus is permanent, a medical examination is recommended even if the infant is still very young (and also when they are over the age of 3 months, see below).
Keep in mind that around the age of 3-4 moths, an infant’s eyes are supposed to always be lined up in the same direction and the eyes should never be crossed. If, at this point, you notice that one of the eyes is deviating inward or outward while the other isn’t, your pediatrician should be notified, and the child should be referred to an ophthalmologic examination by a pediatric ophthalmologist.
Repairing this strabismus is very important for the development of proper vision and the development of correct bilateral eye functions. There is no point in waiting for the child to “grow”. On the contrary, it is important to diagnose and treat this problem as soon as possible, to allow for adequate treatment with the best possible results in terms of vision and eye alignment.
Strabismus that develops at a later age requires an ophthalmologic consult and examination. Here too, it is important to seek medical attention as soon as possible and not to wait for things to resolve ‘on their own’.
Is strabismus associated with poor vision?
It depends on the cause of the strabismus.
Sometimes strabismus is a manifestation of poor vision.
Other times permanent strabismus that isn’t treated can lead to the development of a lazy eye (more about this here) and this in turn leads to poor vision.
Are there different types of strabismus?
Yes.
Let’s starts with pseudostrabismus.
Pseudostrabismus is a common condition in children. It is when eyes appear to be misaligned despite the absence of true misalignment. This appearance can be created by certain features in the face such as a wide or asymmetric nasal bridge leading to an eyelid fold that can hide a part of the inner eye, making it seem as though the child has strabismus. How can we tell that this is not true strabismus? We can do this by checking for the corneal light reflex test (see more about this below) and confirming that the reflex appears in the center of the pupils on both sides. This means both eyes are lined up in the same direction.
Once pseudostrabismus is ruled out, the most practical way to classify strabismus is according to its direction:
Exotropia – when the eye deviates outward
Esotropia – when the eye deviates inward, towards the nose.
These are the two most common eye misalignments. There are additional types of strabismus that are not as common such as misalignment upward or misalignment downward.
Esophoria – a type of ‘hidden’ strabismus that is only evident when you close or cover one eye. This is usually an incidental finding (during an examination) that does not have any clinical significance and does not need to be treated.
How is strabismus diagnosed?
Often the parents or family relatives are the first to notice the strabismus. Sometimes the child will complain of having double vision or will need to turn their head to make up for the misalignment. Sometimes the misalignment is mild, and it is discovered during a routine examination or randomly at the pediatrician’s office or at the ophthalmologist’s.
One of the simple tests for strabismus is the corneal light reflex test (Hirschberg test) – this is done by shining a light on the child’s eyes.
If the eyes are aligned, you can see the light reflected near the center of the pupils in both eyes.
When the eyes are misaligned, the light reflection will be at different areas in each eye. In one of the eyes the reflection will be at the center of the pupil and in the other eye it will be on the side, depending on the direction of the misalignment.
A full corneal light reflex test is performed by an ophthalmologist and is more complex, but it is not painful or invasive.
The doctor will ask you some questions and perform some tests with regards to the misalignment such as, is it permanent or intermittent (for example, occurs when the child is tired or staring at something)? Is it always the same eye that is misaligned or does it occur in both eyes (sometimes in the left eye and sometimes in the right eye)? Does the child have a refractive error (do they wear prescription lenses)? Do the muscles of the eye function properly or is there an overactivity or a deficiency in one of the muscles?
The examination obviously includes a full eye examination using special tools such as coloured glasses, glasses with certain filters, prisms, etc. – this depends on the age of the child and the type of strabismus they have. Due to the complexity of things, seeing a pediatric ophthalmologist for a full assessment is recommended.
It is worth noting that a full ophthalmologic examination includes an examination following pupil dilation (with the help of eye drops). Following application of these drops, one must wait between 30-60 minutes for the pupils to dilate. So, even though it is not a difficult examination for a child, keep in mind that it may take time to complete a full exam. It is a good idea to play some games, read a book or spoil the child with a treat while they wait.
How is strabismus treated?
The purpose of treatment is to improve the alignment of the eyes and to allow for both eyes to work together.
Just like everything else in medicine, we always start with history taking, questioning and a physical examination. Once the ophthalmologist has examined the child, we can move onto finding the appropriate treatment.
The type of treatment depends on the cause of the strabismus and its characteristics.
Treatment may include:
The use of prescription lenses
Eye exercises
Adding corrective prism to the prescription lenses – this is an optic addition that the optometrist prepares according to the ophthalmologist’s prescription. The prism aids in shifting rays of light towards the deviated eye, to relieve the discomfort and the double vision that may develop because of the strabismus.
Surgical treatment to repair the muscles of the eye
A combination of the above options
When a person has lazy eye (amblyopia), sometimes we prefer to repair the lazy eye before proceeding to surgical repair of the strabismus, find out more about this here.
What is surgical correction of strabismus?
Before we dive deep into the details of the surgery itself, it is important that we go over some basics about the structure of the eye and eye movements.
The eye is a circular organ that sits in the orbit and is controlled by 6 muscles that work by pulling in different directions – upward, downwards, to the sides and diagonally. Each one of these muscles pulls the eye in a different direction, and with the help of our marvelous nervous system, our eyes are controlled in a way that allows both eyes to move in the same direction and to follow the same object.
In strabismus surgeries we attempt to restore the balance and coordination between the two eyes by weakening eye muscles that are too strong or by strengthening weak ones.
For example, if a child has an inward misalignment, the surgeon will consider weakening the muscle/s that pull/s the eye inward in order to balance out the muscles responsible for outward deviation and by doing so the eyes line up.
How is surgical repair of strabismus performed? Will we need to spend the night at the hospital?
Surgical repair of strabismus is performed under general anesthesia. The child is typically discharged on the same day, a few hours after the anesthesia wears off. There are no dressings over the eye or any external incisions on the skin surrounding the eye. Surgical repair can be done on both eyes at the same time if needed.
How painful is this surgery?
The pain and discomfort in the eye muscles following this surgery are moderate in severity. The most common complaints are a pulling/pressure-like sensation in the eyes and a foreign object sensation. These signs and symptoms last only a few days. Analgesics (acetaminophen/ibuprofen) aid in reducing the pain and discomfort.
What kind of treatment is required at home after the surgery?
The child is usually prescribed eye drops by the surgeon. These need to be applied at home. Most patients will have some redness on the part of the eye that is white following the surgery. This resolves slowly over several weeks.
When can the child return to their daily activities?
Most children return to their daily activities about a week following the surgery. It is recommended to avoid swimming at the beach/pool/hot tub for about a month following surgery. Showering is allowed. It is also recommended to avoid strenuous physical activity. Vision typically improved the day following the surgery. The results of the alignment are examined in several stages following the surgery.
What do potential complications of strabismus surgery include?
Strabismus surgeries have high rates of success. But just like any other surgery, strabismus surgery has its risks and complications.
Firstly, there are general complications such as complications associated with general anesthesia, infections, bleedings, etc. Fortunately, these are very rare.
When it comes to this surgery in particular, there is a risk of remaining misalignment – that is, that the surgery is not completely successful and there remains some misalignment or that excessive repair of the misalignment occurs causing recurrent strabismus and double vision. Usually, when a patient develops double vision following the surgery, it is temporary and resolves within several days.
Most people experience a significant improvement in their eye alignment after a single surgery. Sometimes the surgery results in partial improvement only, and a second surgery is required. It is important to keep in mind that changes to the alignment of the eyes may still occur a long time following the first successful surgery.
In summary, this is a very important topic in pediatric ophthalmology. It requires precise diagnosis and careful management by a pediatric ophthalmology specialist to allow the child’s vision to develop properly and to prevent the development of lazy eye. So, if you’ve noticed that your child has crossed eyes – make sure to see your pediatrician or a pediatric ophthalmologist as soon as possible.
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