Crossed Eyes or Walleye (Strabismus): Causes, Symptoms & Solutions

Strabismus, also known as squint, crossed eye or walleye, is a condition whereby your eyes aren’t always aligned. One of the eyes may turn in, out, up, or down while the other eye looks ahead.

Our eyes are controlled by six muscles which work together to point both eyes in the same direction. Those with strabismus, have problems controlling their eye movement and maintaining ocular alignment.

Crossed eyes are more common in young children during the early years of life. They are often referred to as congenital strabismus, if present from birth; however, it can also occur in adults.

Strabismus is categorized according to the direction of the turned or misaligned eye. The different categories are as follows:

• Esotropia (inward turning)
• Exotropia (outward turning)
• Hypertropia (upward turning)
• Hypotropia (downward turning)

What are the types of strabismus?

There are many types of strabismus, including accommodative esotropia, intermittent exotropia and infantile esotropia.

Accommodative esotropia

Accommodative esotropia can be genetic and happens when one is farsighted. When a child over-focuses to see clearly, this can result in one or both eyes turning inwards (squint). Symptoms of accommodative esotropia include double vision, covering one eye when looking at close by objects, and tilting the head. Glasses are typically used to treat this type of strabismus; however, an eye patch or surgery may sometimes also be required.

Intermittent exotropia

Intermittent exotropia can occur at any age and causes one eye to fixate on an object while the other points outwards. Symptoms are varied and can include headaches, trouble in reading, eyestrain, double vision and closing one eye to see distant objects. In some instances, there may be no symptoms experienced by the patients themselves. However, the difference in the directions of the eyes may be noticed by others.

Intermittent exotropia can be treated with glasses, eye exercises or surgery.

Infantile esotropia

Infantile esotropia occurs in infants and starts before they reach six months of age. It causes both eyes to turn inwards when looking at objects nearby and in the distance. Infantile esotropia can start on an irregular basis before becoming a constant occurrence. Surgery is the only way to treat infantile esotropia.

What is the main cause of strabismus?

The main cause of strabismus in adults is strokes. However, the cause of strabismus is not always known. Some people are born with strabismus while others develop it later in life. Other risk factors of strabismus in adults include:

• Graves’ disease - an immune disorder resulting in overproduction of thyroid hormones
• Diabetes
• Guillain-Barré syndrome - a rare condition which affects the nerves causing numbness, weakness, and pain
• Brain injury
• Vision loss from an eye infection or injury
• Botulism - a rare but life threatening illness caused by toxins from bacteria called Clostridium botulinum
• Shellfish poisoning

Strabismus in adults can also occur if left untreated in childhood or has reoccurred.

In children, strabismus usually develops as the result of them trying to overcome a vision problem such as short-sightedness, long-sightedness or astigmatism. In most cases, the cause of strabismus in children is unknown. Most cases of strabismus in children are present at birth or shortly after birth and are known as congenital strabismus. The following disorders are also associated with strabismus in children:

• Infections, such as measles
• Genetic conditions or syndromes such as down’s syndrome
• Developmental issues such as cerebral palsy which impairs muscle coordination and is caused by damage to the brain before birth

Strabismus can also be a symptom of retinoblastoma, a rare childhood eye cancer. If your child has a squint, it’s important to get this seen by a GP as soon as possible to rule out this condition.

What causes eyes to cross suddenly?

A serious neurologic disorder can cause eyes to cross suddenly, especially if accompanied by double vision. In this scenario, urgent medical attention is required, and you should call your doctor immediately.

Symptoms of strabismus

Symptoms of strabismus can come and go, or remain consistent and include:

• Cross eyes
• Double vision
• Loss of vision
• Loss of depth perception
• Uncoordinated eye movements
• Eyes looking in different directions
• Eyestrain
• Headaches

When do the symptoms of strabismus appear?

Symptoms of strabismus usually appear by the time a child is three years old. However, they can appear at any age and older children and adults can also experience symptoms of strabismus.

How is strabismus diagnosed?

A paediatric ophthalmologist will carry out a complete eye examination on anyone who appears to have strabismus and is older than four months. They will spend extra time looking at how their eyes focus and move. During the exam, the ophthalmologist may also look at the patient’s history (including family history, medications and other health problems). They may also carry out the following:

• Visual acuity test – the patient may be asked to read letters off an eye chart
• Refraction – corrective lenses may be used to check the eyes and look at how they focus light
• Alignment and focus tests
• Dilation – they may widen the pupils to examine the internal eye structures and look at their health

The above will also be carried out when diagnosing strabismus in adults.

Treatment of strabismus

Strabismus or cross eyes can be treated and corrected with corrective lenses, surgery, or a combination of the two.

Glasses are usually the first answer to correcting cross eyes in children as sometimes, it can be caused by farsightedness.

Amblyopia or lazy eye usually develops because of strabismus. This is treated by placing a patch over the dominant eye. This forces the brain to use the weaker eye and strengthen its vision.

Failing this, surgery can be required if the eyes still aren’t moving correctly. Injections into the eye muscles can help to align the eyes by weakening them. However, the effects are not long lasting (usually less than 3 months).

Surgery can be undergone to treat strabismus and fix the eye’s misalignment, improving vision and appearance. By undergoing surgery and helping your eyes work together, you can prevent health symptoms such as frequent migraines, eye strain and fatigue.

Opticians recommend patients with strabismus undergo treatment as soon as possible and before the age of 14 so that these health issues can be addressed. After the age of 14, strabismus surgery is only carried out for cosmetic purposes.

Can you fix cross eyes?

Alternative ways to fix cross eyes include the following:

Contact lenses

Just like glasses, contact lenses can be used to correct refractive errors. In some cases of strabismus, this will reduce the eyes’ focusing efforts, allowing them to stay straight.

Prism lenses

These lenses bend light entering the eye, reducing the amount of turning the eye must do to look at objects.

Orthoptics

These are eye exercises used for certain types of strabismus.

Medications

Eye drops, ointments, and botulinum toxin type A injections (Botox) can be used to treat crossed eyes problems by weakening an overactive eye muscle.

What can happen if strabismus is not treated?

If strabismus is not treated, it could get worse and lead to further complications including the following:

• Lazy eye (amblyopia)
• Blurry vision, which can affect day-to-day activities and school work
• Eye strain and fatigue
• Headaches
• Double vision
• Low self-esteem regarding one's cross-eyed appearance

In addition to this, if it is not addressed, a serious underlying medical condition such as a brain tumour is overlooked.

What can be expected after treatment for cross eye?

After treatment for cross eye, the patient will be required to book a follow-up appointment. At the follow- up appointment, the doctor will check to see whether any adjustments are required.

It is crucial that strabismus is caught and treated early in children to prevent permanent vision loss. If treated early, it can result in brilliant vision and depth perception.

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