What is Strabismus, Cross Eyes & Convergence Insufficiency?

Strabismus is a word that means while one eye looks at the object you want to view, the other eye looks elsewhere. The name of this condition originated from the Greek word strabismós, which means “to squint”.


When reading, a person with strabismus or turned eye convergence excess, may experience painful and inconvenient symptoms. These symptoms might include:

  • Eye strain
  • Blurring of vision
  • Double vision and
  • Headaches

Usually the brain will ignore the visual information coming from a misaligned eye, which can itself cause problems such as lazy eye or squint eye. But when a person with convergent strabismus tries to focus on something at short range, this causes a conflict in the visual information being processed by the brain, and the visual images become confused.

Not only does strabismus cause vision impairment, but it can also be psychologically damaging. It can impact a person’s self-esteem since it hinders the ability to make normal eye contact with others during conversation, which often leads to the affected person feeling embarrassed and awkward.

What Are the Causes of Strabismus?

Strabismus can be caused by neurological or anatomical issues that impede the control and function of an eye’s extraocular muscles, which regulate eye position and movement, causing both eyes to be misaligned in relation to each another. These issues may stem from the eye muscles themselves, or in the brain’s nerves or vision centres that manage binocular vision.

The Three Types of Strabismus

Types of strabismus or cross eyes compared to normal eyes

Types of Strabismus


When the misaligned eye looks inward, it’s called esotropia, or being cross eyed or having squint eye in colloquial terms. A specific example of esotropia that occurs intermittently is strabismus and convergence excess. In this case, the eyes may converge well enough to focus on an object in the distance, but may have trouble aligning to concentrate on a closer subject.


Exotropia is when one or both eyes are turned outward away from the nose; it is the opposite of being cross eyed. Various vision and physical health issues can be caused by eyes that do not focus and work together. When this occurs, the brain receives two different visual images; one is what the straight eye sees, and the other is what the eye facing outward sees. To prevent double vision, the brain will ignore the image that the turned eye is sending. This may cause the turned eye to deteriorate and eventually affect the ability to see.


Hypertropia is when the eyes are vertically misaligned, specifically when one eye is turned upward. It is the least common type of strabismus. When this happens, the brain receives two different visual cues; one from the straight eye and the other from the misaligned eye. The brain usually shuts off the signal it receives from the misaligned eye and focuses on what the unaffected eye is sending. This causes the misaligned eye to become weaker and eventually cause unbalanced vision.

Strabismus in Babies and Children

Baby with Esotropia in both eyes

Strabismus in babies and children

It is believed that as many as 5 percent of all children are born with some type or level of strabismus. If either parent has strabismus, the likelihood that the child will also develop the eye condition is high. Children who have strabismus may experience double vision or eye strain. The condition in children will not go away by itself, meaning it will require treatment.

It is common for children who have this condition to be negatively perceived by other children. They can develop a high level of self-consciousness, anxiety and emotional distress, all of which can lead to emotional and mental health disorders.

Book an Eye Exam with Microprism Optics Today

Our speciality behavioural optometrist, Dr Michael Christian PhD, has extensive experience in putting the latest scientific neuroplasticity theories into practice. Combining this with cutting-edge prism technology, he works to help improve convergent strabismus symptoms in his patients. If you have strabismus, cross eyes and convergence insufficiency, or any other eye difficulty, call our Docklands clinic today for a thorough eye examination on (03) 9606 0330.


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