What is Squint?

A squint is a condition in which the eyes do not align properly. One eye turns inwards, upwards, downwards, or outwards, while the other one focuses at one spot. It can happen all the time or intermittently.

This usually occurs because the muscles that control the movement of the eye and the eyelid, the extraocular muscles, are not working together. As a result, both eyes are unable to look at the same spot at the same time. It can also happen because a disorder in the brain means that the eyes cannot correctly coordinate. Squint also makes binocular vision impossible, so it is harder for the person to appreciate depth perception.

Types of Squint

There are different types of. They can be described by the cause or by the way the eye turns.

The following terms describe squint by the positions of the eye:

  • Hypertropia is when the eye turns upwards
  • Hypotropia is when the eye turns downwards
  • Esotropia is when the eye turns inwards
  • Exotropia is when the eye turns outwards

Early diagnosis of squint will enable more effective treatment. In the past, it was thought that after a “critical period”, squint s could not be treated. While treatment up to the age of 6years is believed to be most effective, squint can be treated at any time.

Signs and Symptoms In Children

The sign of a squint is fairly obvious from an early age. One of the eyes does not look straight ahead. A minor squint may be less noticeable. Infants and newborns may go cross-eyed, especially if they are tired. This does not mean that they have a squint. Parents can check with their doctor. If a child has one eye closed or turns their head when looking at you, this could be a sign of double vision and a possible squint. It is a good idea to see a doctor. Squint is normally either present at birth or it develops in the first 6 months after birth.


Squint Can Be:

  • Congenital, meaning a person is born with it
  • Hereditary, or running in families, suggesting a genetic link
  • The result of an illness or long-sightedness
  • Due to a lesion on a cranial nerve
  • If the eye cannot focus the light as it comes in through the lens, this is known as a refractive error.

Other Problems that Can Lead to Strabismus Include:

  • Myopia, or short-sightedness
  • Hypermetropia, or long-sightedness
  • Astigmatism, where the cornea is not curved properly
  • A refractive error tends to make the affected eye turn inward, in an attempt to get a better focus.

Squint that results from refractive errors tends to emerge later on, usually around the age of 2 years or older. Hydrocephalus can also lead to squinting. Hydrocephalus is a condition in which too much cerebrospinal fluid builds up in and around the brain.

Some viral infections, such as measles, can cause strabismus. Other conditions that can cause it to include Noonan syndrome and some other genetic conditions.


Children and babies should have routine eye checks as they develop. If there are signs of strabismus, the physician or optician will refer the child to an ophthalmologist. The ophthalmologist will probably use eye drops that dilate the pupils before the test is done. The Hirschberg test, or Hirschberg corneal reflex test, is used to assess whether the patient has a squint. The ophthalmologist shines a light in the eye and observes where the light reflects from the corneas. If the eyes are well-aligned, the light will go to the centre of both corneas. If it does not, the test can show whether the patient has exotropia, hypertropia, esotropia or hypotropia.

Some people may have more than one tropia at the same time.

Treatment Option:

Prompt treatment reduces the risk of complications, such as amblyopia, or lazy eye. The younger the patient is, the more effective treatment is likely to be.

Treatment Options Include:

  • Glasses: If hypermetropia, or long-sightedness, is causing the squint, glasses can usually correct it.
  • Eye patch: Worn over the good eye, a patch can get the other eye, the one with the squint, to work better.
  • Botulinum Toxin Injection, or Botox: this is injected into a muscle on the surface of the eye. The doctor may recommend this treatment if no underlying cause can be identified and if signs and symptoms appear suddenly. The botox temporarily weakens the injected muscle, and this can help the eyes to align properly.
  • Eye drops and eye exercises may help.

Surgery is only used if other treatments are not effective. It can realign the eyes and restore binocular vision. The surgeon moves the muscle that connects to the eye to a new position. Sometimes both eyes need to be operated on to get the right balance.