Adult strabismus (crossed eyes) is when your eyes are not lined up properly and they point in different directions. One eye may look straight ahead while the other eye turns in, out, up, or down. The misalignment can shift from one eye to the other.
Strabismus affects vision, since both eyes must aim at the same spot together to see properly.
Types of strabismus
There are different types of strabismus. They can be described by the cause or by the way the eye turns.
The following terms describe strabismus 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
An early diagnosis of strabismus will enable more effective treatment. In the past, it was thought that after a “critical period”, strabismus could not be treated.
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.
Strabismus 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
- Eyeglasses or contact lenses. This may be the only treatment needed for some patients.
- Prism lenses. These special lenses are thicker on one side than the other. The prisms alter the light entering the eye and reduce how much turning the eye must do to view objects. Sometimes the prisms can eliminate the eye turning.
- Vision therapy. Your doctor of optometry might prescribe a structured program of visual activities to improve eye coordination and eye focusing. Vision therapy trains the eyes and brain to work together more effectively.
- Eye muscle surgery. Surgery can change the length or position of the muscles around the eyes so they appear straight. Often, people who have eye muscle surgery will also need vision therapy to improve eye coordination and to keep the eyes from becoming misaligned again.