Strabismus

Symptoms depend on age. Young children rarely complain — the brain just turns off the picture from the turning eye. Look for outside signs:

• An eye that turns in, out, up, or down — all of the time or only sometimes (when tired, sick, daydreaming, or focused on near work).
• A constant head tilt or face turn to use one eye more than the other.
• Closing or squinting one eye in bright light or to focus.
• Bumping into things, missing steps, or trouble with depth perception (3D vision).
• Photos that show one pupil reflex pointing differently from the other.

Older children and adults may also notice:

• Double vision that goes away when one eye is covered.
• Eye strain, headaches, or trouble reading.
• Self-consciousness about how the eyes look in pictures or in the mirror. The cosmetic and social burden of adult strabismus is real and well documented ⁶.

Strabismus is not caused by reading in dim light or watching too much TV. The eye muscles, the brain pathways that control them, and a person's glasses prescription all play a role. Common causes by age:

In children:

• Infantile esotropia — a large constant inward turn that starts in the first 6 months of life. Usually treated with surgery.
• Accommodative esotropia — an inward turn caused by farsightedness. Glasses alone can often straighten the eyes.
• Intermittent exotropia — an outward drift that comes and goes, often more obvious when looking far away or when tired.
• Strabismus from amblyopia — a severely amblyopic eye may drift over time.
• Genetics. A child whose parent or sibling has strabismus is at higher risk ⁷.
• Premature birth, Down syndrome, cerebral palsy, and other neurological conditions all raise the risk.

In adults:

• Childhood strabismus that has drifted back.
• Thyroid eye disease (Graves' eye disease). Inflamed eye muscles can pull the eye out of line.
• Stroke or other brain injury. Damage to the cranial nerves that control eye movement (3rd, 4th, or 6th cranial nerve palsies).
• Diabetes-related cranial nerve palsy — usually painful and improves on its own over weeks to months.
• Head trauma, brain tumors, or other neurological disease.
• Myasthenia gravis — eye muscle weakness that comes and goes during the day.

This is why new-onset double vision in an adult is taken seriously — it can be the first sign of a stroke, brain tumor, or thyroid disease ⁸.

Treatment depends on the type, the age, and the cause of strabismus. Most patients combine more than one approach.

• Glasses. A correct glasses prescription, especially for farsightedness, can completely straighten the eyes in accommodative esotropia.
• Prism in the glasses. Small amounts of prism can fuse a slightly misaligned image and stop double vision in adults.
• Treatment of amblyopia. Patching or atropine drops in the better eye, which often improves alignment as well as vision.
• Eye-muscle exercises (orthoptics). Useful for some types of intermittent exotropia and convergence insufficiency.
• Botulinum toxin injection. A small amount of toxin weakens an overacting eye muscle for several months. A Cochrane review supports its use, particularly for small angles or as a temporary measure ⁴. In infantile esotropia, botulinum can sometimes avoid or delay surgery, although many children still need surgery later ⁹.
• Strabismus surgery. The eye doctor tightens or loosens one or more of the small muscles around the eye to realign it. Surgery is done as an outpatient under general anesthesia in children and either local or general in adults. Most patients are back to normal activities within a week.

For adults, treating strabismus is not just cosmetic. Studies of quality of life with and without diplopia show real improvement in self-image, social comfort, and depth perception after surgery ¹⁰. About 1 in 4 adults still has some double vision in side gaze after strabismus surgery, but the central field is usually clear ¹¹.

• Myth: Babies grow out of all crossed eyes. Fact: Eyes that still turn after about 4 months of age should be checked. True infantile esotropia does not go away on its own.
• Myth: Strabismus surgery is just cosmetic in adults. Fact: Adult strabismus surgery improves binocular vision, depth perception, and quality of life — not just appearance ¹⁰.
• Myth: A child can outgrow a turning eye by doing eye exercises at home. Fact: Most types of strabismus do not respond to home exercises alone. Glasses, patching, and surgery are the proven treatments.
• Myth: If the eyes look straight in a photo, there is no strabismus. Fact: Some types of strabismus only appear when the person is tired, sick, or focused. A full exam is the best way to know for sure.