Squint and lazy eye

Also called Strabismus, Amblyopia, Turn in the eye

Treatable in early childhood and largely not afterwards. The window closes around seven, which is why the checks matter.

What it is

A squint is an eye that does not point in the same direction as the other. A lazy eye, amblyopia, is reduced vision in an eye because the brain has learned to ignore it.

They are linked: an untreated squint is a common cause of amblyopia, though amblyopia also results from one eye being much more long-sighted than the other, or from a cataract or droopy lid blocking vision.

The time-critical point is the reason this entry exists. The visual system develops in the first years of life and the ability to correct amblyopia declines sharply after about seven. Treated at three or four, most children recover good vision; treated at nine, usually not. Waiting to see whether a child grows out of it is how sight is lost.

Treatment is unglamorous and effective: glasses first, which alone corrects a proportion, then patching or drops to make the stronger eye work less, and sometimes surgery for the squint itself.

**A squint appearing suddenly in an older child or adult is a different matter entirely** and needs urgent assessment, because it can mean a nerve palsy, raised pressure in the head, or a tumour.

Signs you might notice

An eye that turns in, out, up or down, constantly or intermittently.

Closing or covering one eye, or tilting or turning the head to look at things.

Sitting very close to the television, or holding books close.

Poor depth perception, bumping into things, clumsiness.

Squinting or rubbing the eyes, and tiring quickly when reading.

In babies: eyes that do not move together after about three months of age.

Urgent, same day: a squint appearing suddenly at any age; double vision; a white reflection in the pupil in a photograph, which can indicate cataract or retinoblastoma; or a squint with headache or vomiting.

How it can affect day-to-day life

Patching is hard. Children resist it because it deliberately makes them see worse, and adherence is the main reason treatment fails. Rewards, timers, patching during a favourite activity and school support all help.

Children are sometimes teased about glasses and patches, and school being on board about why it is happening changes that.

Depth perception may never be fully normal, which affects some sports and, later, some occupations, and it is worth knowing early rather than at a job interview.

Adults with a long-standing squint can have corrective surgery, and it is often refused as cosmetic. It affects eye contact, employment and confidence, and it is worth pressing.

Vision screening at four to five in England catches many cases. Missing that check is a common route to late diagnosis.

Supporting someone well

Go to the routine vision screening around four to five, and do not skip it.

Get any suspected squint checked, at any age, rather than waiting for it to be grown out of. It will not be.

An intermittent squint in a baby up to about three months can be normal; after that it needs checking.

Take a sudden squint, double vision, or a white pupil reflection as urgent.

Wear the glasses full time. This alone fixes a proportion of cases.

Stick with the patching hours prescribed, and ask for help if it is not happening; the orthoptist would far rather adjust the plan than have it abandoned.

Tell the school so patching is supported rather than mocked.

Ask about surgery for adults with a long-standing squint; it is not purely cosmetic.

Where to get help

A GP practice, health visitor or an optometrist, all of whom can refer to the hospital eye service.

An orthoptist, who is the specialist for squint and amblyopia.

Same-day eye assessment for a sudden squint or double vision.

RNIB helpline on 0303 123 9999 for children's sight loss support.