Squint and Eye Alignment in Babies

When to get help

Ask for an urgent appointment, and say specifically that you are worried about the pupil, if you see any of these:

• A white, cloudy or grey pupil, or a white reflection in the pupil in photographs taken with a flash, instead of the usual red-eye effect.
• An eye that has become suddenly misaligned, especially with vomiting, headache behaviour, drowsiness or after a head injury — that combination needs emergency assessment.
• A pupil that is a different size from the other, or an eyelid that has started to droop.
• Eyes that wobble or flicker constantly from side to side.
• An eye that looks larger than the other, or persistent watering and dislike of bright light.

Arrange a routine but prompt appointment — GP, health visitor, optometrist or orthoptist — if your baby's eyes turn in or out constantly at any age, if a squint is still present after about three months, or if a squint that used to come and go is now there most of the time.

Why occasional crossing is normal at first

In the first weeks a baby's eye muscles and the coordination between them are still developing, so eyes drift, cross and wander, particularly when a baby is tired, unwell, or trying to focus on something close. Many parents notice it most during feeds.

The generally used marker is around three months. By then, most babies hold their eyes reasonably steady and aligned most of the time. Occasional drifting after that, in a baby whose eyes are otherwise straight, is usually still nothing; a squint that is present all the time is not, at any age.

Some babies only look like they have a squint. A wide bridge of the nose and broad skin folds at the inner corners cover more of the white of the eye on the inner side, which makes an eye appear turned in when it is perfectly straight. This is called pseudosquint, it is very common, and it disappears as the face grows. It is worth having someone check rather than assuming either way.

Why a squint is treated rather than watched

The eyes send two slightly different images to the brain and the brain fuses them. If one eye is turned, the images do not match, and to avoid double vision the brain suppresses the signal from the turned eye. Over time that eye's vision does not develop properly, which is amblyopia, or lazy eye.

The NHS explains that lazy eye is treatable, and that treatment works best when it is started early in childhood. The American Academy of Pediatrics describes the same principle in its guidance on amblyopia treatment. That is the reason for not adopting a wait-and-see approach with a constant squint: the window in which vision develops does not stay open indefinitely.

What the light in the eyes is for

When a clinician shines a light at your baby's eyes from a short distance, they are doing two things. They are checking where the reflection sits on each pupil, which shows whether the eyes are aligned, and they are checking the red reflex: the reddish-orange glow that comes back from a healthy retina, exactly the effect that produces red eye in flash photographs.

An absent, white or asymmetrical reflex is the sign that matters. It can indicate a cataract present from birth, which the NHS notes should be treated early to allow vision to develop, and less commonly a tumour of the retina. Both are rare and both are treatable, and both are picked up by exactly this check. The red reflex is looked for at the newborn physical examination and again at the six to eight week review.

The photograph point

Take a look at your phone photographs. If flash photos consistently show a red glow in one pupil and a white or yellowish glow in the other, that asymmetry is worth an urgent appointment. Bring the photographs; a clinician can often see immediately what took you weeks to notice.

Do not panic at a single odd photo. Angle, glare, a partly closed eye and phone processing all produce false results, which is why it is the consistent pattern across several images that counts.

What assessment involves

Expect a referral to an orthoptist or eye clinic, where the tests are play-based and painless. They will assess how the eyes move and align, cover and uncover each eye to see how the other responds, check the red reflex, and usually use drops to widen the pupils so the back of the eye can be examined and the prescription measured. The drops sting briefly and blur near vision for a few hours; your baby will be light-sensitive for the rest of the day, so bring a hat or pram cover.

Treatments

Long-sightedness is a common cause of a squint in babies and young children, and correcting it with glasses alone straightens many squints. Glasses for babies are made to be sat on, and modern frames with a soft strap stay on far better than parents expect.

If one eye's vision is behind, patching the stronger eye for part of the day, or using drops to blur it, forces the weaker eye to work. Surgery on the eye muscles is used for squints that glasses do not correct, and it may be done in early childhood. None of these are urgent on the day, but all of them work better the earlier they start.