Squint & lazy eye

My toddler's eye suddenly turned in: when a squint is urgent

A turn that has never been there before is a different problem from one a parent has watched come and go since babyhood. Here is how I tell them apart, and which signs move the appointment from this week to today.

by Dr Chan Li Yen · MBBS, MOphth (UM), Fellowship in Paediatric Ophthalmology & Strabismus

Practises at Hospital Kuala Lumpur 13 min read · 2,276 words

Key takeaways

A squint that is genuinely new, in a toddler whose eyes were straight before, needs a children's eye doctor this week rather than at the next school holiday.
Watch whether the turning eye can still travel outwards to the far corner. An eye that stops halfway points to the sixth nerve and needs to be said out loud on the phone.
Double vision, a headache on waking, vomiting with no tummy bug, a drooping lid, an unequal pupil, or a turn after a head knock or a fever move it to the same day.
Scroll your flash photographs before the appointment: they date the turn, and they show whether either pupil ever comes back pale instead of red.
Nobody decides on patching or exercises before somebody has looked at the back of the eye.

Almost every week a parent rings the clinic about an eye that turned in yesterday. The child is two, or three. In every photograph from Raya the eyes were straight. Then one long tired afternoon an eye slid inwards and stayed there, and by bedtime nobody at home is talking about anything else.

Mata juling, a squint, is one of the commonest reasons a small child is brought to see me, and most squints are not emergencies. A turn that is genuinely new, in a toddler whose eyes were straight before, is the one I do not want a family to sit on. Here is how I tell the two apart.

My toddler's eye suddenly turned in, is this an emergency?

Usually not an emergency for tonight, but never a wait and see either. A new turn in a toddler whose eyes were straight before needs a children's eye doctor this week, not at the next school holiday. A shorter list moves it to today.

Go today if the new turn arrives with any of these: your child says they see two of everything, or starts closing one eye to look at you; a headache they wake up with; vomiting with no tummy bug behind it; a lid that has begun to droop; one pupil larger than the other; or a turn that appeared after a knock to the head or during a feverish illness. Each shifts the question from eye muscle balance to whether a nerve or the pressure inside the head is involved.

Everything else is a this week problem, and this week means telephoning in the morning, not giving it a fortnight to settle. I have never regretted seeing a child early for this. I have regretted the other thing.

He never had a squint before, what changed?

The word doing the work in that sentence is "before". A turn noticed on and off since babyhood is a different story from one that arrived on Tuesday, and I ask in that order.

Eyes that drift now and then in the first weeks are ordinary while the pair learn to work together, which is why a newborn who looks cross eyed is usually fine. That window shuts early. Crossing still coming and going past four months should be checked, and a constant turn is worth checking at any age. A toddler who has never crossed and now does sits outside all of it.

The explanation I find most often at this age is focusing effort. A child who is more long sighted than average works hard to keep the world sharp, and in some children that effort drags the eyes inwards with it. Glasses take the effort away and the eyes frequently straighten. Good outcome, and not a diagnosis anyone can make across a kitchen table: it needs dilating drops and a measurement of what each eye does once it stops trying.

Why won't his eye turn outwards?

Because one small nerve may have stopped pulling. The sixth cranial nerve runs to the muscle that swings the eye outwards, away from the nose. When it weakens the eye crosses inwards and, far more tellingly, will not travel outwards past the midline when your child looks that way.

That sign matters more to me than how big the turn looks, and you can check it at home the way I check it in clinic. Hold a toy at your child's eye level, keep the chin still with a gentle hand, and walk it slowly to one side and then the other. Watch whether both eyes reach the far corner. If one stops halfway, say exactly that when you telephone.

The reasons a sixth nerve stops working in a child include head injury, infection, inflammation, migraine and raised pressure inside the head. Injury is the commonest cause described. None of that is settled at home, which is the point of the sign: an inward turn where the eye will not travel outwards is treated as a nerve problem until somebody shows it is not.

An eye that will not travel outwards tells me more than an eye that turns a long way in.

Can a squint be a sign of something in the brain?

It can, and I would rather tell you plainly than have you find it alone at two in the morning. Hydrocephalus and stroke are both on the published list of things that turn a child's eye inwards, and raised pressure inside the head is one of the reasons a sixth nerve fails. That is why a new squint earns an appointment rather than a reassuring reply to your message.

What I will not give you is odds. Nobody publishes a reliable figure for how often a new turn in a toddler has a serious cause, so a percentage quoted at you has been made up. The useful thing was never a number. It is the pattern: a new turn on its own, seen this week; a new turn with headache, vomiting, double vision, a drooping lid or a recent head injury, seen today.

Many of the children I see go home with a pair of glasses and a follow up date, and with something better than reassurance. They go home with a reason.

Why do you want to see the photographs?

Because a squint sits on the same short list of warning signs as a white glow in the pupil, and your phone holds the only record of what your child's eyes looked like three months ago. I ask for it at nearly every first visit.

Scroll back through the flash photographs for two things. First, the last picture in which the eyes are unmistakably straight, which tells me whether this is weeks old or years old. Second, whether either pupil ever comes back pale or white instead of red. The NHS list of retinoblastoma signs carries both a white reflection in the pupil and eyes pointing in different directions, which is why a white glow in a photo is checked alongside a new turn, not instead of it.

A pale glow in one photograph usually has an ordinary explanation, often the angle of the flash, and it still earns a same week look from someone who can see inside the eye. This is history taking, not superstition, and you are the one holding the notes.

Is a squint the same as a lazy eye?

No, and this is the confusion I untangle most often, sometimes twice in a morning. A squint is about where the eyes point. A lazy eye, what we call amblyopia, is about how well one eye has learned to see. Two problems, turning up together often enough for the words to have blurred into one.

The brain links them. When the eyes point in two directions it receives two different pictures, and rather than put up with double vision it begins to ignore the signal from the turning eye. Sight in that eye then stops developing, quietly, with no complaint from your child, because they have never known any other way of seeing. That silence is why learning to spot the drift at home is worth your time, and why nobody waits to see whether a turn settles by itself.

So treatment is not about how the eyes look. Straightening an eye and teaching an eye to see are two jobs on two clocks, and the way two eyes are built to work as a pair is what we are trying to protect.

How fast do we need to be seen, and what happens there?

This week for a new turn on its own, today for a new turn with any of the signs above. In the government system the route runs through a referral letter, a surat rujukan, from the klinik kesihatan or a GP. The sentence that gets a child seen quickly is specific: her eye turned in for the first time last Tuesday and it will not turn outwards. Do not soften that on the phone.

Nobody will ask your two year old to read anything. We watch each eye travel into every corner, check the alignment with a light held in front of the face, put in dilating drops, measure the focusing power of each eye, then look at the retina while the pupils are wide. For what that hour feels like from your child's side, here is how we test a child who cannot read.

One thing that will not happen at a first visit is a patch. Patching and eye exercises come after somebody has looked at the back of the eye, never before, because a patch on the wrong problem buys time a child does not have. If the answer is glasses, that is a good day. If it is something needing a scan, we found it in the week it appeared instead of the term after.

Go the same day if…

Your child says they see two of everything, or starts closing one eye to look at you.
The turn comes with a headache they wake up with, or vomiting that no tummy bug explains.
One eyelid has started to droop, or one pupil looks larger than the other.
The eye turned in after a knock to the head, or during a feverish illness.
You see a white or pale glow in the pupil in a photograph, or in low light.

Common questions

Will she grow out of it, or does a squint need treatment?

A true squint does not grow out. It is unlikely to get better on its own, and a constant turn is worth checking at any age. What does resolve is the ordinary drifting of the first few weeks of life, and the illusion of crossing caused by a wide nasal bridge. Those are different things, and telling them apart is a five minute job with a torch.

My toddler's eye only turns in when she is tired, is that the same thing?

It still needs checking. Any crossing beyond four months of age, whether it comes and goes or sits there all the time, should be looked at. An eye that only turns when a child is tired or unwell is often the first appearance of a turn that later becomes constant, so it is a reason to book, not a reason to relax.

Will he need an operation, or can glasses fix it?

Glasses fix a good number of them. When the eyes cross because a long sighted child is over-focusing, glasses take away the focusing effort and the eyes often straighten, which is why the glasses have to be worn all day and not just for close work. Surgery is considered when glasses do not straighten the eyes fully, and that is a decision made after the drops, not before them.

Should I take a photo or a video of the turn before we come?

Yes, and a video is better than a photo. A turn that comes and goes has a habit of vanishing in a clinic room while a child is alert and interested in a stranger. Film ten seconds of your child looking at something far away, and ten more looking at a toy held close. Bring your old flash photographs too, because they date when the eyes were last straight.

My baby looks cross eyed but the doctor said it is her nose bridge, is this different?

Yes, and that is a real and common finding rather than a brush-off. A wide flat nasal bridge and folds of skin at the inner corners can hide the white of the eye nearest the nose, so straight eyes look crossed, particularly in photographs and when the child glances sideways. A light reflection test and a cover test settle it. One thing worth knowing is that a baby with this appearance can still develop a true squint later, so a reassuring visit is not a permanent all-clear.

Does a new squint mean my child needs a brain scan?

Not automatically. Whether imaging is arranged depends on what the examination shows, particularly whether an eye movement is limited and whether there are other neurological signs. A sixth nerve that is not working, especially alongside headache or vomiting, is the situation in which a scan is arranged quickly. Most children examined for a new turn do not reach that point.

Can too much screen time cause a squint?

No. The published causes of an eye turning inwards are focusing effort, the balance of the eye muscles, and the nerves that drive those muscles. Handphone use is not among them. I say this plainly because a new squint arrives in most households alongside a round of blame, and the blame is misplaced and slows people down.

My mother-in-law says a squint is only about looks and he will outgrow it, is she right?

She is right that it changes how a child looks, and wrong that this is the problem. The real cost is invisible: when the eyes point in two directions, the brain starts ignoring the picture from the turning eye, and the sight in that eye stops developing. Your child will not complain, because they have never seen any other way. That is the part treatment is racing, and it is why an eye turn is a vision question rather than a cosmetic one.

References

NHS · Squint (strabismus) · www.nhs.uk
AAPOS · Esotropia · aapos.org
AAPOS · Cranial nerve VI palsy (sixth nerve palsy) · aapos.org
AAPOS · Strabismus · aapos.org
AAPOS · Accommodative esotropia · aapos.org
AAPOS · Pseudostrabismus · aapos.org
NHS · Retinoblastoma symptoms · www.nhs.uk

By Dr Chan Li Yen. General information only. It does not replace a consultation. If you are worried about your child's eyes or vision, please see an eye doctor.