Every eye word, explained simply.

Accommodation is the eye's ability to change focus between things far away and things up close. Tiny muscles inside the eye adjust the lens to keep whatever your child is looking at sharp. It happens automatically, in an instant.

Lazy eye means one eye is not developing as strongly as the other. The brain has started preferring the stronger eye, so the weaker eye gets less practice. The good news is that with the right treatment and some consistency, the weaker eye can absolutely catch up.

An anaesthetist is the specialist doctor who keeps your child safely and comfortably asleep during an operation, watching over them the whole time. For children's eye surgery they are experienced with little ones, and they will talk you through the day beforehand.

Anisometropia means the two eyes need quite different glasses strengths because they focus differently. Because the brain gets two unequal pictures, it can start to favour the clearer eye, which is one of the causes of lazy eye. Glasses even the two eyes up so they can develop together.

The aqueous humour is the clear, watery fluid that fills the front of the eye, just behind the cornea. It keeps the eye gently firm and feeds the tissues at the front. When it cannot drain away properly, the pressure inside the eye can rise, which is what happens in glaucoma.

Astigmatism simply means the front of the eye is shaped a little more like a rugby ball than a soccer ball. Because the curve is uneven, light focuses in more than one spot and vision can be blurry at any distance. It is very common, often sits alongside short or long sight, and glasses correct it.

Atropine is an eye drop that gently and temporarily blurs the stronger eye. Used for lazy eye, it is an alternative to patching: with the strong eye blurred, the brain is nudged to use the weaker one. It also helps us measure a child's glasses accurately, and in low doses it can help slow short-sightedness.

An autorefractor is a machine that gives a fast first estimate of a glasses prescription by shining light into the eye and reading how it bounces back. Your child just looks at a picture inside it. The result is then fine-tuned by hand.

These two words describe how many eyes are involved. Bilateral means both eyes; unilateral means one eye only. You will see them on reports, for example a unilateral cataract means a cataract in one eye.

Binocular vision is the two eyes working together as a team, with the brain blending their two pictures into one. Good teamwork gives smooth, comfortable, three-dimensional sight. When the eyes are not aligned, as in a squint, this teamwork is disrupted.

A blocked tear duct means the little drainage channel that carries tears from the eye down into the nose is not open properly. Tears then well up and spill down the cheek, and the eye can get sticky. It is very common in babies and very often clears on its own in the first year, sometimes with a little massage.

Cataract surgery removes the clouded lens from inside the eye so light can reach the retina clearly again. In children the focusing it used to do is then replaced by a lens implant, a contact lens or glasses. Done early, it gives the eye its best chance to develop good sight.

CVI means the eyes themselves may be healthy, but the parts of the brain that make sense of what the eyes see are not processing it typically. A child might see, yet struggle to recognise faces, find a toy in a busy room, or judge stairs. Understanding how your child sees is the key, and there is a great deal that helps.

A chalazion is a small, usually painless lump in the eyelid caused by a tiny blocked oil gland. It is not an infection and not dangerous. Warm compresses often settle it over a few weeks; occasionally a little more help is needed.

Colour vision deficiency, often called colour blindness, means some colours are harder to tell apart, most commonly certain reds and greens. It is usually inherited, far more common in boys, and it does not change over time. Most children adapt easily once everyone understands it.

Congenital means present from birth. A congenital cataract, for example, is one a baby is born with, as opposed to one that develops later in life.

A cataract means the lens inside the eye, normally clear like a window, has become cloudy. When a baby is born with one, it can stop the eye seeing clearly during the most important period of visual development. Surgery removes the cloudy lens, and glasses or a contact lens replaces the focusing it did. Early treatment gives the eye the best chance.

The conjunctiva is the thin, clear, moist layer that covers the white of the eye and lines the inside of the eyelids. When it becomes inflamed the eye looks red or pink, which is conjunctivitis.

Conjunctivitis, or pink eye, is inflammation of the clear layer over the white of the eye, which makes it look pink or red. It can come from a virus, bacteria or an allergy, and often causes watering, grittiness or stickiness. Most cases are mild and settle, though it is worth checking which type it is.

Contact lenses sit directly on the eye to correct focus. In children they are used for particular reasons, such as a big difference between the two eyes or after cataract surgery, and always with guidance on safe, clean handling.

Contrast sensitivity is how well the eye picks out something from its background when the difference is subtle, like grey writing on a slightly lighter grey. It is a different measure from how small a letter you can read, and it matters for real-world seeing.

Convergence is the way both eyes turn inwards together to point at something close up, like a book or a puzzle. Good convergence lets a child do near work comfortably; when it is weak, reading can feel tiring or the words may seem to swim.

The cornea is the clear, curved window at the very front of the eye. It does most of the eye's focusing as light passes through it. Its clarity and smooth curve matter for sharp sight, which is why conditions like keratoconus, which change its shape, affect vision.

A cover test is a simple, gentle check for a squint. The examiner covers and uncovers each eye in turn and watches how the eyes move. It needs no words from your child, so it works even with babies, and it shows whether the eyes are working together.

Cross-eyed is an everyday way of describing an eye that turns inwards. The medical name is esotropia, a type of squint.

A cycloplegic refraction is a glasses measurement taken after drops have temporarily relaxed the eye's focusing. Children can over-focus and hide their true prescription, so the drops let us measure it accurately. Vision is blurry and bright for a few hours afterwards.

Depth perception, or stereopsis, is the ability to see the world in three dimensions and judge how near or far things are. It comes from the two eyes working together and the brain combining their slightly different views. When the eyes are not aligned, depth perception can be reduced.

Dilating drops widen the pupil so the examiner can see right inside the eye, to the retina and optic nerve. They may also relax focusing to measure glasses accurately. They sting for a moment and leave vision blurry and light-sensitive for a few hours, so bring a hat or sunglasses.

A dioptre is the unit that measures the strength of a lens or a glasses prescription. The further a number is from zero, the stronger the correction. A minus number means short-sighted, a plus number long-sighted.

Diplopia means seeing double, one object appearing as two. It can happen when the eyes are not pointing in exactly the same direction, so the brain receives two pictures it cannot merge. In children it always deserves a check.

The dominant eye is the one the brain tends to rely on a little more, much like being right or left handed. Having a dominant eye is completely normal. It only matters when one eye is doing far too much of the work, as in lazy eye.

Dry eye means the eyes are not staying comfortably moist, either because there are too few tears or they evaporate too quickly. Eyes can feel gritty, tired or, oddly, watery as they try to compensate. It is less common in children but does happen, especially with a lot of screen time.

Esotropia is a squint where one eye turns inwards, towards the nose, while the other looks straight ahead. It is one of the most common types of squint in children. Treatment depends on the cause and may involve glasses, patching, or surgery.

Exotropia is a squint where one eye drifts outwards, away from the nose. It may come and go at first, often when a child is tired or daydreaming. A check tells us how often it happens and what will help.

Eye drops deliver medicine or moisture straight to the eye. Getting them in can be tricky with a wriggly child; laying them down and dropping into the inner corner, then letting them blink, often works. There is a knack to it, and it does get easier.

A full eye examination checks how well each eye sees, how the eyes work together, the need for glasses, and the health of the eye inside and out. For children it is done with games, pictures and gentle tests, at their own pace.

Six small muscles attach to the outside of each eye and move it up, down and side to side, and keep the two eyes pointing together. When these muscles are not perfectly balanced, an eye can drift, which is a squint. Squint surgery gently adjusts these muscles.

Eyelids protect the eye, spread tears and keep the surface healthy, so problems like lumps, turning in or out, drooping or infection can affect comfort and sometimes vision. Most are easily treated once we know which one it is.

Fixation is the eye settling on and holding steady on something, like a face or a toy. Steady fixation is a sign the eye and brain are working well together. Watching how a baby fixes on and follows a face is one of the simplest early checks.

A follow-up is simply the next appointment to see how things are going. Many eye conditions in children are watched over time, because how they change tells us as much as a single visit. A follow-up is routine, not a sign that something is wrong.

The fovea is a tiny pit at the centre of the retina where sight is sharpest. It is what you use to read, recognise a face or thread a needle. The whole of central, detailed vision depends on this small spot.

The fundus is the inside back wall of the eye, including the retina, the macula and the head of the optic nerve. When a doctor looks at the fundus, often after dilating drops, they are checking the health of these vital parts.

Fusion is the brain's trick of taking the slightly different picture from each eye and blending them into a single, solid image. It is the foundation of depth perception. A squint can interrupt fusion, which is one reason we treat squints.

Glasses are the simplest, safest way to give a child clear focus. They do not weaken the eyes or make them lazy; they let the eyes and brain develop on clear pictures, which is exactly what young eyes need. For many children they are the whole treatment.

Glaucoma in children is when there is too much pressure building up inside the eye. This can damage the optic nerve, the cable that sends visual information from the eye to the brain. It is serious but very treatable, especially when caught early. With the right treatment and regular monitoring, most children do very well.

A GP, your family doctor, is often the first port of call and the one who refers your child on to an eye specialist when needed. They are a good starting point when you are not sure where to go.

Hyperopia, or long-sightedness, means the eye focuses light a little behind where it should, so close-up things blur first and, if strong, distance too. A degree of it is normal in young children and often lessens as they grow. When it affects sight or triggers a squint, glasses help.

An intraocular lens is a tiny artificial lens placed inside the eye to do the focusing job of a natural lens that has been removed, for example during cataract surgery. It sits permanently and invisibly inside the eye.

The iris is the coloured ring of the eye, blue, brown, green or hazel. It works like a camera's aperture, opening and closing the pupil at its centre to control how much light gets in.

The Ishihara test uses cards dotted with coloured spots that form a number or a trail. A child who sees certain colours differently will read them differently, which reveals a colour vision deficiency. It is quick and painless.

Keratoconus is when the normally dome-shaped cornea gradually thins and bulges into more of a cone, which blurs and distorts vision. It usually appears in the teenage years. Caught early, treatments can hold it steady, so early diagnosis really matters.

The lacrimal gland, tucked above the outer edge of each eye, makes the watery part of tears. Those tears wash, protect and nourish the surface of the eye before draining away through the tear duct.

Lazy eye is the everyday name for amblyopia, where one eye has not developed full sight and the brain favours the other.

Sometimes a child who struggles at school turns out to have an undetected vision problem making reading and focusing hard work. Vision is not the cause of every learning difficulty, but it is always worth ruling out, because it is so treatable when it is a factor.

The lens sits just behind the pupil and fine-tunes the eye's focus, changing shape to keep near and far objects sharp. It should be crystal clear; when it clouds, that is a cataract.

Leukocoria is a white reflection in the pupil, sometimes first noticed in a photo where one pupil glows white instead of red. It can have several causes, some needing prompt attention, so a white pupil should always be checked quickly.

A LogMAR chart is a modern, more precise version of the eye chart, with the same number of letters on every row. It is the standard used in eye clinics because it measures small changes in vision accurately.

Long-sightedness is the everyday name for hyperopia, where close-up things blur first.

The macula is the small, central part of the retina responsible for sharp, detailed, straight-ahead vision and much of your colour vision. The very centre of it is the fovea.

Monitoring means keeping an eye on a condition over time with regular checks, rather than treating straight away. For many childhood eye conditions, how something changes is the most useful information, and watching closely is an active, sensible plan, not doing nothing.

Myopia, or short-sightedness, means your child can see things up close quite well but things in the distance start to blur. It is very common and tends to progress during childhood as the eye grows. Glasses or contact lenses correct it, and there are now treatments that can help slow how fast it progresses.

Myopia control is a set of modern approaches, special glasses or contact lenses, low-dose atropine drops, and more time outdoors, that aim to slow how fast short-sightedness increases through childhood. The goal is to keep the final prescription lower, which is better for long-term eye health.

Nystagmus is when the eyes make small, repeated, involuntary movements, a wobble or flicker the child cannot control. It can be present from early life or develop later. Understanding the type guides what helps, and many children see better than the movement suggests.

An OCT, or optical coherence tomography, is a quick, painless scan that takes a detailed cross-section photograph of the layers of the retina and optic nerve, without touching the eye. It helps us see fine detail that a normal examination cannot.

Eye ointment is a soothing, medicated jelly put along the inside of the lower lid, often at bedtime. It stays in contact with the eye longer than drops, which is useful overnight or for very young children. It blurs vision briefly as it melts.

An ophthalmologist is a medical doctor who has specialised further in eyes, and who can examine, diagnose, prescribe and perform eye surgery. Dr Claire is a paediatric ophthalmologist, meaning she specialises in children's eyes.

Ophthalmoscopy is the doctor looking into the back of the eye with a bright light and lenses to check the retina and optic nerve. It is often done after dilating drops, which open the pupil for a clearer view.

The optic disc is the spot at the back of the eye where the optic nerve leaves to travel to the brain. Its appearance tells the doctor a lot about the health of the nerve, which is why it is checked in conditions like glaucoma.

The optic nerve is the thick cable of over a million tiny fibres that carries everything the eye sees to the brain. If the eye is the camera, the optic nerve is the cable to the screen. Protecting it is why eye pressure matters.

A dispensing optician is the professional who fits and supplies glasses, helping choose frames and lenses that suit your child and sit correctly. They fill the prescription; they do not test the eyes.

An optometrist tests eyesight, prescribes glasses and contact lenses, and checks for common eye problems. They are often the first person to spot something and refer on. They are not medical doctors, and they work closely with ophthalmologists.

Ortho-K uses a specially shaped contact lens worn overnight to gently reshape the front of the eye while a child sleeps. It is taken out in the morning, giving clearer daytime vision without glasses, and it is one of the tools used to slow short-sightedness.

An orthoptist specialises in how the two eyes work together, and in squints and lazy eye. They do many of the careful measurements and run patching programmes, working hand in hand with the ophthalmologist.

Paediatric simply means relating to children. A paediatric ophthalmologist is an eye surgeon who has trained specifically in children's eyes, which differ from adults' in important ways.

A paediatric ophthalmologist is an eye doctor and surgeon who has done extra training in children's eyes and their particular conditions, and in putting young children at ease. This is Dr Claire's field.

Patching means covering the stronger eye for part of each day. When the stronger eye is covered, the brain has no choice but to use the weaker eye. Over time, that forces the weaker eye to work harder and develop more strength. It is one of the most effective treatments we have for lazy eye, and it works best when it becomes part of the daily routine rather than a battle.

A prism is a special wedge built into a lens that bends light to help the two eyes line up on the same image. Prisms can relieve double vision and help the eyes work as a pair, sometimes avoiding or delaying surgery.

If a blocked tear duct has not cleared on its own, a quick, gentle procedure called probing can open it, passing a fine, smooth wire through the channel. It is usually very effective and, in young children, done under a short anaesthetic.

Prognosis is the likely outcome, what we expect to happen with treatment over time. For most childhood eye conditions caught early, the prognosis is very good, which is the reason we check things sooner rather than later.

Ptosis is a drooping upper eyelid, present from birth or developing later. If the lid covers enough of the eye to block the line of sight, it can get in the way of vision developing, so it is watched and sometimes lifted with surgery.

The pupil is the round black opening at the centre of the iris that lets light into the eye. It is black because it looks into the darkened inside of the eye. It widens in dim light and narrows in bright light.

A red eye simply means the white of the eye looks pink or bloodshot. There are many causes, from a harmless burst blood vessel or mild conjunctivitis to things that need prompt care. How it looks, plus any pain or change in vision, tells us how urgently to act.

The red reflex is the healthy orange-red glow seen when a light shines into the pupil, the same glow that makes red-eye in photos. A normal red reflex is reassuring; a white, dull or absent one is checked promptly. It is a key part of every baby's eye check.

A referral is when one professional sends your child on to another, usually a specialist, with a note about what they have found. Being referred is a good thing: it means the right person will take a proper look.

A refraction is the test that measures exactly what glasses, if any, an eye needs. In young children it is often done with drops that relax focusing so the true prescription shows. It is painless and asks little of your child.

A refractive error simply means the eye is not quite the right shape to focus light perfectly, which is the reason glasses exist. Short-sightedness, long-sightedness and astigmatism are all refractive errors. Glasses or contact lenses correct the focus so the eye can see clearly.

The retina is the thin, light-sensitive layer lining the inside back of the eye, like the film in a camera. It captures the picture and sends it up the optic nerve to the brain. Its central spot, the macula, gives the sharpest detail.

Retinoscopy is a skilled, hands-on way to measure a glasses prescription by shining a light into the eye and watching how it reflects while trying different lenses. It works beautifully even with babies, who cannot read a chart or answer questions.

ROP affects some babies born very early, when the blood vessels of the retina have not finished growing. Most mild cases settle on their own, but because some need treatment, premature babies are screened carefully. Catching it early is what protects sight.

Rods and cones are the millions of tiny light-detectors in the retina. Rods work in dim light and pick up movement; cones work in bright light and see colour and detail. Together they turn light into the signals the brain reads as sight.

The sclera is the tough, white outer coat of the eye, the part we call the white of the eye. It protects the delicate inside and gives the eye its shape.

A vision screening is a quick check, often at school or a clinic, designed to flag children who need a fuller eye examination. It does not diagnose; it catches problems that are easy to miss, because a child rarely knows their sight is not normal.

Short-sightedness is the everyday name for myopia, where distance is blurry but close-up is clear.

A slit lamp is a special microscope with a bright, adjustable beam that lets the doctor examine the front of the eye in fine detail, the lids, cornea, iris and lens. Your child rests their chin on a support while the doctor looks; nothing touches the eye.

The Snellen chart is the familiar wall chart of letters that get smaller row by row, used to measure distance vision. For younger children we swap letters for pictures or matching games that do the same job.

Squint is the everyday word for strabismus, when the eyes do not point in the same direction at the same time.

Squint surgery gently adjusts the small muscles that move the eye, to bring the eyes into better alignment. It is a common, well-established operation done under anaesthetic, often as a day case. It can improve how the eyes work together as well as how they look.

Stereopsis is the medical word for depth perception, the three-dimensional sense that comes from both eyes working together.

Strabismus, which most people call a squint or crossed eyes, is when the eyes do not point in the same direction at the same time. The eyes are controlled by muscles, and when those muscles are not quite balanced, the eyes can drift. This is very common and very treatable.

A stye is a small, tender red lump on the edge of the eyelid from a blocked, infected lash gland. It usually clears with warm compresses. A painless lump further from the edge is more likely a chalazion.

The tear duct is the small drainage channel running from the inner corner of each eye down into the nose. It carries away tears once they have done their job. In babies it is sometimes slow to open, which causes a watery, sticky eye.

The tear film is the thin, three-layered coat of tears that covers the eye with every blink, keeping it smooth, comfortable and protected. When it is unstable, eyes feel dry, gritty or watery.

Theatre is the operating room, and a general anaesthetic is medicine that lets your child sleep painlessly through an operation. For eye surgery in children this is normal and carefully managed by a specialist anaesthetist. Knowing what the day looks like takes away much of the worry.

Tonometry measures the pressure inside the eye. It can be done with a gentle puff of air or a small probe after numbing drops, and it is important in checking for glaucoma. It is quick and not painful.

Unilateral means one eye only; bilateral means both eyes.

Visual acuity is the measure of how sharp or clear your child's vision is, often written as 6/6 (the same as 20/20). If we say a child has 50% vision in one eye, they are seeing about half as clearly as we would expect for their age. Our goal through treatment is to bring that number up as close to full as possible.

The visual cortex is the part of the brain, at the very back of the head, that turns the signals from the eyes into the pictures we actually see. Sight is really a partnership between the eyes and this part of the brain, which is why some vision problems, like CVI, begin in the brain.

The visual field is the whole area you can see at once, straight ahead and out to the sides, without moving your eyes. Losing side vision can happen so gradually a child does not notice, so it is measured when needed, for example in glaucoma.

The vitreous is the clear, jelly-like substance that fills the large back chamber of the eye and helps it hold its round shape. Light passes through it on the way to the retina.

A constantly watery eye in a baby is most often a blocked tear duct.

A white pupil, or a white glow in a photo, should always be checked promptly. The medical name is leukocoria.

Wobbly or dancing eyes is the everyday description of nystagmus, small involuntary eye movements.