{"id":1941,"date":"2026-10-20T08:54:04","date_gmt":"2026-10-20T08:54:04","guid":{"rendered":"https:\/\/laseristanbulclinic.com\/eye-health\/conditions\/squint-strabismus-causes\/"},"modified":"2026-10-20T12:58:55","modified_gmt":"2026-10-20T12:58:55","slug":"squint-strabismus-causes","status":"publish","type":"page","link":"https:\/\/laseristanbulclinic.com\/en\/eye-health\/conditions\/squint-strabismus-causes\/","title":{"rendered":"Squint Causes in Children and Adults: Why Does an Eye Turn?"},"content":{"rendered":"\n
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  4. Squint Causes in Children and Adults: Why Does an Eye Turn?<\/span><\/li><\/ol><\/div>\t\t\t

    Squint Causes in Children and Adults: Why Does an Eye Turn?<\/h1>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t
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    \"Illustration<\/figure>\n\t\t\t\t\t\t\t\t\t

    Squint causes depend on age. In children, a squint is often the eye straining to overcome a focusing problem such as long-sightedness, with family history, premature birth and brain or nerve conditions adding risk; sometimes no cause is found. In adults it is usually a muscle or nerve problem, such as diabetes, thyroid eye disease, stroke or head injury. Any new squint needs an eye examination. Prof. Dr. Ahmet Sat\u0131c\u0131 treats squint at Laser Istanbul Clinic.<\/p><\/div>\n\t\t\t\t\t<\/div>\n\t<\/div><\/div>\n<\/section>\n\n\n\n\n

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    What are the main squint causes?<\/h2>\n\t\t\t\t

    A squint, medically called strabismus, happens when the two eyes stop pointing at the same target because something disturbs the muscles that move the eye, the nerves that control them, or the brain’s control of eye movement.<\/strong> The NHS describes a squint as eyes that point in different directions: one eye may turn in, out, up or down while the other looks straight ahead, either all the time or only sometimes.<\/p>\n

    The American Association for Pediatric Ophthalmology and Strabismus (AAPOS) says most strabismus results from an abnormality of the neuromuscular control of eye movement, including the brain’s part in it. That is why the causes of squint look so different from each other: a focusing error, a tendency that runs in a family, a muscle affected by thyroid disease and a nerve affected by a stroke all end in the same visible sign. AAPOS estimates that about 4% of the US population has strabismus, and the Royal College of Ophthalmologists (RCOphth) puts childhood strabismus at 2.1% of UK children.<\/p>\n

    The main squint causes at a glance:<\/p>

    Group<\/th>Examples<\/th>Mostly seen in<\/th><\/tr><\/thead>
    Focusing (refractive) problems<\/th>Long-sightedness (hypermetropia), short-sightedness, astigmatism, a marked difference between the two eyes<\/td>Children<\/td><\/tr>
    Inherited tendency<\/th>Squint or lazy eye in a parent, brother or sister<\/td>Children and adults<\/td><\/tr>
    Birth and pregnancy factors<\/th>Premature birth, low birth weight, assisted delivery, maternal smoking in pregnancy<\/td>Children<\/td><\/tr>
    Brain and nerve conditions<\/th>Cerebral palsy, Down’s syndrome, hydrocephalus, developmental delay, brain tumour, stroke<\/td>Children and adults<\/td><\/tr>
    Poor vision in one eye<\/th>Cataract, scarring, retinal or optic-nerve disease, injury<\/td>Children and adults<\/td><\/tr>
    Nerve or muscle disease<\/th>Diabetes, thyroid eye disease, myasthenia gravis, head injury<\/td>Mainly adults<\/td><\/tr>
    Earlier eye surgery<\/th>Damage to an eye muscle, or an over-correction after squint surgery<\/td>Adults and children<\/td><\/tr>
    Unknown<\/th>No cause found<\/td>Often infants and young children<\/td><\/tr><\/tbody><\/table><\/div><\/div>\t<\/div><\/div><\/div><\/section>\n\n\n\n\n
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    What are the squint eye causes in a child?<\/h2>\n\t\t\t\t

    In children, a squint is most often linked to a focusing problem, an inherited tendency or a birth-related risk factor, and in many children no single cause is identified.<\/strong> The NHS says squints in children are often caused by the eye attempting to overcome a vision problem, such as short-sightedness, long-sightedness or astigmatism, and adds that the exact cause is not always known. The RCOphth guideline notes that childhood strabismus generally begins before the age of 5 and that most affected children are otherwise healthy.<\/p><\/div>\n\t\t\t

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    Long-sightedness (hypermetropia) and other focusing problems<\/h3>

    A long-sighted child has to focus harder than normal. Because focusing and eye-turning are linked, that extra effort can pull one eye inwards, which is called accommodative esotropia<\/strong>. The RCOphth describes it as an inward squint caused by uncorrected hypermetropia (usually more than +2.0 dioptres), usually starting between 2 and 5 years of age and often seen when a child is tired or concentrating on close objects. It makes up 36.4% of childhood esotropia in the guideline, and glasses that fully correct the long-sightedness can straighten the eyes. The guideline also states that hypermetropia and anisometropia (a clear difference in prescription between the two eyes) greatly increase the risk of developing amblyopia (lazy eye) and strabismus.<\/p>

    Short-sightedness (myopia) explained <\/svg><\/a><\/div><\/div><\/div><\/div>\n\t\t\t\t

    Does a squint run in families?<\/h3>

    Yes, a squint can run in families, though it is not certain to be passed on.<\/strong> The NHS says squints sometimes run in families, and AAPOS says strabismus can run in families. The RCOphth lists a family history of strabismus or amblyopia among the conditions associated with squint and recommends a higher level of surveillance for such children. EyeWiki, the American Academy of Ophthalmology’s (AAO) clinical encyclopedia, lists a positive family history among the risk factors for esotropia. If a parent had a squint or lazy eye, an eye check in the early years is sensible.<\/p><\/div><\/div><\/div>\n\t\t\t\t

    Premature birth, low weight and pregnancy factors<\/h3>

    The RCOphth reports that squint is more common after assisted delivery (forceps or caesarean section), in children with low birth weight, including premature babies, and in children with neuro-developmental disorders. It adds that squint linked to a neuro-developmental problem is independently associated with maternal smoking later in pregnancy, maternal illness in pregnancy and low birth weight for gestational age. EyeWiki also lists prematurity, low birth weight and maternal smoking in pregnancy among the risk factors for esotropia, and prematurity and maternal alcohol or substance use for exotropia. These are risk factors, not blame: most children with these factors do not develop a squint, and many children with a squint have none of them.<\/p><\/div><\/div><\/div>\n\t\t\t\t

    Brain, nerve and genetic conditions<\/h3>

    The NHS lists rarer causes: measles, Down’s syndrome, developmental delay, cerebral palsy and other brain or nerve problems. AAPOS adds hydrocephalus (a build-up of fluid around the brain) and brain tumours to the conditions that go with strabismus in children, and the RCOphth also lists craniofacial syndromes and fetal alcohol syndrome. Squint in these children is part of a wider picture, and their care is usually shared with a paediatrician.<\/p><\/div><\/div><\/div>\n\t\t\t\t

    Squints with no known cause<\/h3>

    Some squints appear without any of the above. Infantile esotropia<\/strong>, an inward turn that starts in the first 6 months of life, is described by the RCOphth as idiopathic, meaning no cause is known; the guideline quotes estimates up to 1 in 400 live births. Intermittent exotropia<\/strong>, an outward turn that comes and goes, affects up to 1% of children, usually starts at 2\u20134 years and also has no known underlying cause. The RCOphth notes that parents see it when a child is tired, daydreaming or in bright sunlight, and AAPOS adds that it can show when a child is ill or bored.<\/p>

    Squint type<\/th>Typical start<\/th>Known driver<\/th>Source<\/th><\/tr><\/thead>
    Infantile esotropia (inward)<\/th>Before 6 months<\/td>None known; family history and prematurity are risk factors<\/td>RCOphth, EyeWiki<\/td><\/tr>
    Accommodative esotropia (inward)<\/th>2\u20135 years<\/td>Uncorrected long-sightedness<\/td>RCOphth<\/td><\/tr>
    Intermittent exotropia (outward)<\/th>2\u20134 years<\/td>None known<\/td>RCOphth, AAPOS<\/td><\/tr>
    Sensory squint (inward or outward)<\/th>Any age<\/td>Poor vision in one eye<\/td>AAPOS, EyeWiki<\/td><\/tr><\/tbody><\/table><\/div><\/div><\/div><\/div>\n\t\t\t<\/div>\n\t<\/div><\/div><\/div><\/section>\n\n\n\n\n

    What causes sudden eye turning in a child?<\/h2><\/div>

    A squint that appears suddenly in a child needs a prompt eye examination, because most childhood squints start gradually and a sudden one can occasionally signal a serious problem.<\/strong> The RCOphth lists “sudden onset strabismus” among the possible indications for neuro-imaging, together with headaches, cranial nerve palsies, an abnormal pupil response, optic nerve disease and unexplained loss of vision. It also says that behaviour change or headache in a child with a squint should be considered suspicious of serious neurological disease.<\/p>\n

    Possible explanations a doctor will look for:<\/p>\n