SynonymsHeterotropia, crossed eyes, squint[1]
Strabismus results in the eyes not aiming at the same point in space. Shown here is a case of the exotropic type
SymptomsNonaligned eyes[2]
ComplicationsAmblyopia, double vision[3]
TypesEsotropia (eyes crossed); exotropia (eyes diverge); hypertropia (eyes vertically misaligned)[3]
CausesMuscle dysfunction, farsightedness, problems in the brain, trauma, infections[3]
Risk factorsPremature birth, cerebral palsy, family history[3]
Diagnostic methodObserving light reflected from the pupil[3]
Differential diagnosisCranial nerve disease[3]
TreatmentGlasses, surgery[3]
Frequency~2% (children)[3]

Strabismus, also known as crossed eyes, is a condition in which the eyes do not properly align with each other when looking at an object.[2] The eye which is focused on an object can alternate.[3] The condition may be present occasionally or constantly.[3] If present during a large part of childhood, it may result in amblyopia or loss of depth perception.[3] If onset is during adulthood, it is more likely to result in double vision.[3]

Strabismus can occur due to muscle dysfunction, farsightedness, problems in the brain, trauma, or infections.[3] Risk factors include premature birth, cerebral palsy, and a family history of the condition.[3] Types include esotropia where the eyes are crossed; exotropia where the eyes diverge; and hypertropia where they are vertically misaligned.[3] They can also be classified by whether the problem is present in all directions a person looks (comitant) or varies by direction (incomitant).[3] Diagnosis may be made by observing the light reflecting from the person's eyes and finding that it is not centered on the pupil.[3] Another condition that produces similar symptoms is a cranial nerve disease.[3]

Treatment depends on the type of strabismus and the underlying cause.[3] This may include the use of glasses and possibly surgery.[3] Some types benefit from early surgery.[3] Strabismus occurs in about 2% of children.[3] The term is from the Greek strabismós meaning "to squint".[4] Other terms for the condition include "squint" and "cast of the eye".[5][6][7] "Wall-eye" has been used when the eyes turn away from each other.[8]

Signs and symptoms

Aligned vergence; how one ideally views objects
Aligned vergence; how one ideally views objects
Arrow/dotted line indicates fixation distance.

When observing a person with strabismus, the misalignment of the eyes may be quite apparent. A patient with a constant eye turn of significant magnitude is very easy to notice. However, a small magnitude or intermittent strabismus can easily be missed upon casual observation. In any case, an eye care professional can conduct various tests, such as cover testing, to determine the full extent of the strabismus.

Symptoms of strabismus include double vision and/or eye strain. To avoid double vision, the brain may adapt by ignoring one eye. In this case, often no noticeable symptoms are seen other than a minor loss of depth perception. This deficit may not be noticeable in someone who has had strabismus since birth or early childhood, as they have likely learned to judge depth and distances using monocular cues[citation needed]. However, a constant unilateral strabismus causing constant suppression is a risk for amblyopia in children. Small-angle and intermittent strabismus are more likely to cause disruptive visual symptoms. In addition to headaches and eye strain, symptoms may include an inability to read comfortably, fatigue when reading, and unstable or "jittery" vision.

Psychosocial effects

Actor Ryan Gosling's strabismus gives him a distinctive look.
Marty Feldman had a long career in comedy.

People of all ages who have noticeable strabismus may experience psychosocial difficulties.[9][10][11] Attention has also been drawn to potential socioeconomic impact resulting from cases of detectable strabismus. A socioeconomic consideration exists as well in the context of decisions regarding strabismus treatment,[9][10][11] including efforts to re-establish binocular vision and the possibility of stereopsis recovery.[12]

One study has shown that strabismic children commonly exhibit behaviors marked by higher degrees of inhibition, anxiety, and emotional distress, often leading to outright emotional disorders. These disorders are often related to a negative perception of the child by peers. This is due not only to an altered aesthetic appearance, but also because of the inherent symbolic nature of the eye and gaze, and the vitally important role they play in an individual's life as social components. For some, these issues improved dramatically following strabismus surgery.[13] Notably, strabismus interferes with normal eye contact, often causing embarrassment, anger, and feelings of awkwardness, thereby affecting social communication in a fundamental way, with a possible negative effect on self esteem.[14][unreliable medical source?]

Children with strabismus, particularly those with exotropia (an outward turn), may be more likely to develop a mental health disorder than normal-sighted children. Researchers have theorized that esotropia (an inward turn) was not found to be linked to a higher propensity for mental illness due to the age range of the participants, as well as the shorter follow-up time period; esotropic children were monitored to a mean age of 15.8 years, compared with 20.3 years for the exotropic group.[15][16] A subsequent study with participants from the same area monitored congenital esotropia patients for a longer time period; results indicated that esotropic patients were also more likely to develop mental illness of some sort upon reaching early adulthood, similar to those with constant exotropia, intermittent exotropia, or convergence insufficiency. The likelihood was 2.6 times that of controls. No apparent association with premature birth was observed, and no evidence was found linking later onset of mental illness to psychosocial stressors frequently encountered by those with strabismus.

Investigations have highlighted the impact that strabismus may typically have on quality of life.[17] Studies in which subjects were shown images of strabismic and non-strabismic persons showed a strong negative bias towards those visibly displaying the condition, clearly demonstrating the potential for future socioeconomic implications with regard to employability, as well as other psychosocial effects related to an individual's overall happiness.[18][19]

Adult and child observers perceived a right heterotropia as more disturbing than a left heterotropia, and child observers perceived an esotropia as "worse" than an exotropia.[20] Successful surgical correction of strabismus—for adult patients as well as children—has been shown to have a significantly positive effect on psychological well-being.[21][22]

Very little research exists regarding coping strategies employed by adult strabismics. One study categorized coping methods into three subcategories: avoidance (refraining from participation an activity), distraction (deflecting attention from the condition), and adjustment (approaching an activity differently). The authors of the study suggested that individuals with strabismus may benefit from psychosocial support such as interpersonal skills training.[23]

No studies have evaluated whether psychosocial interventions have had any benefits on individuals undergoing strabismus surgery.[24]

Other Languages
العربية: حول
беларуская: Касавокасць
български: Кривогледство
bosanski: Strabizam
brezhoneg: Luch
català: Estrabisme
čeština: Šilhavost
dansk: Skelen
Deutsch: Schielen
español: Estrabismo
Esperanto: Strabismo
euskara: Estrabismo
français: Strabisme
Gaeilge: Fiarshúilí
galego: Estrabismo
한국어: 사시 (눈)
Հայերեն: Շլություն
hrvatski: Razrokost
íslenska: Rangeygni
italiano: Strabismo
עברית: פזילה
latviešu: Šķielēšana
lietuvių: Žvairumas
magyar: Kancsalság
македонски: Страбизам
മലയാളം: കോങ്കണ്ണ്
Bahasa Melayu: Juling
Nederlands: Scheelzien
日本語: 斜視
norsk: Strabisme
oʻzbekcha/ўзбекча: Gʻilaylik
polski: Zez
português: Estrabismo
română: Strabism
Runa Simi: Lirq'u
русский: Косоглазие
shqip: Strabizmi
slovenčina: Strabizmus
slovenščina: Škiljenje
српски / srpski: Страбизам
srpskohrvatski / српскохрватски: Razrokost
suomi: Karsastus
svenska: Skelning
Tagalog: Sulimpat
தமிழ்: மாறுகண்
తెలుగు: మెల్లకన్ను
тоҷикӣ: Аҳвалӣ
Türkçe: Şaşılık
українська: Косоокість
اردو: حول (طب)
Tiếng Việt: Mắt lác
粵語: 射籬眼
中文: 斜视