Glossary

A strabismus syndrome
is a horizontal strabismus, in which the strabismus angle is more “divergent downwards” and more convergent when looking upwards.
Accommodative dysfunction
is a significant enlargement of strabismus convergens which is a result of looking at something from a short distance.
Accommodative strabismus
is a type of strabismus which is larger in near than far distance. It is frequently accompanied by hyperopia. This type of strabismus usually responds well to treatment by plus lens glasses.
Amblyopia
(poor vision, lazy eye) is an eye disorder characterized by reduced visual acuity in spite of optimum optical correction and lack of organic change in the eye. Amblyopia is the effect of the eye being “turned off” and is caused by strabismus or refraction error. It can be cured by the end of eye development period, i.e. before the seventh year of life. The treatment involves eye patching but at times pleoptical training is applied.
Anisometropia
is a genetically determined and congenital inequality in eyes refraction. Anismometropia is a frequent cause of short sightedness.
Anisometropia
is a genetically determined difference in eyes’ refracting power. It is a common cause of amblyopia.
Astigmatism
is a genetically determined and inborn optical defect characterized by difference in curvature radius in various cross-sections of an eyeball. It does not change during the life and requires correction by cylindrical senses.
A-V Strabismus syndrome
is a type of strabismus, where a strabismus angle varies depending on whether the patient looks upwards or downwards. When a syndrome occurs, the strabismus is more “divergent downwards” and more “convergent upwards”. When V syndrome occurs the strabismus is more “convergent downwards” and more “divergent upwards”.
Bielschowsky's symptom
is a symptom concomitant with superior oblique muscle palsy; it consists in enlargement of vertical strabismus after leaning on the diseased eye side.
Binocular vision
is the ability of the brain to use both eyes at the same time. It develops during the first months of a child’s life and if at that stage Strabismus occurs it prevents the development of binocular vision. Normally in such a situation it is impossible to correct binocular vision even where surgery to straighten the eyes has taken place. It consists of three levels: simultaneous perception, fusion and stereopsis.
Brown's syndrome
is a congenital eyeball movement disorder in which eye movement upward is limited. It may be operated on, but it is currently believed that with time it may resolve itself.
Compensatory head position
is one of the mechanisms compensating for strabismus which means that the head is positioned in such a way, that the angle of strabismus is as small as possible. At times it may occur in nystagmus when “the special head position” moves the eyes towards “silence” which reduces eye movement of nystagmus and corrects vision. It may occur as leaning the head to the side, twisted face, lowering or lifting the chin.
Congenital fibrosis of the extraocular muscles
is a genetically determined non-progressive fibrosis of the extraocular muscles. The eyeballs are usually set differently and downwards with coexistence of fallen eyelids.
Convergence insufficiency
is most often a disability characterised by a convergent movement of the eyeball when looking from a short distance.
Convergence
it is a consistent set-up routine caused subconsciously when looking at something from a short distance.
Diplopia
(double vision) is the perception of two images at the same time in which each of the images comes from a different eye. It can occur independently or after a strabismus surgery. Diplopia can be irritating, although some of patients are able to ignore the second image.
Dissociated Vertical Deviation
(DVD) is a disorder in which a slow upward drift of an eye can be observed. It often occurs in both eyes but in most cases asymmetrically. It is often an element of congenital infantile esotropia.
Double vision
(diplopia) is the perception of two images at the same time. Each image comes from a different eye and can occur independently or after a strabismus surgery. Diplopia can be irritating, although some patients are able to ignore the second image.
Duane syndrome
(DS) is a congenital disorder in which a limitation or lack of eye adduction can be observed. Surgical treatment reduces the concomitant strabismus or the compensatory head positioning. However, the surgery will not restore the adduction movement.
DVD
(Dissociated Vertical Deviation) is a disorder in which a slow upward drift of an eye can be observed. It often occurs in both eyes but in most cases asymmetrically. It is often an element of congenital infantile esotropia.
Exophoria
is a periodic strabismus in which one of the eyes deviates outward. This appears when someone is tired, pensive or when one eye is covered.
Exotropia
(strabismus divergens) is an unparalleled eyeballs’ arrangement in which one of the eyes deviates outward.
Eye obturation
is a treatment of short-sightedness. A special plaster is placed over the good eye thus forcing the affected eye to work alone. This procedure ultimately results in the correction of vision in the affected eye. This treatment is effective only for children.
Fourth nerve palsy
(trochlear) is a cranial nerve palsy which innervates one of the muscle’s moving the eyeball – the superior oblique muscle. As a consequence,the eye is set higher. Positive Bielschowsky’s symptom and head tilt towards the healthy eye is also found.
Fusion
is the second stage of diplopia; at this stage an ability to fuse two images, each coming from a different eye, occurs.
Graves-Basedow disease
is an immune disorder which appears as hyperthyroidism. Stare, ocular movement disorder, strabismus and diplopia are commonly reported.
Heterophoria
(hidden squint) is a periodic strabismus which appears when someone is tired, pensive or when one eye is covered.
Horizontal nyustagmus
is a form of nystagmus in which there is a rhythmical involuntary horizontal movement of the eyes.
Hypermetropia
(long-sightedness) is a genetically determined and inborn optical defect resulting from unusually short eyeball. In children this defect normally corrects itself as they grow older. In case of high amounts of hypermetropia it can cause strabismus convergans. When that occurs it is necessary to correct by glasses or contact lenses. Adults can treat it by laser surgery.
Hyperphoria
(hidden upward squint) is a periodic strabismus which appears when someone is tired, pensive or when one eye is covered.
Hypertropia
(upward squint) is an unparalleled eyeballs’ arrangement in which one of the eyes goes upwards.
Hypophoria
(hidden downward squint) is a periodic downward strabismus, which appears when someone is tired, pensive or when one eye is covered.
Hypotropia
(downward squint) is an unparalleled eyeballs’ arrangement in which one of the eyes goes downwards.
Infantile esotropia
is a wide angle strabismus convergens which appears when a child is about six months old. In later periods of life oblique strabismus, DVD and hidden nystagmus appears. It often requires a surgery.
Lazy eye
(amblyopia, poor vision) is an eye disorder characterized by reduced visual acuity in spite of optimum optical correction and lack of organic change in the eye. “Lazy eye” is the effect of the eye being “turned off” and is caused by strabismus or refraction error. It can be cured by the end of eye development period, i.e. before the seventh year of life. The treatment involves eye patching but at times pleoptical training is applied.
Long-sightedness
(hypermetropia) is a genetically determined and inborn optical defect resulting from unusually short eyeball. In children this defect normally corrects itself as they grow older. In case of high amounts of hypermetropia it can cause strabismus convergans. When that occurs it is necessary to be corrected by glasses or contact lenses. Adults can treat it by laser surgery.
Marcus – Gunn phenomenon
Is a congenital collapse of the upper eyelid which floats involuntarily when eating, chewing or moving the jaw.
Möbius syndrome
A congenital eyeball disorder in which there is a lack of adduction of both eyes and a significant convergent strabismus is observed. Lower limbs’ disorder and limited facial expressions may also occur. The probable cause is the underdevelopment of the sixth and the seventh cranial nerves.
Myopia
(short-sightedness) is a genetically determined optical defect resulting from too long eyeball. In children it usually progresses. Correction by glasses or contact lenses is necessary. Adults can treat it by laser surgery.
Nystagmus
is rhythmical involuntary movement of eyes. Usually it coexists with lower visual acuity. A patient often subconsciously takes a compensatory head position to correct the vision. Nystagamus is incurable but a surgery on extraocular muscles is sometimes conducted in order to reduce the compensatory head positioning or the concomitant strabismus.
Nystagmus
is rhythmical involuntary movement of the eyes. Usually it coexists with lower visual acuity. A patient often subconsciously takes a compensatory head position to correct the vision. Nystagamus is incurable but surgery on extraocular muscles is sometimes conducted in order to reduce the compensatory head positioning or the concomitant strabismus.
Poor vision
(amblyopia) is an eye disorder characterized by reduced visual acuity in spite of optimum optical correction and lack of organic change in the eye. Poor vision is the effect of the eye being “turned off” and is caused by strabismus or refraction error. It can be cured by the end of eye development period, i.e. before the seventh year of life. The treatment involves eye patching but at times pleoptical training is applied.
Prisms
are specially constructed glasses, which by changing the direction of light beams passing through them may have an influence on the setting of the eyes. It is used in treating double vision as well as in diagnosing of the risk of developing double vision following a strabismus surgery in adults.
Progressive paralysis of extraocular muscles
Is genetically determined, characterised by the progressive limitation in the movement of both eyes and associated with a drop of the upper eyelid
Pseudostrabismus
is a false impression of the presence of strabismus’s even though the eyeballs are parallel. It normally results when the eyes are set too wide or too narrow or when there is a wide nasal bridge.
Rotary nystagmus
is a form of nystagmus in which there is a rhythmical involuntary rotary movement of the eyes , around the eyeball’s anterior posterior axis
Severe strabismus
is a type of strabismus which appears suddenly. It may be the result of paralysis of an extraocular muscle or heterophoria decompensation. Usually coexists with double vision. The prognosis is usually positive and there is a significant chance of recovering binocular vision provided rapid treatment.
Short-sightedness
(myopia) is a genetically determined optical defect resulting from unusually long eyeball. In children it usually progresses. Correction by glasses or contact lenses is necessary. Adults can treat it by laser surgery.
Simultaneous perception
is the lowest level of binocular vision; it is a brain’s ability to perceive images from both eyes at the same time.
Sixth nerve palsy
(abducens) is a cranial nerve palsy which innervates the lateral rectus muscle. As a consequence, convergence strabismus and limitation of adduction is found.
Stare
is mostly caused by hyperthyroidism during Graves-Basedow disease.
Stereopsis
is the third and the highest level of binocular vision, which is the ability of spacial vision, 3D.
Strabismus convergens
is an unparalleled eyeballs’ arrangement in which one of the eyes goes towards the nose.
Strabismus convergens
unparallel setting of the eyeballs, in which one of the eyes deviates inward
Strabismus divergens
(exotropia) is an unparalleled arrangement of the eyeballs in which one of the eyes deviates outward
Strabismus fixus
Strabismus is caused by fibrosis of one or many extraocular muscles. Lack of movement in direction opposite to action of the occupied muscle id found. It may appear in acute short sightedness.
Strabismus obliquus
is another form of vertical strabismus. The largest vertical deviation is visible when using the affected eye to look at the nose. It is the result of an inferior oblique muscle hyper function. This usually results in the affected person adopting a compensatory head position, i.e. leaning the head towards the good eye. Surgery treatment is usually successful.
Strabismus paralyticus
is the result of a paralysis of one of the cranial nerves innervating one of the six extraocular muscles, which are responsible for the movement of the eye. It usually coexists with double vision as well as eye movement restriction towards the direction of the corresponding eye. We can distinguish third nerve palsy, fourth nerve palsy and sixth nerve palsy.
Strabismus surgery
it's purpose is to tighten or loosen particular extraocular muscles.
Surgical treatment of strabismus
surgeries are performed under a general anaesthetic and their purpose is to loosen or tighten appropriate extraocular muscles.
Third nerve palsy
(oculomotor) is a cranial nerve palsy which is responsible for innervating four out of six muscles moving the eyeball. It may be congenital or developed. Usually the eye is set divergently and the lower and upper eyelids droop.
Thyroid Ophthalmopathy
is a disorder in the movement of the eyeballs , often with double vision, characterised by a restriction in eye movement restriction and comes together with Hyperthyroidism. It sometimes requires surgery on the extraocular muscles.
Treatment for strabismus
the first stage consists in ocular correction. Sometimes eye-patching method is used. In some types of strabismus surgical treatment is advisable.
V syndrome
is a type of vertical strabismus in which the strabismus is more “convergent downwards” and more “divergent” upwards. Frequently coexists with strabismus obliquus.
Vertical nystagmus
is a form of nystagmus in which there is a rhythmical involuntary vertical movement of the eyes.
Vertical strabismus
is a type of strabismus in which the affected eye goes upwards or downwards. The frequent cause is the strabismus obliquus which is the result of of a superior oblique muscle hyper function or/and an inferior oblique muscle hyper function.

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