Hypertropia is a condition of misalignment of the

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s (

strabismus Strabismus is an eye disorder in which the eyes do not properly align with each other when looking at an object. The eye that is pointed at an object can alternate. The condition may be present occasionally or constantly. If present during a ...

), whereby the

visual axis In architecture and urban planning, sightlines or vistas are a consideration in the design of civic structures, such as a stage, arena, or monument. They may determine the configuration of architectural elements in theater and stadium design a ...

of one eye is higher than the fellow fixating eye. Hypotropia is the similar condition, focus being on the eye with the visual axis lower than the fellow fixating eye.

Dissociated vertical deviation Dissociated vertical deviation (DVD) is an eye condition which occurs in association with a squint, typically infantile esotropia. The exact cause is unknown, although it is logical to assume it is from faulty innervation of eye muscles. Present ...

is a special type of hypertropia leading to slow upward drift of one or rarely both eyes, usually when the patient is inattentive.

Presentation

Associated defects

Refractive errors such as

hyperopia Far-sightedness, also known as long-sightedness, hypermetropia, and hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead o ...

and

anisometropia Anisometropia is a condition in which a person's eyes have substantially differing refractive power. Generally, a difference in power of one diopter (1D) is the threshold for diagnosis of the condition. Patients may have up to 3 diopters of anis ...

may be associated abnormalities found in patients with vertical strabismus. The vertical miscoordination between the two eyes may lead to * strabismic

amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

due to cerebral suppression of the deviating eye, particularly when onset occurs well before adolescence, while neural pathways are still highly plastic * impaired

depth perception Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth sensation is the corresponding term for non-hum ...

, especially in the same instances *

diplopia Diplopia is the simultaneous perception of two images of a single object that may be displaced in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occ ...

or double vision, particularly when onset occurs after childhood, when corresponding neural pathways have been so fixed as to prevent the brain from suppressing the deviant image * cosmetic defect, most noticed by parents of a child so affected and in photographs * face turn, depending on presence of binocular vision in a particular gaze *

cyclotropia Cyclotropia is a form of strabismus in which, compared to the correct positioning of the eyes, there is a torsion of one eye (or both) about the eye's visual axis. Consequently, the visual fields of the two eyes appear tilted relative to each ...

, a cyclotorsional deviation of the eyes (rotation around the visual axis), particularly when the root cause is an oblique muscle paresis causing the hypertropia

Causes

Hypertropia may be either congenital or acquired, and misalignment is due to imbalance in

extraocular muscle The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in humans and other animals. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movemen ...

function. The

superior rectus The superior rectus muscle is a muscle in the orbit (anatomy), orbit. It is one of the extraocular muscles. It is innervation, innervated by the superior division of the oculomotor nerve (III). In the primary position (looking straight ahead), its ...

inferior rectus The inferior rectus muscle is a muscle in the orbit near the eye. It is one of the four recti muscles in the group of extraocular muscles. It originates from the common tendinous ring, and inserts into the anteroinferior surface of the eye. It ...

superior oblique The superior oblique muscle or obliquus oculi superior is a fusiform muscle originating in the upper, medial side of the orbit (i.e. from beside the nose) which abducts, depresses and internally rotates the eye. It is the only extraocular muscle ...

, and

inferior oblique The inferior oblique muscle or obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit. The inferior oblique is one of the extraocular muscles, and is attached to the maxillary bone (origin) an ...

muscles affect the vertical movement of the eyes. These muscles may be either paretic, restrictive (fibrosis) or overactive effect of the muscles. Congenital cases may have

developmental abnormality A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

due to abnormal muscle structure, usually muscle atrophy / hypertrophy or rarely, absence of the muscle and incorrect placement. Specific & common causes include: * Superior oblique Palsy /

Congenital fourth nerve palsy Congenital fourth nerve palsy is a condition present at birth characterized by a vertical misalignment of the eyes due to a weakness or paralysis of the superior oblique muscle. Other names for fourth nerve palsy include superior oblique palsy and ...

* Inferior oblique overaction * Brown's syndrome * Duane's retraction syndrome * Double elevator palsy * Fibrosis of rectus muscle in

Graves Disease Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. ...

(most commonly inferior rectus is involved) * Surgical trauma to the vertical muscles (e.g. during scleral buckling surgery or cataract surgery causing iatrogenic trauma to the vertical muscles). Sudden onset hypertropia in a middle aged or elderly adult may be due to compression of the

trochlear nerve The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates a single muscle - the superior oblique muscle of the eye (which operates through the pu ...

and mass effect from a tumor, requiring urgent brain imaging using

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

to localise any

space occupying lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

. It could also be due to infarction of blood vessels supplying the nerve, due to diabetes and atherosclerosis. In other instances it may be due to an abnormality of neuromuscular transmission, i.e., Myasthenia Gravis.

Treatment

In general, strabismus can be approached and treated with a variety of procedures. Depending on the individual case, treatment options include: * Correction of refractive errors by

glasses Glasses, also known as eyeglasses (American English), spectacles (Commonwealth English), or colloquially as specs, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically u ...

Prism PRISM is a code name for a program under which the United States National Security Agency (NSA) collects internet communications from various U.S. internet companies. The program is also known by the SIGAD . PRISM collects stored internet ...

therapy (if tolerated, to manage diplopia) *

Vision Therapy Vision therapy (VT), or behavioral optometry, is an umbrella term for alternative medicine treatments using eye exercises, based around the pseudoscientific claim that vision problems are the true underlying cause of learning difficulties, partic ...

Patching Patching is a small village and civil parish that lies amid the fields and woods of the southern slopes of the South Downs in the National Park in the Arun District of West Sussex, England. It has a visible hill-workings history going back t ...

(mainly to manage

in children and diplopia in adults) * Botulinum toxin injection * Surgical correction Surgical correction of the hypertropia is desired to achieve binocularity, manage

and/or correct the cosmetic defect. Steps to achieve the same depend on mechanism of the hypertropia and identification of the offending muscles causing the misalignment. Various surgical procedures have been described and should be offered after careful examination of eyes, including a detailed orthoptic examination focussing on the disturbances in ocular motility and visual status. Specialty fellowship trained

pediatric ophthalmologists Pediatrics (American English) also spelled paediatrics (British English), is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, pediatrics covers many of their youth ...

and

surgeons are best equipped to deal with these complex procedures.

References

*
AAPOS website on Strabismus, also containing FAQ's on the subject of Strabismus

External links