Hypertropia is a condition of misalignment of the eyes (

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

), whereby the

visual axis In architecture, sightlines are a particularly important consideration in the design of civic structures, such as a stage (theatre), stage, arena, or monument. They determine the configuration of such items as theater (structure), theater and s ...

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, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, i ...

and

anisometropia Anisometropia refers to a condition when two eyes have unequal refractive power. Generally, a difference in power of one diopter (1D) or more is the accepted threshold to label the condition anisometropia. Patients can tolerate 3 D of anisomet ...

may be associated abnormalities found in patients with vertical strabismus. The vertical miscoordination between the two eyes may lead to * Strabismic amblyopia, (due to deprivation / suppression of the deviating eye) * cosmetic defect (most noticed by parents of a young child and in photographs) * Face turn, depending on presence of binocular vision in a particular gaze *

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

or double vision - more seen in adults (maturity / plasticity of neural pathways) and suppression mechanisms of the brain in sorting out the images from the two eyes. * cyclotropia, 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 (extrinsic ocular muscles), are the seven extrinsic muscles of the human eye. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye and the oth ...

function. The

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

inferior rectus Inferior may refer to: * Inferiority complex * An anatomical term of location * Inferior angle of the scapula, in the human skeleton * ''Inferior'' (book), by Angela Saini * ''The Inferior'', a 2007 novel by Peadar Ó Guilín See also *Junior (di ...

, superior oblique, 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) and ...

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, also known as a congenital disorder, 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 r ...

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

Graves Disease Graves' disease (german: Morbus Basedow), also known as toxic diffuse goiter, 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 thyro ...

(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 just one 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 form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

to localise any space occupying lesion. 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 or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples ...

Prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...

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 disabilities, parti ...

* Patching (mainly to manage amblyopia 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 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

{{Eye pathology Disorders of ocular muscles, binocular movement, accommodation and refraction