Exophthalmos
Encyclopedia
Exophthalmos is a bulging of the eye
anteriorly out of the orbit
. Exophthalmos can be either bilateral (as is often seen in Graves' disease
) or unilateral (as is often seen in an orbital tumor). Measurement of the degree of exophthalmos is performed using an exophthalmometer. Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma. Trauma to the orbit can lead to bleeding behind the eye, a condition called retrobulbar hemorrhage. The hemorrhage has nowhere to escape and the increased pressure pushes the eye out of the socket, leading to exopthalmos or proptosis and can also cause blindness if not treated promptly.
In the case of Graves' disease, the displacement of the eye is due to abnormal connective tissue deposition in the orbit and extraocular muscles which can be visualized by CT or MRI.
If left untreated, exophthalmos can cause the eyelids to fail to close during sleep leading to cornea
l dryness and damage. Another possible complication would be a form of redness or irritation called "Superior limbic keratoconjunctivitis
", where the area above the cornea becomes inflamed as a result of increased friction when blinking. The process that is causing the displacement of the eye may also compress the optic nerve
or ophthalmic artery
, leading to blindness
.
Exophthalmos is commonly found in dog
s. It is seen in brachycephalic
(short nosed) dog breeds because of the shallow orbit
. However, it can lead to keratitis
secondary to exposure of the cornea
. Exophthalmos is commonly seen in the Pug
, Boston Terrier
, Pekingese
, and Shih Tzu
.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
anteriorly out of the orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
. Exophthalmos can be either bilateral (as is often seen in Graves' disease
Graves-Basedow disease
Graves' disease is an autoimmune disease where the thyroid is overactive, producing an excessive amount of thyroid hormones...
) or unilateral (as is often seen in an orbital tumor). Measurement of the degree of exophthalmos is performed using an exophthalmometer. Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma. Trauma to the orbit can lead to bleeding behind the eye, a condition called retrobulbar hemorrhage. The hemorrhage has nowhere to escape and the increased pressure pushes the eye out of the socket, leading to exopthalmos or proptosis and can also cause blindness if not treated promptly.
In the case of Graves' disease, the displacement of the eye is due to abnormal connective tissue deposition in the orbit and extraocular muscles which can be visualized by CT or MRI.
If left untreated, exophthalmos can cause the eyelids to fail to close during sleep leading to cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
l dryness and damage. Another possible complication would be a form of redness or irritation called "Superior limbic keratoconjunctivitis
Superior limbic keratoconjunctivitis
Superior limbic keratoconjunctivitis is an ocular surface disease characterized by episodes of recurrent inflammation of the superior cornea and limbus, as well as of the superior tarsal and bulbar conjunctiva....
", where the area above the cornea becomes inflamed as a result of increased friction when blinking. The process that is causing the displacement of the eye may also compress the optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
or ophthalmic artery
Ophthalmic artery
The ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges...
, leading to blindness
Blindness
Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness...
.
Exophthalmos vs. proptosis
Some sources define exophthalmos as a protrusion of the globe greater than 18 mm and proptosis as a protusion equal to or less than 18 mm. (Epstein et al., 2003). Others define exophthalmos as protrusion secondary to endocrine dysfunction and proptosis as any non-endocrine-mediated protrusion http://www.emedicine.com/oph/topic616.htm.Causes
- LeukemiaLeukemiaLeukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
s - Orbital cellulitisOrbital cellulitisOrbital cellulitisis an infection of eye tissues posterior to the orbital septum. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood...
- MeningiomaMeningiomaThe word meningioma was first used by Harvey Cushing in 1922 to describe a tumor originating from the meninges, the membranous layers surrounding the CNS ....
, sphenoid wing - DacryoadenitisDacryoadenitis-Causes, incidence, and risk factors:Acute dacryoadenitis is most commonly due to viral or bacterial infection. Common causes include mumps, Epstein-Barr virus, staphylococcus, and gonococcus....
- MucormycosisMucormycosisZygomycosis is the broadest term to refer to infections caused by bread mold fungi of the zygomycota phylum. However, because zygomycota has been identified as polyphyletic, and is not included in modern fungal classification systems, the diseases that Zygomycosis can refer to are better called by...
- Dermoid
- Orbital fracture: apex, floor, medial wall, zygomatic
- Duane syndromeDuane syndromeDuane syndrome is a rare, congenital eye movement disorder most commonly characterized by the inability of the eye to abduct or move outwards...
- Carotid cavernous fistula
- Congenital glaucoma
- Eyelid ptosis: adult, congenital
- Nasopharyngeal angiofibromaNasopharyngeal angiofibromaNasopharyngeal angiofibroma is a histologically benign but locally aggressive vascular tumor that grows in the back of the nasal cavity. It most commonly affects adolescent males...
- Hand-Schuller-Christian diseaseHand-Schüller-Christian diseaseHand-Schüller-Christian disease is associated with multifocal Langerhans cell histiocytosis.It is associated with a triad of exophthalmos, lytic bone lesions , and diabetes insipidus ....
- HemangiomaHemangiomaA hemangioma of infancy is a benign self-involuting tumor of endothelial cells, the cells that line blood vessels. It usually appears during the first weeks of life and sometimes resolves by age 10. In more severe case hemangioma may have permanency, if not treated by a physician...
, cavernous - Thyroid ophthalmopathy (Graves' diseaseGraves' diseaseGraves' disease is an autoimmune disease where the thyroid is overactive, producing an excessive amount of thyroid hormones...
) - High altitude cerebral edemaHigh altitude cerebral edemaHigh altitude cerebral edema is a severe form of altitude sickness. HACE is the result of swelling of brain tissue from fluid leakage and almost always begins as acute mountain sickness...
(proptosis) - Beckwith–Wiedemann syndrome
- Cushing's syndromeCushing's syndromeCushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone or CRH...
(due to fat in the orbital cave) - aortic incompetence: manifests as a pulsatile pseudo proptosis, described by British cardiothoracic surgeon, Hutan Ashrafian in 2006
- Wegener's GranulomatosisWegener's granulomatosisWegener's granulomatosis , more recently granulomatosis with polyangiitis , is an incurable form of vasculitis that affects the nose, lungs, kidneys and other organs. Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression...
- Pfeiffer SyndromePfeiffer syndromePfeiffer syndrome is a rare genetic disorder characterized by the premature fusion of certain bones of the skull , which prevents further growth of the skull and affects the shape of the head and face...
Exophthalmos in dogs
Exophthalmos is commonly found in dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s. It is seen in brachycephalic
Cephalic index
Cephalic index is the ratio of the maximum width of the head multiplied by 100 divided by its maximum length ....
(short nosed) dog breeds because of the shallow orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
. However, it can lead to keratitis
Keratitis
Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...
secondary to exposure of the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
. Exophthalmos is commonly seen in the Pug
Pug
The pug is a "toy" breed of dog with a wrinkly, short-muzzled face, and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, and a compact square body with well-developed muscle. They have been described as multum in parvo , referring to the pug's personality and...
, Boston Terrier
Boston Terrier
The Boston Terrier is a breed of dog originating in the United States of America. This "American Gentleman" was accepted in 1893 by the American Kennel Club as a non-sporting breed. Color and markings are important when distinguishing this breed to the AKC standard. They should be either black,...
, Pekingese
Pekingese
The Pekingese, or "Peke" is an ancient breed of toy dog, originating in China. The breed was favored by the Chinese Imperial court, and its name refers to the city of Beijing where the Forbidden City resides...
, and Shih Tzu
Shih Tzu
The Shih Tzu is a breed of dog weighing with long silky hair. The breed originated in China and is among the earliest breeds. Shih Tzu were officially recognized by the American Kennel Club in 1969...
.
See also
- Boston's signBoston's signBoston's sign is the spasmodic lowering of the upper eyelid on downward rotation of the eye, indicating exophthalmic goiter.Similar to von Graefe's sign, it is observed in people with Graves-Basedow disease, a type of hyperthyroidism. In this disease, the immune system attacks the thyroid gland and...
- EnophthalmosEnophthalmosEnophthalmos is the recession of the eyeball within the orbit.It may be a congenital anomaly, or be acquired as a result of trauma , Horner's syndrome, silent sinus syndrome, or phthisis bulbi....
- Marty FeldmanMarty FeldmanMartin Alan "Marty" Feldman was an English comedy writer, comedian and actor who starred in a series of British television comedy shows, including At Last the 1948 Show, and Marty, which won two BAFTA awards and was the first Saturn Award winner for Best Supporting Actor for his role in Young...
- Von Graefe's signVon Graefe's signVon Graefe's sign is the immobility or lagging of the upper eyelid on downward rotation of the eye, indicating exophthalmic goiter ....
- Graves ophthalmopathy
- HeinoHeinoHeino is a German singer of popular music and traditional Volksmusik....