Exophthalmos (also called exophthalmus, exophthalmia, proptosis, or exorbitism) is a bulging of the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

anteriorly out of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. Exophthalmos can be either bilateral (as is often seen 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 thyr ...

) or unilateral (as is often seen in an orbital tumor). Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma. In the case of Graves' disease, the displacement of the eye results from abnormal connective tissue deposition in the orbit and

extraocular muscles 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 ot ...

, which can be visualized by CT or

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 ...

. If left untreated, exophthalmos can cause the eyelids to fail to close during sleep, leading to

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...

l dryness and damage. Another possible complication is a form of redness or irritation called

superior limbic keratoconjunctivitis Superior limbic keratoconjunctivitis (SLK, Théodore's syndrome) is a disease of the eye characterized by episodes of recurrent inflammation of the superior cornea and limbus, as well as of the superior tarsal and bulbar conjunctiva. It was first ...

, in which 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 In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

ophthalmic artery The ophthalmic artery (OA) is an artery of the head. It is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some st ...

, and lead to

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

Causes

Inflammatory/Infection: *

Graves' ophthalmopathy Graves’ ophthalmopathy, also known as thyroid eye disease (TED), is an autoimmune inflammatory disorder of the orbit and periorbital tissues, characterized by upper eyelid retraction, lid lag, swelling, redness (erythema), conjunctivitis, and b ...

due to

, usually causes bilateral proptosis. *

Orbital cellulitis Orbital cellulitis is inflammation of eye tissues behind the orbital septum. It is most commonly caused by an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. It may also occur after trauma. W ...

– often with unilateral proptosis, severe redness, and moderate to severe pain,

sinusitis Sinusitis, also known as rhinosinusitis, is inflammation of the nasal mucosa, mucous membranes that line the paranasal sinuses, sinuses resulting in symptoms that may include thick Mucus#Respiratory system, nasal mucus, a nasal congestion, plugg ...

and an elevated white blood cell count. *

Dacryoadenitis Dacryoadenitis is inflammation of the lacrimal glands. Symptoms * Swelling of the outer portion of the upper lid, with possible redness and tenderness * Pain in the area of swelling * Excess tearing or discharge * Swelling of lymph nodes in fro ...

Erdheim–Chester disease Erdheim–Chester disease (ECD) is an extremely rare disease characterized by the abnormal multiplication of a specific type of white blood cells called histiocytes, or tissue macrophages (technically, this disease is termed a non- Langerhans-cel ...

Mucormycosis Mucormycosis, also known as black fungus, is a serious fungal infection that comes under fulminant fungal sinusitis, usually in people who are immunocompromised. It is curable only when diagnosed early. Symptoms depend on where in the body the ...

* Orbital pseudotumor – presents with acute, usually unilateral proptosis with severe pain. *

High-altitude cerebral edema High-altitude cerebral edema (HACE) is a medical condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves di ...

Granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...

Neoplastic: *

Leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ' ...

s *

Meningioma Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing o ...

, (of sphenoid wing) *

Nasopharyngeal angiofibroma Nasopharyngeal angiofibroma is an angiofibroma also known as juvenile nasal angiofibroma, fibromatous hamartoma, and angiofibromatous hamartoma of the nasal cavity. It is a histologically benign but locally aggressive vascular tumor of the nasophar ...

Hand–Schüller–Christian disease Chronic multifocal Langerhans cell histiocytosis, previously known as Hand–Schüller–Christian disease, is a type of Langerhans cell histiocytosis (LCH), which can affect multiple organs. The condition is traditionally associated with a combina ...

Hemangioma A hemangioma or haemangioma is a usually benign vascular tumor derived from blood vessel cell types. The most common form, seen in infants, is an infantile hemangioma, known colloquially as a "strawberry mark", most commonly presenting on the ski ...

, cavernous Cystic: *

Dermoid cyst A dermoid cyst is a teratoma of a cystic nature that contains an array of developmentally mature, solid tissues. It frequently consists of skin, hair follicles, and sweat glands, while other commonly found components include clumps of long hair, ...

Vascular: *

Carotid-cavernous fistula A carotid-cavernous fistula results from an abnormal communication between the arterial and venous systems within the cavernous sinus in the skull. It is a type of arteriovenous fistula. As arterial blood under high pressure enters the cavernous s ...

Aortic insufficiency Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a conseq ...

: manifests as a pulsatile pseudoproptosis, described by British cardiothoracic surgeon Hutan Ashrafian in 2006 Others: *

Orbital fracture Facial trauma, also called maxillofacial trauma, is any physical trauma to the face. Facial trauma can involve soft tissue injuries such as burns, lacerations and bruises, or fractures of the facial bones such as nasal fractures and fractures ...

: apex, floor, medial wall, zygomatic *

Retrobulbar hemorrhage Retrobulbar bleeding, also known as retrobulbar hemorrhage, is when bleeding occurs behind the eye. Symptoms may include pain, bruising around the eye, the eye bulging outwards, vomiting, and vision loss. Retrobulbar bleeding can occur as a r ...

: trauma to the orbit can lead to bleeding behind the eye. The hemorrhage has nowhere to escape and the increased pressure pushes the eye out of the socket, leading to proptosis and can also cause blindness if not treated promptly. *

Cushing's syndrome Cushing's syndrome is a collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol. Signs and symptoms may include high blood pressure, abdominal obesity but with thin arms and legs, reddish stretch marks, ...

(due to fat in the orbital cave) * Some forms of

craniosynostosis Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...

: **

Crouzon syndrome Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Since the branchial ...

Pfeiffer syndrome Pfeiffer syndrome is a rare genetic disorder characterized by the premature fusion of certain bones of the skull (craniosynostosis) which affects the shape of the head and face. In addition, the syndrome includes abnormalities of the hands (such ...

** Pansynostosis

Anatomy

Proptosis is the anterior displacement of the eye from the orbit. Since the orbit is closed off posteriorly, medially and laterally, any enlargement of structures located within will cause the anterior displacement of the eye. Swelling or enlargement of the lacrimal gland causes inferior medial and anterior dislocation of the eye. This is because the lacrimal glands are located superiorly and laterally in the orbit.

Diagnosis

Measurement

Measurement of the degree of exophthalmos is performed using an exophthalmometer. Most sources define exophthalmos/proptosis as a protrusion of the globe greater than 18 mm. The term exophthalmos is often used when describing proptosis associated with

Animals

Exophthalmos is commonly found in

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...

s. It is seen in

brachycephalic Brachycephaly (derived from the Ancient Greek '' βραχύς'', 'short' and '' κεφαλή'', 'head') is the shape of a skull shorter than typical for its species. It is perceived as a desirable trait in some domesticated dog and cat breeds, ...

(short-nosed) dog breeds because of the shallow

. It can lead to

keratitis Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired e ...

secondary to exposure of the

. Exophthalmos is commonly seen in the

pug The Pug is a breed of dog originally from China, with physically distinctive features of a wrinkly, short-muzzled face and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, most often light brown (fawn) or blac ...

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 f ...

Pekingese The Pekingese (also spelled Pekinese) is a breed of toy dog, originating in China. The breed was favored by royalty of the Chinese Imperial court as a companion dog, and its name refers to the city of Peking (Beijing) where the Forbidden City i ...

, and

shih tzu The Shih Tzu (, ; literally " Hsi Shih dog") is a toy dog breed originating from Tibet and was bred from the Pekingese and the Lhasa Apso. Shih Tzus are known for their short snouts and large round eyes, as well as their long coat, floppy ear ...

. It is a common result of

head trauma A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...

and pressure exerted on the front of the neck too hard in dogs. In cats, eye proptosis is uncommon and is often accompanied by facial fractures. About 40% of proptosed eyes retain vision after being replaced in the

, but in cats very few retain vision. Replacement of the eye requires general

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), ...

. The eyelids are pulled outward, and the eye is gently pushed back into place. The eyelids are sewn together in a procedure known as

tarsorrhaphy Tarsorrhaphy is a surgical procedure in which the eyelids are partially sewn together to narrow the eyelid opening. It may be done to protect the cornea in cases of corneal exposure, as a treatment for Graves' ophthalmopathy, Möbius syndrome or ...

for about five days to keep the eye in place. Replaced eyes have a higher rate of

keratoconjunctivitis sicca Dry eye syndrome (DES), also known as keratoconjunctivitis sicca (KCS), is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge, and easily fatigued eyes. Blurred vision may also occur. Symptoms range ...

and

and often require lifelong treatment. If the damage is severe, the eye is removed in a relatively simple

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

known as

enucleation of the eye Enucleation is the removal of the eye that leaves the eye muscles and remaining orbital contents intact. This type of ocular surgery is indicated for a number of ocular tumors, in eyes that have sustained severe trauma, and in eyes that are other ...

. The

prognosis Prognosis (Greek: πρόγνωσις "fore-knowing, foreseeing") is a medical term for predicting the likely or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) or remain stabl ...

for a replaced eye is determined by the extent of damage to the

and

sclera The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and som ...

, the presence or absence of a

pupillary light reflex The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, there ...

, and the presence of ruptured rectus muscles. The rectus muscles normally help hold the eye in place and direct eye movement. Rupture of more than two rectus muscles usually requires the eye to be removed, because significant blood vessel and nerve damage also usually occurs. Compared to brachycephalic breeds, dochilocephalic (long-nosed) breeds usually have more trauma to the eye and its surrounding structures, so the prognosis is worse.

References

External links

{{Eye pathology Dog diseases Disorders of eyelid, lacrimal system and orbit