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Module 49: The Orbit Home Contact Us Exam Prep Courses How to Career Corner Tools for Administators Home Module 49: The Orbit | print | Module 49: The Orbit LOGIN Hi, jeweitz08 Logout GO TO: Home Introduction Course Catalog My Courses My CE Credits Change user details FAQs / Help Contact Us TECH TIPS Quarterly Tech Tips ✔ E-letter Contents: Anatomy Regions of the orbits Openings on the orbits Sinuses Imaging of the orbits X-ray CT scan MRI Ultrasonography Diseases of the orbital region Orbital cellulitis Idiopathic orbital inflammation Vasculitis Tumors History Taking Clinical Examination Proptosis (exophthalmos) Name Anatomy E-mail The bony orbit provides protection for the eyeball and a place to hang out (so to http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Receive Text HTML Subscribe speak). The orbit is shaped roughly like a pyramid, with the base of the pyramid at the front (on the face) and the apex in the back (toward the brain). The orbit is lined by fatty tissue, which provides lubrication for movement within the orbit. The eyeball is suspended by the extraocular muscles within the orbit. The model below gives us an idea of the structure. Move your mouse over the image to remove the globe and some of the extraocular muscle structure. Merchant Services Figure 49-1 - Legal Stuff *These courses are not spon by JCAHPO® ; only reviewed compliance with JCAHPO® standards and criteria and aw continuing education credit accordingly; therefore, JCAH cannot predict the effectivene the program or assure its qua substance and presentation. JCAHPO® , COA ® , COT ® , a COMT ® are registered trade the Joint Commission on Allie Health Personnel in Ophthalm Copyright © 1998-2012 eye There are four basic regions to the orbit: the roof, the floor, the medial wall, and the temporal wall. There are 7 bones that make up the orbit. Unfortunately for test takers, the bones are not nicely divided into regions. As shown on the schematic below, the orbital bones connect together like a puzzle. The 7 bones are as follows, and are identified on the schematic by colors and their first letters. Move your mouse over the schematic to view an orientation photo. frontal Terms and Conditions Pr maxilla Policy zygoma Eyetec.net is a division of T sphenoid Publishing LLC All rights ethmoid reserved. No part of this site lacrimal reproduced, stored, or transm any form or by any means wi the written permission of the palantine The white circle on the schematic indicates the location of the orbital rim. Notice publisher except for brief http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit that the sphenoid bone (green) has two "wings", the greater wing and the lesser wing. The hole (black) in the lesser wing is the optic foramen, through which the optic nerve and the ophthalmic artery pass. The space (black) between the two wings of the sphenoid is the superior orbital fissure, through which pass cranial nerves III, IV, V, and VI. quotations. Figure 49-2 The regions of the orbit are all made up of one or more of the orbital bones: The floor - Three bones make up the floor: the maxilla (or maxillary), the zygoma (or zygomatic), and the palantine. The maxillary bone occupies the most space on the floor. The orbital floor is the weakest region of the orbit. A concussive force, such as a fist to the eye, can fracture the orbit floor and entrap the inferior rectus muscle. The is called a blow-out fracture. A blowout fracture is characterized by a history of concussive trauma, swelling of the soft tissues of the orbit, and the inability of the eye to look upward due to the entrapped inferior rectus muscle. Fortunately, most blow-out fractures resolve without the need for surgery. When the swelling goes down, the muscle usually becomes free. The roof - The frontal bone forms the roof of the orbit. The medial wall - Four bones make up the medial wall of the orbit: the maxilla, lacrimal, ethmoid, and sphenoid (lesser wing) bones. The lateral wall - The zygomatic bone makes up the anterior lateral wall, and http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit the greater wing of the sphenoid bone makes up the posterior lateral wall. The zygoma is also part of the jaw. Openings in the orbit Optic foramen (or optic canal) - The optic nerve enters the eye through the optic foramen, which is a hole at the apex (back) of the orbit. If you observe the upper left corner of the image in Figure 49-1 while moving the mouse pointer over the image, you can see how the nerve fits through this hole. Orbital fissures - The superior and inferior orbital fissures are "cracks" at the back of the orbit. These are shown as black areas in the center of Figure 492. Cranial nerves III, IV, V, and VI, and the superior ophthalmic vein pass through the superior fissure. The inferior ophthalmic vein passes through the inferior fissure. Supraorbital foramen - There is a hole at the top of the orbit which is called the superorbital foramen, which is more like a notch located just under the eyebrow. The supraorbital nerve, the supraorbital artery, and the supraorbital vein pass through this notch. Infraorbital foramen - This is a hole in the high cheek area through which pass the infraorbital nerve, the infraorbital artery, and the infraorbital vein. http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Sinuses The paranasal sinuses are air filled spaces within the bones of the face. The spaces open into the nasal cavity and they surround the orbit except on the temporal side. In the x-ray image below, the orbits are identified with the letter "O", the maxillary sinuses are labeled with "M", and the ethmoid sinuses are labeled with "E". Sphenoid and frontal sinuses are not shown. Inflammation, blockage, and drainage of the sinuses are commonly associated with allergies and colds. http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Imaging of the Orbits Abnormalities of the orbits occur from congenital defects, inflammation, trauma, and tumors. There are a variety of imaging modalities that the physician can use to evaluate the orbital regions: X-ray Computerized Axial Tomography (CT scan) Magnetic Resonance Imaging (MRI) Ultrasonography X-ray Imaging An X-ray is a form of radiation. X-ray imaging involves sending a small burst of x-ray radiation through the body. Xrays are absorbed by varying degrees by parts of the body. The radiation is absorbed to a high degree by bones, to a lesser degree by soft tissues, and not at all by air spaces. The X-rays that pass through the body are captured on special imaging plates (it used to be film). Since bones absorb a greater degree of the radiation, the image of http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit bones will appear whitish. Air spaces will appear black, and soft tissue will appear as shades of gray. X-rays provide information about the integrity of bony structures in cases of trauma, and x-rays are good at imaging highly x-ray opaque objects such as the metallic foreign body imaged below by x-ray. X-rays are not sensitive enough to image small fractures. X-rays are not particularly good for imaging soft tissues. Single X-rays are not used much anymore for orbital evaluation, having been replaced by the CT Scan, which http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit creates multiple X-ray cuts. CT Scan (CAT scan) "CT" stands for computed tomography. Sometimes it is referred to as "Computerized Axial Tomography" (CAT) scanning. Tomography means "to image by slicing". The CT scanner takes a number of X-ray "slices" of the body which are then joined together by computer into cross-sectional and 3-D views of the body. The CT scan provides greater image resolution compared to conventional X-ray imaging. Small fractures and soft tissue are imaged in more detail with a CT scan compared to conventional X-ray imaging. Below is an image of the orbits taken with a CT scanner. Magnetic Resonance Imaging (MRI) MRI uses a magnetic field, radio waves, and a computer to produce images of the internal structures of the body. No radiation is used. Currently http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit MRI provides the most detailed images of the structures inside the head. In order to obtain good quality images, the patient must hold very still. MR imaging is more expensive than CT scanning, it takes more time, and the results may not be immediately available. These factors make CT scanning more practical in trauma cases. The MRI may adversely affect the function of a medical device (such as a pacemaker). The MRI may cause a metallic material in the body to move and/or heat up. The image below gives you an idea of the fantastic detail that MRI can provide. Costs vary widely, but to give you an idea an X-ray of the orbits may cost as little as $40, a CT scan about $200, and an MRI about $400. http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Ultrasonography Ultrasonography uses sound waves to image the globe and, to a limited extent, the orbits. It is most useful for the ophthalmologist as a tool to image inside the globe when no view of the vitreous and/or the retina is available, usually due to a dense cataract or a vitreous hemorrhage. It is less useful as an imaging device for the orbital area. The ultrasound is useful as a screening device for orbital disease. CT scanning and MRI provide more detailed imaging of the orbit. Below is an ultrasound image of a mucocele of the frontal sinus (M). The vitreous inside the globe is the black (low reflective) area labeled with the "V". Orbital fat is highly reflective of the ultrasound beam and the fat is visible as the white area. Diseases of the Orbital Region This discussion is not meant to be a comprehensive study of orbital diseases. It is not even a complete listing of orbital diseases. The goal is to familiarize you with http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit some of the terminology of orbital diseases. Diseases of the orbital region include orbital cellulitis, idiopathic orbital inflammation, thyroid orbitopathy (Graves disease), vasculitis, and a variety of tumors. Orbital cellulitis is the most common cause of proptosis in childhood. The source of infection is usually a paranasal sinusitis. The patient presents with swelling of the orbital soft tissues, pain, and fever. There is usually restricted eye movement and there may be decreased vision. Complications can be serious with up to 11% of cases resulting in vision loss. Treatment includes hospitalization with the administration of an appropriate intravenous antibiotic. Surgical drainage of an abscess is sometime required. Idiopathic orbital inflammation can be acute or chronic, and it can involve frequent relapses. "Idiopathic" means "of unknown cause". It can be unilateral or bilateral, and it can involve any of the orbital tissues. Symptoms can include pain, swelling, proptosis, limited eye movement, and vision loss. Tissue biopsy reveals fibrosis of the tissue with infiltration of lymphocytes, plasma cells, and eosinophils. Treatment involves systemic steroids, and may include radiation or orbital decompression. Thyroid orbitopathy (Grave's disease) is the most common cause of proptosis in adults. The age of onset is usually 20 to 45 years old. It affects 8x more women than men. It is a systemic disease with most cases due to hyperthyroid. Clinical symptoms can include exophthalmos, eyelid retraction, lid lag, lagophthalmos (the lids cannot close completely), diplopia due to restricted muscle movement, edema of the eyelid, and swelling of the conjunctiva (chemosis). The optic nerve can be damaged due to excessive pressure on the nerve (compressive optic neuropathy). Symptoms are caused by enlargement of the extra-ocular muscles due to infiltration. Non-surgical treatment may include lubrication of the eyeball and systemic prednisone. Surgical treatments may include orbital decompression, EOM surgery, and lid retraction repair. Radiation may be used for refractory (unresponsive to treatment) cases. http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Above: Exophthalmos, and eyelid retraction secondary to thyroid orbitopathy. Above: CT scan showing exophthalmos and enlarged extraocular muscles, particularly the medial rectus muscles (arrows). Vasculitis of the orbital region includes giant cell arteritis. Giant cell arteritis (GCA) is an inflammation of the lining of the artery. It most often affects the arteries in the head, especially the temples. It is sometimes called temporal arteritis. The average age of onset is 70, and it rarely occurs in people below the age of 50. It affects twice as many women as men, and the vast majority are white. About half the people with GCA also have polymyalgia rheumatica (an arthritic condition). Symptoms can include head pain, especially tenderness at the temples, double vision, decreased vision, jaw pain, fever, and pain and stiffness in the neck, arms and hips. The condition can cause an aneurysm, stroke, or blindness. Blindness results from decreased blood flow to the eye. The condition is treated with high dose steroids. Tumors of the orbital region include developmental pediatric tumors, metastatic pediatric tumors, metastatic adult tumors, vascular tumors, neural tumors, lacrimal gland tumors, lymphoproliferative lesions, mesenchymal tumors, and secondary orbital tumors. Specific tumors in each category are listed below. You should read each name so that you become familiar with the terminology. Do an internet search on the term if you are interested in more information. http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Developmental pediatric tumors include the following: dermoid cyst lipodermoid teratoma Metastatic pediatric tumors include: neuroblastoma leukemia Mesenchymal tumors include: rhabdomyosarcoma (most common primary orbital malignancy in children) Metastatic adult tumors of the orbit are rare. A metastatic tumor is a tumor that has spread from another source. Intraocular metastases are ten times more common. The most common source of metastatic tumors for women is breast cancer. The most common source for men is lung cancer. Vascular tumors include the following: capillary hemangioma lymphangioma cavernous hemangioma (this is the most common benign orbital tumor in adults) hemangiopericytoma AV malformation AV fistula Varices http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit Neural tumors include the following: optic nerve glioma meningioma neurofibromatosis neurofibroma schwannoma (neurilemmoma) Lacrimal gland tumors include the following: pleiomorphic adenoma adenoid cystic carcinoma nonepithelial (infiltrative) lesions Lymphoproliferative lesions include: lymphoid hyperplasia malignant lymphoma Secondary orbital tumors include: sinus tumors (mucocele, carcinoma) eyelid tumors intraocular tumors with orbital extension History taking related to orbital disease As related to orbital disease, the following considerations are of particular importance: Is this the first time the patient has seen a doctor? Was the patient referred by another doctor (get details)? If seen by another doctor, where there http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit diagnostic studies done? If so, how can the studies be obtained? If a diagnosis has been made, what is the diagnosis? How long has the patient had the problem (hours, days, weeks, months, years)? Has there been trauma associated with the condition? If so, what are the details? Has there been any other physical condition or sickness recently? Is there pain associated with the condition? If so, how intense? Where is the pain located? Is it constant, or does it come and go? Has it been staying the same, getting better, or getting worse? Does anything relieve the pain? Is the pain worse in certain circumstances? Is the patient taking pain medication? Does the medication help? Has the patient's vision been affected? To what degree? Is it getting better or worse? When did the patient first notice a vision problem? Does the patient have double vision? If so, when did it start? Is there double vision only when looking in a particular direction? Has there been a change in appearance? If so, how has it changed and when did it change? The clinical exam for orbital disease The clinical exam may involve a complete eye exam with dilation, if this has not recently been done. Specific to orbital disease, the physician will be examining the area around the globe for "periorbital" changes. The conjunctiva will be examined for changes in coloration, lesions, swelling, and unusual blood vessel formations. The lids will be examined for lesions, retraction, swelling, and unusual formations. The skin will be examined for ecchymosis, other discolorations, lesions, swelling, and unusual formations. Eccymosis is a purplish discoloration of the skin caused by blood that escapes from blood vessels under the skin (a bruise from trauma is an example). The physician my examine by palpation, using his fingers to feel for abnormal structures in the periorbital area. Palpation can also be used to gently push the globe toward the back of the socket (retrodisplacement) to detect resistance to movement which may mean that there is an obstruction behind the globe. The physician will observe and sometimes palpate for pulsation of blood vessels, http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit which may indicate high blood flow in a vascular lesion. The doctor may also listen for bruits (rhymes with Louie), which is an abnormal blowing sound over a peripheral blood vessel, which can be an indicator of a fistula. A fistula is an abnormal passageway between two organs. Proptosis (exophthalmos) The physician will also be looking for, and sometimes measuring, proptosis. The short definition of proptosis is abnormal protrusion of the eyeball. The terms exophthalmos and proptosis are often used interchangeably. Some use exophthalmos to mean abnormal protrusion secondary to Grave's disease and proptosis to mean abnormal protrusion secondary to any other cause (e.g. a tumor). Proptosis is measured from the bony orbital rim to the apex of the cornea: Normal has been defined as protrusion in the 16 to 20mm range, although exophthalmos and proptosis are sometimes defined to be protrusion greater than 18mm. In the clinical situation, the definition is not of much importance unless the measurement is significantly greater than 20. On the first visit, the doctor may want to get a baseline measurement which is subsequently compared to measurements on future visits in order to monitor change over time. The patient with significant proptosis does not need a measurement for confirmation of the condition, the obvious 'bug eyed" appearance speaks for itself. Proptosis can be monocular or binocular. Exophthalmos from Grave's disease is usually bilateral. Proptosis from an orbital tumor is usually monocular. The globe can be displaced straight out (axial proptosis) or it can be displaced in non-axial directions. Axial displacement occurs from diffuse enlargement of the orbital soft tissues and/or EOMs, or from a lesion in the orbital cone (directly behind the globe). Non-axial displacement occurs when the globe is pushed away from the http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit sight of a lesion. For example, a downward/medial displacement can occur in the presence of a lacrimal gland tumor. The doctor must differentiate between true proptosis and pseudoproptosis. Very nearsighted eyes (long axial length) can appear to be proptotic. A fellow eye can falsely appear to be proptotic when the other eye is "sunken in" perhaps due to enophthalmos, an orbital bone asymmetry post trauma, or a palebral fissure asymmetry. The ophthalmic assistant or technician can be assistance with the orbital eye exam by measuring eye protrusion with the exophthalmometer. For a discussion on the use of this instrument, see Module 29, Section 5. Back to top http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM] Module 49: The Orbit http://www.eyetec.net/index.php?option=com_content&view=article&id=285[4/21/2013 8:50:59 AM]