Neuro-Ophthalmic Disorders: When is it an Emergency? Patricia A. Modica, OD; FAAO Joseph Sowka, OD, FAAO, Dipl. Topic 1

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1 1 Neuro-Ophthalmic Disorders: When is it an Emergency? Patricia A. Modica, OD; FAAO Joseph Sowka, OD, FAAO, Dipl Topic 1 Cranial Nerve III Palsy: Is this CN III palsy? Is this an isolated CN III palsy? If this is an isolated CN III palsy, what is the work-up? CN III Anatomy: CN III is the only CN with a sub-nuclear complex Medial rectus (MR), inferior rectus (IR), superior rectus (SR-decussates with contralateral innervation), inferior oblique (IO), levator (bilateral upper lid) Paired sub-nuclei with decussation of one sub-nuclei One unpaired sub-nuclei controls both eyelids Arises in the midbrain (mesencephalon) at the level of the superior colliculus Breaks into a superior and inferior division Pupillomotor fibers travel with the inferior division and the inferior oblique CN III Palsy: Clinical Picture Eye that is down and out with a ptosis Pupil features Pupil may be dilated (involved) or normal (spared) Variations Palsy is complete; paresis is incomplete Signature motility of CN III palsy: A hyper deviation that increases in up gaze, reverses in down gaze Exo deviation which increases in opposite gaze Other possibilities Remember the possibility of a partial paresis or isolated muscle paresis. Isolated muscle paresis are in the orbit, nerve nucleus, or neuromuscular junction (myasthenia gravis) Nuclear CN III palsy cannot exist without contralateral involvement (contralateral ptosis and SR weakness) CN III: Anatomic Course Fascicles pass through parenchyma of midbrain through Red Nucleus and Corticospinal Tract A lesion, which involves the CN III fascicles as they pass through the Red Nucleus, will cause CN III palsy with a contralateral intention tremor and ataxic gate. This is termed Benedickt s syndrome.

2 2 A lesion which involves the CN III fascicles as they pass through the Corticospinal tract will result in a CN IIII palsy with a contralateral hemiplegia. This is termed Weber s syndrome. Exits midbrain into subarachnoid space between cerebral peduncles between superior cerebellar artery and posterior cerebral artery and follows posterior communicating artery Enters the lateral wall of cavernous sinus where it bifurcates into superior and inferior divisions just before exiting cavernous sinus Enters the superior orbital fissure where it further divides to innervate the individual muscles CN III is vulnerable to compression by aneurysm along course of posterior communicating artery or at tip of basilar artery Pupillomotor fibers are peripheral in nerve and prone to compression, but relatively immune to ischemia CN III Palsy: Still More Clues A dilated pupil means compression by aneurysm (emergency!) A sudden onset CN III palsy with a dilated, poorly responsive pupil is most likely to be caused by an aneurysm Pain can mean anything Aneurysms are always painful Boring pain Ischemic vascular infarct is painful 90% Retro-orbital pain A spared pupil does not always rule out aneurysm There have been 7 cases reported where the pupil was initially uninvolved, but the etiology was an aneurysm. Most of these cases were partial CN III palsies that worsened and became pupil involving over 1 week. Watch these patients daily over one week. Never dilate CN III palsy An involved pupil does not rule out ischemia In extreme infarcts, the pupil may be involved as well. These cases are in older patients with vascular disease and are complete CN III palsies In a patient with a paresis (incomplete palsy), you can not call the pupil There is likely an incipient aneurysm growing. A spared pupil does not rule out a life-threatening emergency here. When is it an Emergency? CN III palsy caused by aneurysm 20% die within 48 hrs from rupture 50% overall die Average time from onset to rupture 29 days 80% rupture w/i 29 days Many never make it to hospital Ruptured aneurysms 5% surgical mortality

3 3 60% functional impairment post-op Unruptured aneurysms No mortality; 75% with normal outcomes; 50% with CN III recovery Pupil involved CN III palsy = aneurysm of PCA until proven otherwise Complete external dysfunction CN III palsy with normal pupil (pupil spared) is not likely to be an aneurysm & is likely to be vasculopathic ischemic palsy that will resolve with observation alone Partial internal dysfunction (relative pupil sparing, anisocoria but reactive pupil) = intermediate but unknown risk of aneurysm Dilated pupil alone (internal dysfunction but no external dysfunction) is NOT a CN III palsy Isolated dilated pupil in an ambulatory patient (with no ocular motility deficits) is not an aneurysm, but much more likely to be from iris trauma, medication/ pharmacologic dilation, or tonic pupil Imaging of CN III palsy Digital subtraction angiography is gold standard and should be done when aneurysm highly suspected CT/CTA is preferred non-invasive imaging for CN III palsy CT to identify subarachnoid hemorrhage (SAH) CTA requires contrast- renal impairment prefers MRI/MRA CTA superior to MRI when patient can t have MRI Pacemaker, claustrophobia MRI superior for non-aneurysmal causes (tumor) MRA adds very little time to scan Causes of CN III Palsy: ADULTS CHILDREN Undetermined (24%) Congenital (44%) Aneurysm (21%) Trauma (16%) Ischemia (18%) Inflammation (11%) Trauma (13%) Miscellaneous (11%) Neoplasm (12%) Neoplasm (10%) Miscellaneous (12%) Aneurysm or ischemia (6%) CN III Palsy: Aberrant Regeneration When damage to the CN III results in a resprouting and miscommunication of nerves to muscles Inferior rectus and medial rectus communicates with levator Medial rectus communicates with pupil Clinical picture: Patient looks medial: lid elevates Patient looks lateral: lid lowers

4 4 Patient looks down: lid elevates (Pseudo-Von Graefe s). This typically is the most identifiable sign in primary or secondary aberrant regeneration Patient looks medial: pupil constricts CN III Palsy: Two Types of Aberrant Regeneration: Primary: Occurs independent of antecedent CN III Palsy. Caused by aneurysm or meningioma within cavernous sinus Secondary: Occurs after an antecedent CN III palsy. Causes: Aneurysm within subarachnoid space, trauma, tumor, inflammation NEVER DIABETES! If cause of CN III palsy is determined to be ischemic vascular (diabetes, HTN, etc.) and then the eye undergoes aberrant regeneration, the initial diagnosis is wrong. You must re-examine for tumor or aneurysm within ipsilateral cavernous sinus. Topic 2 Myasthenia Gravis Myasthenia Gravis is an auto-immune disorder in which antibodies attach near acetylcholine receptors to block neuro-muscular transmission. Important Features: Neuromuscular disorder Muscle Weakness/Fatigability Affects voluntary muscle (particularly that which is innervated by cranial nerves) Muscle weakness seen in myasthenia gravis may be subtle or obvious and has a variable magnitude (increases with muscle fatigue). Ocular Involvement Levator--results in ptosis EOMs--diplopia and characteristic motility patterns Orbicularis Oculi--incomplete closure and weakness to forced closure In-Office Diagnostic Testing Sleep Test o After a short nap (30 minutes) myasthenics will show improvement in their motility pattern. Ice-pack Test o Cold temperatures inhibit the action of acetylcholinesterase thereby reducing the fatigue seen in myasthenia. An ice-pack held on the eyelids for five minutes may eliminate a ptosis caused by myasthenia. Myasthenia Work-Up 1. Lab Studies--diagnostic and to rule out other auto-immune disorders Acetylcholine receptor antibodies (found in 50% of OMG)

5 5 Thyroid Function Tests Rule out Graves' Disease 2. Tensilon Test diagnostic Ptosis tends to respond better False positives are common Prostigmine is used in kids Side effects rare but serious Sleep test is an in-office alternative Ocular Management Prism Patching Eyelid Tape Medical Management Cholinesterase Inhibitors (Mestinon, Prostigmine) Immunosuppressives (corticosteroids, cyclosporin) Cytotoxic Agents (Azothioprine) Thymectomy Ocular vs. Generalized MG When the neuro-muscular weakness is confined to the ocular muscles noted previously, it is termed Ocular Myasthenia Gravis or OMG. When the weakness extends to other muscle groups in the body, we refer to it as generalized myasthenia gravis. Since myasthenia gravis has a predilection for muscles innervated by cranial nerves, we will often observe the following in patients with generalized disease: Loss of facial expression (myasthenic snarl) Nasal regurgitation of liquids, choking on foods and difficulty swallowing Slurred speech and hoarseness Respiratory difficulty In addition, proximal muscles are affected more so than distal muscles so these patients might report difficulty combing hair, lifting heavy objects, getting up from a chair, climbing stairs, walking. When is it an emergency? Myasthenic Crisis Occurs when weakness affect the muscles that control breathing. This constitutes a medical emergency that requires a respirator to assist in breathing. All myasthenic patients should be questioned about the prevalence of dyspnea on fullow-up visits with emergency referral if myasthenic crisis is suspected. Topic 3

6 6 Anterior Ischemic Optic Neuropathy Anterior ischemic optic neuropathy (AION) is an ischemic, non-inflammatory condition involving the optic nerve head and retro-laminar portions of the optic nerve Clinical Presentation Acute vision loss that ranges from mild to severe Optic nerve swelling with flame hemorrhages, arteriole attenuation and NFL infarcts Optic nerve dysfunction Visual field defects Optic Nerve Appearance Swelling that may be focal or circumferential. In more severe cases it is a more pallid swelling Arterial attenuation Flame hems NFL infarcts; especially with severe ischemia Macular star Visual Field Loss Altitudinal 62% Inferior 47% Superior 15% Central scotoma 21% Inferior quad 7% Inf arcuate 8% Pathogenesis AION results from hypoperfusion of the posterior ciliary arterial supply to the anterior optic nerve head. Mechanical factors and atherosclerotic disease play a role in the non-arteritic form while vasculitis contributes in the arteritic form. Hayreh has demonstrated that nocturnal drops in blood pressure play a significant role in pathogenesis. Normal nocturnal dips in BP result in diminished perfusion pressure to distal tissues supplied by smaller blood vessels. In fact, patients with non-arteritic AION are more likely to notice their vision loss upon awakening because they have hyperperfused their optic nerves during sleep. Patients who take antihypertensive medications have the most significant drops in nocturnal BP, particularly if they take their medications in the evening.

7 7 Risk Factors 1. Hypertension 2. Diabetes 3. Atherosclerotic disease 4. Small optic nerves 5. Giant cell arteritis* *The first four are risk factors for the non-arteritic form while the fifth is a risk factor for the arteritic form. Additional non-arteritic risk factors include ischemic heart disease, elevated cholesterol, and sleep apnea. NAAION and phosphodiesterase type 5 inhibitors The Viagra Connection Risk of AION is controversial; it is a commonly used drug and the involved population likely has risk factors to begin with. Proposed mechanisms included decreased optic nerve perfusion secondary to systemic arterial hypotension and altered autoregulation of blood flow to the optic nerve head. At this time, patients who have a history of NAION in one eye should probably avoid phosphodiesterase type 5 inhibitors. When is it an Emergency? When giant cell arteritis is suspected, AION becomes an emergency due to the high risk of involving the fellow eye within a short period of time. Laboratory testing followed by temporal artery biopsy is necessary to confirm the diagnosis, however, a careful assessment of the clinical presentation can be very helpful in getting a handle on the likelihood of GCA. Arteritic Symptoms Scalp tenderness Jaw claudication Mild fever Arthralgias; myalgias In addition to arteritic symptoms, there are a number of clinical characteristics that can be helpful in distinguishing arteritic from non-arteritic AION: Arteritic AION occurs in an older (70+) age group than non-arteritic (55+) Visual loss and visual field defects are typically devastating in arteritic AION and mild to moderate in non-arteritic AION Hypertension, diabetes, atherosclerotic disease and small nerves do not play a direct role in arteritic AION Nerve fiber layer infarcts and more pallid swelling occur more often in arteritic AION Arteritic AION is often preceded by episodes of transient vision loss

8 8 Visual Prognosis Most patients with non-arteritic disease have stable vision loss although a small subset will have some improvement and another small subset will show some deterioration Prognosis is poor for arteritic forms, even when treated. Fellow eye can be affected within 24 hours. Management 1. Rule out GCA Careful history ESR; C-reactive protein Temporal artery biopsy 2. Rule out systemic disease Hypertension, diabetes and other disorders that increase risk of vascular compromise 3. Appropriate information should be communicated with the patient s physician. If your level of clinical suspicion for GCA is high, this is considered an ocular emergency and the patient needs to be started on corticosteroids ASAP; even before a TA biopsy can be arranged. As long as the biopsy is performed within 2 weeks of starting corticosteroids the results will not be affected. Treatment for AION There is no treatment for non-arteritic AION Arteritic GCA requires treatment with with high dose corticosteroids (preferably IV at the onset, followed by oral therapy) and this should be undertaken immediately. While the vision loss cannot be reversed, the goal is to address the vasculitis and restore perfusion before the fellow eye becomes involved. Topic 4 Papilledema is a term that should be reserved for optic nerve edema secondary to PROVEN increased intracranial pressure. Clinical Features Papilledema typically presents bilaterally. Optic nerve function is preserved early it its course. Vision can be compromised if there is macular edema from severe swelling and the visual fields will show enlargement of the blindspots. Optic nerve axonal compromise can occur if the papilledema is chronic resulting in optic atrophy and visual field loss. Absence of the spontaneous venous pulsation is typically seen at all stages due to venous engorgement. Related Anatomy and Physiology CSF is mainly produced by the choroid plexus of the lateral ventricles. It flows

9 9 through the interventricular foramina into the third ventricle, then through the cerebral aqueduct into the fourth ventricle. From there, it flows into the subarachnoid space. CSF is absorbed passively through the arachnoid granulations that protrude into the venous sinuses and diploic veins. These veins drain into the jugular veins. Increased CSF pressure is transmitted to the optic nerves along their meningeal sheaths. Perineural pressure interferes with the slow component of axoplasmic flow at the level of the lamina cribrosa with resulting disc edema. Types of Papilledema 1. Acute--Hemorrhages and exudates are apparent In addition to hyperemia and NFL edema 2. Chronic--Minimal or absent hemorrhage/edudate. Telangiectatic vessels on disc surface. Drusen-like bodies may be apparent. Optociliary shunt vessels may be present 3. Atrophic--Eventually occurs if papilledema remains chronic. Optic disc pallor with nerve fiber bundle visual field defects. Papilledema Symptoms Headache-nonspecific characteristics; often worsens with valsava maneuver. This is the most common symptom and is thought to occur from stretching of the meninges or cerebral veins Transient Visual Obscurations-mild blurring to complete blindness that lasts seconds. Precipitated by changes in posture and more commonly seen in chronic papilledema. It occurs from transient compression or ischemia to the optic nerve but has no bearing on visual outcome Tinnitus-Pulsatile quality reflecting flow disturbances in the cerebral venous system. Patients usually report a whooshing sound and it tends to be most prominent at night Diplopia-Typically due to abducens palsy. The abducens palsy is typically bilateral Visual Fields Enlarged blindspot due to the increased diameter of the nerve Arcuate loss with nasal involvement occurs as axons die off. Mechanisms of Increased ICP Increase in intracranial tissue by structural lesion Increase in intracranial tissue volume by cerebral edema Blockage of CSF flow within the ventricular system or arachnoid granulations Reduced absorption of CSF from obstruction or compromise of venous outflow (more on this later) Increased production of CSF

10 10 Diagnostic Approach Papilledema, particularly when acute, constitutes a medical emergency requiring immediate neuro-imaging to rule out an intracranial mass. If imaging is normal, lumbar puncture to measure CSF pressure and exclude meningitis or other disease processes is necessary. Evaluation of the intracranial veins is also undertaken. Pseudotumor Cerebri Increased intracranial pressure in the absence of clear intracranial disease Older term that used to imply idiopathic but additional causes have since been identified. Additional Causes of Increased ICP 1. Exogenous Agents-Tetracycline, Minocycline, corticosteroid use or withdrawal, hypervitaminosis A 2. Endocrine Abnormalities 3. Systemic Disorders-Lupus, iron deficiency, systemic hypertension with encephalopathy 4. Sleep apnea Diagnostic Work-Up for Papilledema Neuro-image-MRI to rule out structural lesion or any other intracranial disease process. Lumbar puncture to confirm increased ICP and analyze CSF constituents Magnetic Resonance Venogram to rule out venous sinus thrombosis which can impair CSF drainage Additional laboratory analysis to rule out systemic disease If a causative agent is identified, treatment of the disorder or removal of the offending exogenous agent will often result in resolution of the intracranial hypertension. If no causative agent is identified, the patient is considered to have idiopathic intracranial hypertension Idiopathic Intracranial Hypertension: Increased intracranial pressure in the absence of identifiable cause Typical patients are obese women of childbearing age Increased ICP likely due to diminished reabsorption of CSF PTC vs. IIH PTC, while not due causes that can be identified on an MRI or LP, can still occur from known medical conditions or medications. It is not necessarily idiopathic. IIH is reserved for truly idiopathic disease Proposed Mechanism for IIH Central obesity raises intra-abdominal pressure which increases pleural pressure and cardiac filling pressures

11 11 Venous return from brain is impeded Increased intracranial venous pressure results which increases intracranial pressure Management of Idiopathic Intracranial Hypertension (IIH) If the patient is asymptomatic and there is no optic nerve compromise, weight loss and careful monitoring of optic nerve function are all that are necessary visual fields are an important monitoring tool If the patient is symptomatic (headache or transient vision loss), acetazolamide (Diamox) 2-4g daily is used to lower CSF pressure along with monitoring of optic nerve function. Weight loss is the mainstay of management and studies have shown that a 6% reduction of weight may be adequate to bring about remission. However, this is often not maintained, resulting in the need for more aggressive approaches. In these instances, surgical remediation with gastric bypass or gastric banding procedures should be considered. The Idiopathic Intracranial Hypertension Treatment Trial is an ongoing study that is looking at optimum treatment regiments for this disorder. The results will be published in the near future. When optic nerve compromise occurs, surgical treatment with optic nerve sheath fenestration is considered. Lumboperitoneal shunting may be indicated in certain situations. Consider sleep studies if sleep apnea appears to be a factor. Sleep Apnea and Increased ICP Respiratory acidosis leads to accumulation of CO2, altering the CO2 tension ratio between CSF and arterial blood. Result is dilation of cerebral capillaries and increased intracranial pressure Given that obesity is a risk factor for both sleep apnea AND IIH, it is appropriate to consider sleep studies in patients with mild papilledema, especially if there is a history of snoring. Intracranial Venous Sinus Thrombosis Thrombosis within the venous sinuses of the brain can lead to poor absorption/drainage of CSF from the brain, leading to increased intracranial pressure. Risk factors include disorders that would cause a hypercoagulable state (see below), however, in many instances, it occurs without an identifiable hypercoagulopathy. In these latter situations, it has been proposed that venous hypertension without thrombosis is responsible and it is possible that there is a spectrum of severity with obesity being a contributing factor. The clinical presentation is indistinguishable from IIH. Radiographic investigation of the cerebral venous system is needed to identify evidence of thrombosis and this is accomplished with Magnetic Resonance Venography. Morbidity and mortality with venous thrombosis can be as high as 30% due to risk of CVA, pulmonary embolism, seizures or the underlying disease that s causing the thrombosis (eg neoplasm or infection)

12 12 When is papilledema an emergency? Papilledema, particularly when acute, constitutes a medical emergency requiring immediate neuro-imaging to rule out an intracranial mass. If imaging is normal, lumbar puncture to measure CSF pressure and exclude meningitis or other disease processes is necessary. If the papilledema is atrophic and there is substantial vision/field loss, urgent measures must be undertaken to prevent blindness, even if the underlying cause is idiopathic or benign. If the papilledema is accompanied by any neurologic abnormalities, fever or stiff neck, this might be indicative of a serious underlying neurologic abnormality, intracranial infection or bleed that requires immediate medical attention. Topic 5 Horner s syndrome An interruption of the oculosympathetic nerve supply somewhere between its origin in the hypothalamus and its termination in the eye. The classic findings associated with Horner s syndrome are ptosis, pupillary miosis, and facial anhydrosis. Sympathetic innervation to the eye involves a continuous pathway involving three neurons. The first neuron (considered a central neuron) originates in the dorsolateral hypothalamus, descending through the brain stem and traveling to the ciliospinal center of Budge, between the levels of the eighth cervical and fourth thoracic vertebrae (C8-T4) of the spinal cord. It then synapses with the second neuron (which is considered preganglionic) whose cell bodies give rise to axons, which exit the white rami communicates of the spinal cord via the anterior horn. These axons pass over the apex of the lung and enter the sympathetic chain in the neck, synapsing in the superior cervical ganglion. At this point the third neuron gives rise to post-ganglionic axons that course to the eye to form the long and short posterior ciliary nerves. These sympathetic nerve fibers course anteriorly through the uveal tract and join the fibers of long posterior ciliary nerves to innervate the dilator of the iris. Sympathetic fibers also innervate the muscle of Müller, responsible for initiating eyelid retraction during eyelid opening. Damage at any location along this pathway (central, pre-ganglionic or post-ganglionic) will induce an ipsilateral Horner s syndrome. The diagnosis and localization of Horner s syndrome can be accomplished with pharmacological testing. o In this dysfunction, there is a lack of the sympathetic neurotransmitter norepinephrine. The iris dilator does not receive sympathetic stimulation in Horner s syndrome, thus accounting for the miosis which increases in dim light conditions and the dilation lag (relative to the normal contralateral pupil) when the lights go down. o Previously, topical cocaine was used to identify if Horner s syndrome was present and hydroxyamphetamine was used to differentiate a third order from a first/ second order lesion. However, these drugs are not readily available for clinical practice.

13 13 o Apraclonidine is a viable replacement. Apraclonidine (0.5% and 1%) is an alpha- 2 adrenergic agonist which seems to also stimulate alpha-1 receptors to a negligible degree. Pupil dilation in suspected Horner s syndrome is considered diagnostic. The theory is that the Horner s syndrome pupil undergoes denervation hypersensitivity. When a very weak alpha-1 adrenergic agonist is applied, the hypersensitive pupil dilates while the normal pupil has no effect. In most cases, there will actually be a reversal of the anisocoria, which is easier to appreciate than the asymmetric dilation induced by cocaine. It appears that the most readily available agent, apraclonidine 0.5% (Iopidine) is at least as sensitive and specific in the diagnosis of Horner s syndrome as is cocaine Localizable- targeted workup Neck and facial pain- carotid dissection Facial paraesthesia- middle cranial fossa disease Necessary Work Up (non-localizable): MRI of brain, orbits and chiasm with and without contrast, attention to middle cranial fossa. MRA of head and neck-rule out carotid dissection MRI of neck and cervical spine, include lung apex and brachial plexus Horner s syndrome patient needs to be imaged from chest to head- 3 scans Horner s protocol When is it an emergency? A 3rd-order Horner s and ipsilateral head, eye, or neck pain of acute onset should be considered diagnostic of internal carotid dissection unless proven otherwise. Carotid artery dissection presents with the sudden or gradual onset of ipsilateral neck or hemicranial pain, including eye or face pain Often associated with other neurologic findings including an ipsilateral Horner s syndrome, TIA, stroke, anterior ischemic optic neuropathy, subarachnoid hemorrhage, or lower cranial nerve palsies Horner s from suspected carotid dissection should immediately go to hospital emergency room/ emergency department Orbital Disease Topic 6 Clinical Presentation of Orbital Disease Proptosis Diplopia with EOM restrictions and positive forced ductions Optic nerve edema or atrophy Gaze-evoked amaurosis Orbital congestion Pain

14 14 Differential Diagnosis 1. Inflammatory Orbital Pseudotumor This is a type of idiopathic orbital inflammatory disease that involves extraocular muscles. It is accompanied by severe pain with the whole muscle (including the insertions) involved as evidenced on CT. It is typically unilateral and can be accompanied by proptosis. Compressive optic neuropathy can result if the inflammation is severe. While forced ductions would be positive, this test is rarely needed for diagnosis. Treatment is with high-dose corticosteroids and response is typically quite rapid. 2. Orbital Tumors Usually painless and unilateral. Proptosis is often apparent and can displace the eye if the tumor lies outside the muscle cone. Tumors can also infiltrate muscles and appear very similar to Graves orbitopathy on imaging studies, but you would not expect to see lid retraction and/or a bilateral presentation like you would in Graves. 3. Orbital Trauma Orbital trauma can result in fractures that entrap EOMs to result in diplopia with positive forced ductions. Inferior rectus and medial rectus are most likely to be affected by inferior or medial wall fractures, resulting in loss of ugaze or abduction respectively. The case history is an important tool in differential diagnosis. In addition, orbital fractures are more likely to result in enophthalmos although exopthalmos can occur when there is orbital hemorrhage or severe edema. 4. Orbital Infections Infectious diseases of the orbit will typically cause proptosis with limited eye movements. Presentation is usually unilateral and the patient may be febrile. Pain is typical, especially in orbital cellulitis and aggressive intravenous antibiotic treatment is generally undertaken. In uncontrolled diabetics or immunocompromised individuals, mycotic infections should always be considered and these typically have a rapid onset and are a serious threat to life. 5. Graves Disease-autoimmune disorder in which antibodies are directed against the thyroid gland, orbital fat and extraocular muscles. Its ocular presentation includes ocular, orbital and periorbital congestion, eyelid retraction, EOM restrictions with diplopia, and proptosis. Severe cases can cause blindness due to compression of the optic nerves by enlarged EOMs or severe desiccation of the cornea with bullous keratopathy due to severe lid retraction. When is orbital disease an emergency? In any orbital process that is causing compromise to the optic nerve, urgent measures should be taken to prevent permanent visual deficits. In Graves orbitopathy patients that have visual decrease due to compressive optic neuropathy from enlarged EOMs. This can evolve rapidly, therefore,

15 15 immediate attention is needed so that treatment with immunosuppressive agents, radiation or decompressive surgery can be instituted. In addition, any Graves patient who has a rapidly evolving onset of orbital signs requires rapid treatment with immunosuppressive agents because visual compromise can rapidly ensue. Finally, any Graves patient with severe corneal compromise from exposure requires immediate intervention to prevent permanent blindness. When orbital infection is suspected as indicated by fever and periorbital redness. The orbital apex provides a direct entry into the cranial cavity and extension of an orbital infection into the brain has serious consequences. This is particularly true in a diabetic or immunocompromised individual because mycotic infections are a serious threat to life. Orbital trauma that compromises optic nerve function may require urgent surgical decompression of the optic nerve in order to prevent permanent vision loss. In addition, when an orbital fracture creates an opening into the sinuses, infection is a risk and this should be addressed urgently.