[06.19] CMD - Orbit and Proptosis V2.pdf

Proptosis

What is the medical term for the abnormal protrusion of the eyeball beyond the boundaries of the bony orbit?

Skull cavity

In what anatomical cavity of the skeleton is the eye and its appendages situated?

Anteriorly

In which direction is the bony orbit open or unenclosed?

Five

How many sides of the bony orbit are enclosed by bone?

Pear-shaped

What is the overall geometric shape of the orbital cavity?

Apex

To what anatomical region does the pear-shaped orbit taper posteriorly?

30 cc

What is the total volume of each individual bony orbit?

One-fifth (1/5)

What proportion of the total orbital volume is occupied by the eyeball itself?

6 cc

What is the approximate numerical volume occupied by the eyeball within the 30 cc orbital cavity?

18 mm

What is the distance between the back of the globe and the optic foramen?

25 to 30 mm

What is the total length of the optic nerve from the back of the globe to its intracranial exit?

S-shaped configuration

What geometric configuration does the intraorbital optic nerve display?

Extra length and S-shaped curve

What structural features of the optic nerve allow the globe to protrude forward without immediate loss of optic nerve function?

Protrusion of the eyeball

What occurs when an expanding lesion develops within the confined space of the orbit?

Location of the lesion

What determines the direction in which the eyeball is displaced during proptosis?

VITAMIN CE

What is the primary mnemonic representing all major categories of etiologies for proptosis?

Vascular

In the VITAMIN CE mnemonic, what category does the letter 'V' represent?

Infection

In the VITAMIN CE mnemonic, what category does the letter 'I' represent?

Traumatic

In the VITAMIN CE mnemonic, what category does the letter 'T' represent?

Autoimmune

In the VITAMIN CE mnemonic, what category does the letter 'A' represent?

Metabolic

In the VITAMIN CE mnemonic, what category does the letter 'M' represent?

Iatrogenic

In the VITAMIN CE mnemonic, what category does the second 'I' represent?

Neoplastic

In the VITAMIN CE mnemonic, what category does the letter 'N' represent?

Congenital

In the VITAMIN CE mnemonic, what category does the letter 'C' represent?

Endocrine

In the VITAMIN CE mnemonic, what category does the letter 'E' represent?

Infantile hemangiomas, cavernous vascular malformations, and carotid-cavernous fistulas

What are three vascular causes of proptosis?

Direct and indirect

What are the two anatomical types of carotid-cavernous fistulas that cause proptosis?

Carotid artery and cavernous sinus

Between which two vascular structures does an abnormal communication form in a carotid-cavernous fistula?

OCP

What mnemonic summarizes the major infectious causes of proptosis?

Orbital cellulitis

In the OCP infectious mnemonic, what condition does 'O' stand for?

Cavernous sinus thrombosis

In the OCP infectious mnemonic, what condition does 'C' stand for?

Panophthalmitis

In the OCP infectious mnemonic, what condition does 'P' stand for?

Multiple orbital fractures

What traumatic injury causes overlapping of orbital bones and alters orbital volume?

Retrobulbar hemorrhage

What traumatic condition involves blood accumulation behind the globe, displacing the eyeball forward?

Orbital inflammatory disease

What autoimmune condition is characterized by non-infectious, non-neoplastic orbital inflammation?

Aggressive rehydration therapy

What documented metabolic intervention can rarely precipitate proptosis?

Rare

How is the clinical incidence of metabolic causes of proptosis categorized?

Thyroid Related Eye Disease (TRED)

What is the most common cause of both unilateral and bilateral proptosis in adults?

Thyroid Related Eye Disease, inflammatory orbital disease, and Wegener's granulomatosis

What are three inflammatory causes of proptosis?

Granulomatosis with Polyangiitis

What is the alternative clinical name for Wegener's granulomatosis?

Benign, malignant, and metastatic tumors

What are the three pathological types of neoplastic lesions that cause proptosis?

Squamous cell carcinoma

What epithelial malignancy is documented as a neoplastic cause of proptosis?

Dermoid cysts and encephalocoele

What are two congenital lesions that can cause proptosis?

Anteriorly

Where are dermoid cysts typically located when they present near the eye?

Within the orbit

In what specific location must a dermoid cyst be situated to cause proptosis?

Encephalocoele

What congenital defect involving herniation of brain tissue or meninges into the orbit causes proptosis?

Endocrine cause

To what etiology category does Thyroid Related Eye Disease (TRED) belong?

Thyroid Related Eye Disease (TRED)

What is the single overall most common etiology of proptosis?

Onset and direction

What are the two major systems used to classify proptosis?

Minutes to hours

What is the timeframe for the development of acute proptosis?

Trauma

What is the primary etiology responsible for acute proptosis?

Retrobulbar trauma and retrobulbar hemorrhage

What are two specific traumatic events that present as acute proptosis?

Days to weeks

What is the timeframe for the development of subacute proptosis?

Infection

What is the primary etiology responsible for subacute proptosis?

Orbital cellulitis

What specific infectious condition characteristically presents as subacute proptosis?

Months

What is the timeframe for the development of chronic proptosis?

Neoplastic causes (tumors)

What is the primary etiology responsible for chronic proptosis?

Opposite

In what direction relative to the causative lesion does the eyeball protrude during proptosis?

Opposite to the location of the mass

If a lesion is located in the inferior orbit, in which direction is the globe displaced?

Corneal light reflexes

What physical examination finding is evaluated to detect ocular symmetry or subtle globe displacement?

Axial proptosis (anterior displacement)

What direction of globe displacement is caused by retrobulbar masses or muscle cone lesions?

Retrobulbar mass

What location of orbital lesion causes direct anterior (axial) proptosis?

Inferior orbital mass

What location of orbital lesion causes superior displacement of the globe?

Superior displacement

In what direction is the globe pushed when a tumor grows in the floor of the orbit?

Upper and inner orbit

Where are dermoid cysts, ethmoid lesions, or frontal sinus lesions located when they displace the eye down and forward?

Down and forward

In what direction is the eyeball displaced by lesions in the upper and inner orbit?

Nasopharyngeal carcinoma

What specific malignancy causes outward displacement of the globe?

Outward

In what direction is the globe displaced by nasopharyngeal carcinoma?

Maxillary sinus carcinoma

What specific malignancy causes upward displacement of the globe?

Upward

In what direction is the globe displaced by maxillary sinus carcinoma?

Medial orbital mass or lacrimal sac mass

What location of lesion causes lateral displacement of the eyeball?

Lateral displacement

In what direction is the globe displaced by a mass arising from the lacrimal sac?

Exposure keratopathy, diplopia, and optic nerve compression

What are the three major clinical problems or complications associated with proptosis?

Inability to close the eye completely and poor blinking

What causes exposure keratopathy in a patient with proptosis?

Lagophthalmos

What medical term describes the inability to close the eyelids completely over the globe?

Corneal drying, corneal abrasions, and corneal ulcers

What sequence of corneal damage results from exposure keratopathy in severe proptosis?

Eyeball displacement and extraocular muscle enlargement

What causes restriction of ocular movements and diplopia in proptosis?

Diplopia

What symptom results when ocular misalignment and extraocular muscle restriction prevent binocular single vision?

Enlargement of extraocular muscles

What mechanism compresses the optic nerve at the orbital apex in severe proptosis or TRED?

Orbital apex

At what anatomical location does extraocular muscle enlargement cause optic nerve compression?

Immediate emergency management

What level of clinical urgency is required when optic nerve compression occurs in proptosis?

Blindness

What irreversible complication can result from unmanaged optic nerve compression?

Onset and clinical course

What two key historical elements must be elicited during patient interview to narrow the differential diagnosis of proptosis?

Visual acuity, gross examination, extraocular muscle movements, intraocular pressure, and fundus exam

What five components comprise the mandatory 5-point eye examination for all ophthalmology patients?

Visual acuity

What is the first parameter assessed in the standard 5-point eye examination?

Gross examination

Which step of the 5-point eye exam involves inspecting the eyelids, conjunctiva, cornea, and globe symmetry?

Extraocular muscle movements

Which step of the 5-point eye exam assesses ocular motility and identifies muscle entrapment or restriction?

Intraocular pressure

Which step of the 5-point eye exam measures the pressure inside the eye, which may be elevated in orbital mass lesions?

Fundus exam

Which step of the 5-point eye exam inspects the optic disc, macula, and retinal vasculature for optic disc swelling or choroidal folds?

Hertel's examination

What specialized clinical examination is performed specifically to quantify the severity of proptosis?

Exophthalmometer (Hertel exophthalmometer)

What instrument is used during a Hertel's examination to measure globe protrusion?

Corneal tip

What anterior anatomical landmark's position is measured during Hertel's exophthalmometry?

Lateral orbital rim

What bony anatomical reference point is used during Hertel's exophthalmometry to measure corneal protrusion?

CT scan and MRI

What two neuroimaging modalities are very important for evaluating the location, extent, and nature of orbital lesions?

CT scan

Which imaging modality is particularly useful for evaluating bony orbital structures and calcified orbital masses?

MRI

Which imaging modality provides superior soft-tissue resolution for orbital tumors, extraocular muscles, and the optic nerve?

Biopsy and histopathology

What diagnostic procedure provides definitive identification of the specific tumor type in an orbital mass?

Treating the underlying cause

What is the primary definitive goal in the management of proptosis?

Multidisciplinary team approach

What collaborative care approach is required to manage proptosis given its diverse vascular, endocrine, infectious, and neoplastic etiologies?

1/5 (one-fifth)

What fraction of the orbital volume is taken up by the eyeball?