Eye: Orbit

DIFFERENTIAL DIAGNOSIS OF ORBITAL AND OCULAR DISORDERS

OPHTHALMOPLEGIA

Lesions of

Oculomotor nerve (CN III) innervates medial rectus, superior rectus, inferior rectus, inferior oblique muscle, pupilloconstrictor, levator palpebrae
Trochlear nerve (CN IV) innervates superior oblique muscle
Abducens nerve (CN VI) innervates lateral rectus muscle

ANOPIA

[numbers refer to drawing]

MONOCULAR DEFECTS

1 = monocular blindness (optic nerve lesion in fracture of optic canal, amaurosis fugax)
BILATERAL heteronymous DEFECTS

2 = bitemporal hemianopia (chiasmatic lesion)
BILATERAL HOMONYMOUS DEFECTS

3 = homonymous hemianopia

4 = upper right-sided quadrantanopia

5 = central hemianoptic scotoma

3,4,5 = most common type of hemianopia (CVA, brain tumor)

Monocular Blindness In Adulthood

Optic neuritis
Vascular ischemia
- Amaurosis fugax = cholesterol emboli from internal carotid artery occluding central retinal artery and its branches
- Occult cerebrovascular malformation affecting the optic nerve
Temporal arteritis
Malignant optic glioma of adulthood

Types of Anopia

ORBIT

Spectrum of Orbital Disorders

INFLAMMATORY DISEASE
- Tissue-specific inflammation: orbital cellulitis, optic neuritis, scleritis, myositis, Graves disease
- Panophthalmitis
- Pseudotumor of orbit
CYSTIC DISEASE
- Dermoid cyst
- Mucocele
- Retroocular cyst (developmental)
VASCULAR LESIONS
- arterial and arteriovenous lesion
  
  1. Ophthalmic artery aneurysm
  
  2. Arteriovenous fistula (rare) eg, Wyburn-Mason syndrome
  
  3. Carotid-cavernous fistula
- capillary lesion
  
  4. Capillary hemangioma/benign hemangioendotheliloma
- venous vascular malformation
  
  5. Cavernous hemangioma
  
  6. Orbital varix
- venous lymphatic malformation
  
  7. Capillary lymphangioma
  
  8. Cavernous lymphangioma
  
  9. Cystic lymphangioma
TUMORS
- Rhabdomyosarcoma
- Optic nerve glioma
- Meningioma
- Lymphoma
- Metastasis
- Hemangiopericytoma

Intraconal Lesion

mnemonic: Mel Met Rita Mending Hems On Poor Charlie’s Grave

Melanoma

Metastasis

Retinoblastoma

Meningioma

Hemangioma

Optic glioma

Pseudotumor

Cellulitis

Grave disease

Intraconal Lesion with Optic Nerve Involvement

Optic nerve glioma
Optic nerve sheath meningioma (10% of orbital neoplasm)
Optic neuritis
Inflammatory pseudotumor (may surround optic nerve)
Sarcoidosis
Intraorbital lymphoma (may surround optic nerve, older patient)
Elevated intracranial pressure

= distension of optic sheath

[check mark] bilateral tortuous enlarged optic nerve-sheath complex

OPTIC NERVE TRAM-TRACK SIGN

Optic nerve sheath meningioma
Orbital pseudotumor
Perioptic neuritis
Perioptic hemorrhage
Sarcoidosis
Lymphoma/leukemia
Metastasis
Erdheim-Chester disease = systemic xanthogranulomatosis

Intraconal Lesion without Optic Nerve Involvement

Cavernous hemangioma
Orbital varix
Carotid-cavernous fistula
Arteriovenous malformation

least common of orbital vascular malformations (congenital, idiopathic, traumatic)

[check mark] irregularly shaped intensely enhancing mass of enlarged vessels

[check mark] associated with dilated superior/inferior ophthalmic vein
Hematoma
Lymphangioma
Neurilemmoma

[check mark] commonly adjacent to superior orbital fissure, inferior to optic nerve

[check mark] local bone erosion

Extraconal Lesion

Extraconal-intraorbital Lesion

BENIGN TUMOR
- Dermoid cyst
- Teratoma
  
  <1% of all pediatric orbital tumors
  
  [check mark] ± areas of fat, cartilage, bone
  
  [check mark] expansion of bony orbit ± bone defect
- Capillary hemangioma
- Lymphangioma
- Plexiform neurofibroma
- Inflammatory orbital pseudotumor
- Histiocytosis X lesion usually arises from bone
MALIGNANT TUMOR
- Lymphoma/leukemia
- Metastasis
- Rhabdomyosarcoma

mnemonic: MOLD

Metastasis

Others (rhabdomyosarcoma, lymphangioma, sinus lesion)

Lymphoma, Lacrimal gland tumor

Dermoid

Extraconal-extraorbital Lesion

FROM SINUS

maxillary/sphenoid sinuses are rare locations of origin
- Tumor:
  
  squamous cell carcinoma (80%), lymphoma, adenocarcinoma, adenoid cystic carcinoma
- Mucocele
- Paranasal sinusitis:
  
  ♦ Most common cause of orbital infection!
  
  Origin: from ethmoid sinuses (in children), from frontal sinus (in adolescence)
  
  Organism: Staphylococcus, Streptococcus, Pneumococcus
  
  [check mark] preseptal/orbital edema/cellulitis
  
  [check mark] subperiosteal/orbital abscess
  
  [check mark] mucormycosis (in diabetics) destroys bone + extends into cavernous sinus
  
  Cx:
  - epidural abscess
  - subdural empyema
  - cavernous sinus thrombosis
  - meningitis
  - cerebritis
  - brain abscess
FROM SKIN
- Orbital cellulitis
FROM LACRIMAL GLAND

[check mark] mass arising from superolateral aspect of orbit

Dilatation of Superior Ophthalmic Vein

Carotid-cavernous sinus fistula
Cavernous sinus thrombosis
Venous varix
Graves disease
Normal variant

ORBITAL MASS

Orbital Mass in Childhood

1.	Dermoid cyst	46%
2.	Inflammatory lesion	16%
3.	Dermolipoma	7%
4.	Capillary hemangioma	4%
5.	Rhabdomyosarcoma	4%
6.	Leukemia/lymphoma	2%
7.	Optic nerve glioma	2%
8.	Lymphangioma	2%
9.	Cavernous hemangioma	1%
mnemonic: LO VISHON
	Leukemia, Lymphoma
	Optic nerve glioma
	Vascular malformation: hemangioma, lymphangioma
	Inflammation
	Sarcoma: ie, rhabdomyosarcoma
	Histiocytosis
	Orbital pseudotumor, Osteoma
	Neuroblastoma

Primary Malignant Orbital Tumors

1.	Retinoblastoma	86.0%
2.	Rhabdomyosarcoma	8.1%
3.	Uveal melanoma	2.3%
4.	Sarcoma	1.7%

Secondary Malignant Orbital Tumors

1.	Leukemia	36.7%
2.	Sarcoma	14.3%
3.	Hodgkin lymphoma	11.0%
4.	Neuroblastoma	9.2%
5.	Wilms tumor	6.7%
6.	Non-Hodgkin lymphoma	5.6%
7.	Histiocytosis	3.9%
8.	Medulloblastoma	3.5%

Orbital Cystic Lesion

Abscess
Intraorbital hematoma
Dermoid cyst
Lacrimal cyst
Lymphangioma
Hydatid cyst

Orbital Vascular Tumors

Orbital varix
Arteriovenous malformation
Carotid-cavernous fistula
Hemangioma: capillary/cavernous
Blood cyst
Arterial malformation
Glomus tumor
Hemangiopericytoma

Mass in Superolateral Quadrant of Orbit

Lacrimal gland tumor
Dermoid cyst
Metastasis (breast, prostate, lung)
Lymphoma
Leukemic infiltration of lacrimal gland
Sarcoidosis
Wegener granulomatosis
Pseudotumor
Frontal sinus mucocele

Extraocular Muscle Enlargement

ENDOCRINE
- Graves disease (50%)
- Acromegaly
INFLAMMATION
- Myositis
  
  • rapid onset of proptosis, erythema of lids, conjunctival injection
  
  Location: single muscle (in adults); multiple muscles (in children)
  
  [check mark] enlarged extraocular muscle
  
  [check mark] positive response to steroids
- Orbital cellulitis
- Sjögren disease, Wegener granulomatosis, lethal midline granuloma, SLE
- Sarcoidosis
- Foreign-body reaction
TUMOR
- Pseudotumor
- Rhabdomyosarcoma
- Metastasis, lymphoma, leukemia
VASCULAR
- Spontaneous/traumatic hematoma
- Arteriovenous malformation
- Carotid-cavernous sinus fistula

GLOBE

Spectrum of Ocular Disorders

CONGENITAL
- Persistent hyperplastic primary vitreous
- Coats disease
- Coloboma
- Congenital cataract
vitreoretinal
- Vitreous hemorrhage
- Retinal detachment
- Choroidal detachment
- Endophthalmitis
- Retinoschisis
- Retrolental fibroplasia
TUMOR
- Retinoblastoma
- Choroidal hemangioma
- Retinal angiomatosis
- Melanocytoma
- Choroidal osteoma
TRAUMA

Microphthalmia

= congenital underdevelopment/acquired diminution of globe

BILATERAL with cataract
- Congenital rubella
- Persistent hyperplastic vitreous
- Retinopathy of prematurity
- Retinal folds
- Lowe syndrome
  
  [check mark] small globe + small orbit
UNILATERAL
- Trauma/surgery/radiation therapy
- Inflammation with disorganization of eye (phthisis bulbi)
  
  [check mark] shrunken calcified globe + normal orbit

Macrophthalmia

= enlargement of globe

WITHOUT INTRAOCULAR MASS
- generalized enlargement
  - Axial myopia (most common cause)
    
    [check mark] enlargement of globe in AP direction
    
    [check mark] ± thinning of sclera
  - Buphthalmos
  - Juvenile glaucoma
  - Connective tissue disorder:
    
    Marfan syndrome, Ehlers-Danlos syndrome,
    
    Weill-Marchesani syndrome (congenital
    
    mesodermal dysmorphodystrophy),
    
    homocystinuria
    
    [check mark] “wavy” contour of sclera
- focal enlargement
  - Staphyloma
  - Apparent enlargement due to contralateral microphthalmia
WITH INTRAOCULAR MASS (rare cause for enlargement)
- with calcifications:
  - Retinoblastoma
- without calcifications:
  - Melanoma
  - Metastasis

Deformity of Globe Contour

Open-globe injury
Posttraumatic orbital hematoma
Coloboma
Staphyloma

Orbital Calcifications

Extraocular Calcifications

Trochlear calcifications

= aging-related normal variant/young diabetic patient Location: superomedial orbit

Intraocular Calcifications

Retinoblastoma (>50% of all cases)
Astrocytic hamartoma
Choroidal osteoma
Optic drusen

[check mark] punctate calcifications near optic disc
Scleral calcifications
- in systemic hypercalcemic states (HPT, hypervitaminosis D, sarcoidosis, secondary to chronic renal disease)
- in elderly: at insertion of extraocular muscles, esp. medial + lateral rectus mm.
Retrolental fibroplasia
Phthisis bulbi

Cause: trauma or infection/inflammation

[check mark] small contracted/shrunken calcified/ossified disorganized nonfunctioning globe

mnemonic: NMR CT

Neurofibromatosis

Melanoma (hyperdense melanin)

Retinoblastoma

Choroidal osteoma

Tuberous sclerosis

Posttherapeutic Orbital Changes

Lens implant
Scleral buckle

[check mark] radiopaque/radiolucent device at midglobe level
Intraocular silicone oil injection

[check mark] silicone >100 HU (DDx: blood <90 HU)

[check mark] silicone-related chemical shift artifact
Pneumatic retinopexy

[check mark] gas within globe
Globe prosthesis

Noncalcified Ocular Lesion

Uveal melanoma
Metastasis

86% of ocular lesions within globe; usually in vascular choroid

Origin: breast, lung, GI tract, GU tract, cutaneous melanoma, neuroblastoma

[check mark] bilateral in 30%
Choroidal hemangioma
Vitreous lymphoma

[check mark] diffuse ill-defined soft-tissue density
Developmental anomalies
- Primary glaucoma = enlargement of eye secondary to narrowing of Schlemm canal
- Coloboma
- Staphyloma

Vitreous Hemorrhage

Cause: trauma, surgical intervention, arterial hypertension, retinal detachment, ocular tumor, Coats disease

• visual loss frequent

US:

numerous irregular, poorly defined low-intensity echoes:
echogenic material moving freely within vitreous chamber during eye movement
voluminous hyperechoic fibrin clots not fixed to optic nerve (DDx to retinal detachment)

Prognosis: complete absorption/development of vitreous membranes (repetitive episodes)

Cx: retinal detachment (vitreous traction secondary to fibrovascular ingrowth following hemorrhage)

Dense Vitreous in Pediatric Age Group

Retinoblastoma
Persistent hyperplastic primary vitreous
Coats disease
Norrie disease
Retrolental fibroplasia
Sclerosing endophthalmitis

Leukokoria

= abnormal white/pinkish/yellowish pupillary light reflex [leuko, Greek = white and koria, Greek = pupil]

TUMOR
- Retinoblastoma (most common cause — 58%)
- Retinal astrocytic hamartoma (3%):
  
  associated with tuberous sclerosis + von Recklinghausen disease
- Medulloepithelioma (rare)
DEVELOPMENTAL
- Persistent hyperplastic primary vitreous (2nd most common cause in 19-28%)
- Coats disease (4-16%)
- Retrolental fibroplasia (3-5%)
- Coloboma of choroid/optic disc (11%)
INFECTION
- Uveitis
- Larval endophthalmitis/granulomatosis (7-16%)
DEGENERATIVE
- Posterior cataract (13%)
TRAUMA
- Retinopathy of prematurity (5-13%)
- Organized vitreous hemorrhage
- Long-standing retinal detachment

Leukokoria in Normal-sized Eye

CALCIFIED MASS
- Retinoblastoma
- Retinal astrocytoma
NONCALCIFIED MASS
- Toxocara endophthalmitis
- Coats disease

Leukokoria with Microphthalmia

UNILATERAL
- Persistent hyperplastic primary vitreous (PHPV)
BILATERAL
- Retinopathy of prematurity
- Bilateral PHPV

OPTIC NERVE

Optic Nerve Enlargement

TUMOR:
- Optic nerve glioma
- Optic nerve sheath meningioma
- Infiltration by leukemia/lymphoma
FLUID:
- Perineural hematoma
- Papilledema of intracranial hypertension
- Patulous subarachnoid space
INFLAMMATION:
- Optic neuritis
- Sarcoidosis

fusiform thickening

= lens-shaped thickening of nerve-sheath complex
- with central lucency: meningioma
- without central lucency: optic nerve glioma
excrescentic thickening

= single/multiple nodules along nerve-sheath complex usually due to tumor
tubular enlargement

= uniform enlargement of nerve-sheath complex
- with central lucency: subarachnoid process (metastases, perineuritis, meningioma, perineural hemorrhage)
- without central lucency: papilledema, leukemia, lymphoma, sarcoid, optic nerve glioma

LACRIMAL GLAND

Lacrimal Gland Lesion

INFLAMMATION
- Dacryoadenitis
- Mikulicz syndrome
  
  = nonspecific enlargement of lacrimal + salivary glands
  
  Associated with: sarcoidosis, lymphoma, leukemia
- Sjögren syndrome
  
  = lymphocytic infiltration of lacrimal + salivary glands
  
  • decreased lacrimation, xerostomia
  
  Often associated with: rheumatoid arthritis, systemic lupus erythematosus, scleroderma, polymyositis
- Sarcoidosis
TUMOR
- benign: granuloma, cyst, benign mixed tumor (= pleomorphic adenoma)
- malignant: malignant mixed tumor (= pleomorphic adenocarcinoma), adenoid cystic carcinoma, lymphoma, metastasis (rare)

Lacrimal Gland Enlargement

mnemonic: MELD

Metastasis

Epithelial tumor

Lymphoid tumor

Dermoid

Bilateral Lacrimal Gland Masses

mnemonic: LACS

Lymphoma

And

Collagen-vascular disease

Sarcoidosis

ANATOMY OF ORBIT

ORBIT

[orbita, Latin = wheel track, course, path]; [oculus, Latin = eye]

= four-sided pyramidal space formed by 7 bones

Floor: maxilla, zygoma, palatine

Roof: orbital plate of the frontal bone, lesser wing of the sphenoid

Medial wall: ethmoid, lacrimal bone

Normal orbit measurements

6 extraocular muscles
	medial rectus muscle	4.1 ± 0.5 mm
	inferior rectus muscle	4.9 ± 0.8 mm
	superior rectus muscle	3.8 ± 0.7 mm
	lateral rectus muscle	2.9 ± 0.6 mm
	superior oblique muscle	2.4 ± 0.4 mm
		inferior oblique muscle
Superior ophthalmic vein
	axial CT	1.8 ± 0.5 mm
	coronal CT	2.7 ± 1.0 mm
Optic nerve sheath
	retrobulbar	5.5 ± 0.8 mm
	waist	4.2 ± 0.6 mm
Globe position
	behind interzygomatic line	9.9 ± 1.7 mm

Orbital compartments

the orbital septum + globe divide orbit into

ANTERIOR COMPARTMENT

lids, lacrimal apparatus, anterior soft tissues
POSTERIOR COMPARTMENT

= RETROBULBAR SPACE = the cone consisting of extraorbital muscles + envelope of fascia divides retrobulbar space into
- intraconal space
- extraconal space

ORBITAL CONNECTIONS

Superior Orbital Fissure

Boundaries (Gray’s Anatomy):

medial: sphenoid body
above: lesser wing of sphenoid = optic strut
below: greater wing of sphenoid
lateral: small segment of frontal bone

Coronal Orbital Tomogram through Midorbit

Contents:

nerves: III oculomotor n.

IV trochlear n.

V₁ ophthalmic branch of trigeminal n.:
- lacrimal nerve
- frontal nerve
VI abducens n.

sympathetic filaments of internal carotid plexus
veins: superior + inferior ophthalmic vein
arteries: 1. meningeal branch of lacrimal artery

2. orbital branch of middle meningeal artery

Inferior Orbital Fissure

Location: between floor + lateral wall of orbit; connects with pterygopalatine + infratemporal fossa

Contents:

nerves: infraorbital + zygomatic nn. branches from pterygopalatine ganglion
veins: connection between inferior orbital v. + pterygoid plexus

Optic Canal

completely formed by lesser wing of sphenoid

Sagittal Orbital Tomogram through Midorbit Orbital Spaces

globe: subdivided into anterior + posterior segments by lens

optic nerve

-sheath complex: optic nerve surrounded by meningeal sheath as extension from cerebral meninges

intraconal space: orbital fat, ophthalmic a., superior ophthalmic v., nerves I, III, IV, V₁, VI

conus: incomplete fenestrated musculofascial system extending from bony orbit to anterior third of globe, consists of extraocular muscles + interconnecting fascia

extraconal space: between muscle cone + bony orbit containing fat, lacrimal gland, lacrimal sac, portion of superior ophthalmic v

Contents:

nerve: optic nerve (I)
vessel: ophthalmic a.

GLOBE

Wall: composed of 3 layers:

fibrous outermost layer

1. Sclera

2. Cornea
pigmented vascular middle layer = uvea (Lat., grape)

3. Ciliary body (anteriorly)

4. Choroid (posteriorly)

Attachment: tethered to sclera by arteries + veins
innermost sensory layer

5. Retina

Attachment: firm at anterior margin (= ora serrata) and posteriorly at optic disk

Contents:

anterior segment containing

1. Aqueous humor subdivided by iris into:
- anterior chamber
- posterior chamber
posterior segment containing

2. Vitreous humor

LENS

connected to sclera by radially oriented zonular fibers

OPTIC NERVE SHEATH

= extension of dura mater

Content:

Optic nerve
Ophthalmic artery
Small veins

Orbital spaces

globe:

subdivided into anterior + posterior segments by lens

optic nerve-sheath complex:

optic nerve surrounded by meningeal sheath as

extension from cerebral meninges

intraconal space:

orbital fat, ophthalmic a., superior ophthalmic v., nerves I, III, IV, V₁, VI

conus:

incomplete fenestrated musculofascial system extending from bony orbit to anterior third of globe, consists of extraocular muscles + interconnecting fascia

extraconal space:

between muscle cone + bony orbit containing fat, lacrimal gland, lacrimal sac, portion of superior ophthalmic v.

ORBITAL AND OCULAR DISORDERS

BUPHTHALMOS

= HYDROPHTHALMOS = MEGOPHTHALMOS

= diffuse enlargement of eye in children secondary to increased intraocular pressure

Cause:

Congenital/infantile glaucoma
Neurofibromatosis type 1: obstruction of canal of Schlemm by membranes/masses composed of aberrant mesodermal tissue
Sturge-Weber-Dimitri syndrome
Lowe (cerebrohepatorenal) syndrome
Ocular mesodermal dysplasia (eg, Axenfeld or Rieger anomalies)
Homocystinuria
Aniridia
Acquired glaucoma (rare)

Pathophysiology:

obstruction of canal of Schlemm located between cornea + iris leads to decreased resorption of aqueous humor (= anterior chamber fluid) with scleral distension

[check mark] uniformly enlarged globe without mass of round/oval/bizarre shape

Rx: goniotomy (increases the angle of anterior chamber); trabeculotomy (lysis of adhesions)

CAROTID-CAVERNOUS SINUS FISTULA

= abnormal communication between veins of cavernous sinus + ≥1 branches of internal/external carotid artery

Etiology:

Trauma: laceration of ICA within cavernous sinus
- usually secondary to basal skull fracture (cavernous ICA + small cavernous branches fixed to dura)
- penetrating trauma
- surgery
Spontaneous: rupture of an intracavernous ICA aneurysm (in atherosclerosis, Ehlers-Danlos syndrome, osteogenesis imperfecta, pseudoxanthoma elasticum)
Dural sinus thrombosis
Atherosclerosis

Age: middle/late adulthood; M <A onclick="get_content(event,'AB8-M1'); return false;" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title="< F

Route of drainage:

superior ophthalmic vein (common)
contralateral cavernous sinus
petrosal sinus
cortical veins (rare)

classic triad:
- pulsatile exophthalmos
- conjunctival chemosis/edema
- persistent auscultatory orbital bruit
restricted extraocular movement
decrease in vision due to increase in intraocular pressure (50%)/cranial nerve deficits = indication for emergent treatment

enlarged edematous extraocular muscles
dilatation of superior ophthalmic vein, cavernous sinus, facial veins, internal jugular vein
focal/diffuse enlargement of cavernous sinus
occasionally sellar erosion/enlargement
enlargement of superior orbital fissure (in chronic phase)
stretching of optic nerve
proptosis

US:

arterial flow in cavernous sinus + superior ophthalmic vein

MR:

flow voids in cavernous sinus

Angio:

ipsilateral ICA contrast injection shows wall of ICA to be incomplete
contralateral ICA contrast injection + compression of involved ICA
early opacification of veins of cavernous sinus
retrograde flow through dilated superior ophthalmic v.

Rx: latex/silicone balloon detached inside cavernous sinus to plug laceration (ocular signs resolve within 7-10 days)

CHOROIDAL DETACHMENT

= fluid accumulation in potential suprachoroidal space separating choroid from sclera with sparing of optic disc due to anchoring effect of short posterior ciliary arteries + veins + nerves

Cause: trauma (accidental perforation), inflammation (uveitis), surgical intervention, spontaneous

Pathomechanism: ocular hypotonia → decreased pressure in suprachoroidal space → accumulation of serous/hemorrhagic transudate

US:

two convex lines projecting into the eye from periphery of globe + advancing to ciliary body with posterior fixation outside the optic disc (= macula)
minimal/no choroidal membrane mobility during eye movement

CHOROIDAL HEMANGIOMA

= congenital vascular hamartoma

Mean age: 31 (range, 7-58) years (most common benign tumor in adults); M÷F = 1÷1

May be associated with: Sturge-Weber syndrome

Classification: capillary/cavernous/mixed

Location: posterior to equator, temporal to optic disc (70%)

• smoothly elevated slightly dome-shaped reddish-orange choroidal mass

lenticular mass of 7.5 (range, 3-11) mm
intense enhancement similar to choroid
focal thickening of posterior wall of globe

CT:

ill-defined mass with intense enhancement

MR:

hyperintense to vitreus on T1WI (rule)
isointense to vitreus on T2WI (rule)

US:

hyperechoic homogeneous mass

DDx: uveal melanoma (choroidal excavitation)

Cx: retinal detachment (frequent)

Rx: usually none; photocoagulation with retinal detachment

CHOROIDAL MELANOMA

Prevalence: 5-7÷1,000,000; white÷black = 15÷1

♦ Most common primary intraocular tumor in adults
♦ Most common uveal melanoma (choroid ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> iris ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> ciliary body)

Age: 65% in >50 years of age

initially flat growth profile, later becoming elevated, erupting through Bruch membrane to a characteristic mushroom shape
moderate to strong contrast enhancement

Metastatic to: liver ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> lung ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> bone ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> kidney ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941992c6d97a44cbf92d6b4115f238e1826376bacbe7dc1f6542b2ee8833965d32e7cafd91a39ee5a210}/ID(AB9-M1)”>> brain

MR:

well-defined solid mass (unless hemorrhagic/necrotic)
paramagnetic effect of melanin:
- increased signal intensity on T1WI
- decreased signal intensity on T2WI
amelanotic + slightly melanotic melanoma:
- isointense on T1WI
- slightly hypointense on T2WI

CHOROIDAL OSTEOMA

= rare juxtapapillary tumor of mature bone

Age: young woman

Location: may be bilateral

[check mark] small flat very dense curvilinear mass aligned with choroidal margin of globe

DDx: calcified choroidal angioma

COATS DISEASE

= RETINAL TELANGIECTASIA = PSEUDOGLIOMA

= congenital nonhereditary primary vascular malformation of the retina characterized by multiple abnormal telangiectatic retinal vessels with aneurysm formation

Pathogenesis:

lack of blood-retina barrier at level of endothelial cells → leakage of a lipoproteinaceous exudate of cholesterol crystals into retina + subretinal space → detachment of retina → progressive obliteration of vitreous space

Peak age: 6-8 years (range, 5 month — 75 years); M÷F = 2÷1

strabismus
may present with leukokoria (if retina massively detached = 16% of leukokoria cases)
strabismus, secondary glaucoma, loss of vision
cholesterol crystals at funduscopy

Location: unilateral in 83-95%

Associated with: retinal detachment, slight microphthalmia

normal-sized/slightly smaller globe
NO focal mass/calcification (HALLMARK)

US:

clumpy particulate echoes in subretinal space (due to cholesterol crystals suspended in fluid)
vitreous + subretinal hemorrhage (frequent)

CT:

unilateral dense vitreus (due to proteinaceous subretinal exudate)
linear V-shaped enhancement at anterior margin of subretinal exudate (due to thickened retina composed of telangiectatic + aneurysmal vessels

MR:

subretinal exudate hyperintense on T1WI + T2WI (due to mixture of protein + lipid)
heterogeneous hypointensity on T2WI (with hemorrhage + fibrosis)
mild to moderate linear enhancement of retina at ora serrata + of detached retinal leaves

Cx: cataract, painful glaucoma, phthisis bulbi

Rx: photocoagulation/cryo-/laser ablation to obliterate telangiectasias (in early stages); enucleation

DDx: (1) Persistent hyperplastic primary vitreus (thick tubular retrolental mass)

(2) Retinopathy of prematurity

(3) Unilateral noncalcifying retinoblastoma (before 3 years of age, no microphthalmia)

COLOBOMA

[koloboun, Greek = to mutilate]

= incomplete closure of embryonic choroidal fissure affecting eyelid/lens/iris/choroid/retina/macula; autosomal dominant trait with variable penetrance (30%) and expression;

bilateral in 60%

Time of insult: 6th week of GA

May be associated with: encephalocele, agenesis of corpus callosum

Location: in 50% bilateral