- Degenerative – Insertion of muscle tendons, trochlea calcification (associated with DM, may be symptomatic = Brown syndrome), cataracts, phthisis bulbi, retinal detatchment, retrolental fibroplasia, optic disk drusen (punctate calcification at junction of optic nerve and globe).
- Neoplasms – Retinoblastoma, astrocytic hamartoma, NF, TS, VHL, choroidal osteoma.
- Infection – CMV, herpes, rubella, syphilis, toxoplasmosis, TB.
- Hypercalcaemia – CRF, HPT, hypervitominosis D, milk-alkali syndrome, sarcoidosis.
Leukokoria (white pupil) – From opaque tissue interupting light through globe.
- Congenital cataract
- Retinopathy of prematurity (ROP)
- Chronic retinal detachment with ROP
- Choroidal haemangioma
- Retinal astrocytoma
- Persistent hyperplastic primary vitreous (PHPV)
- Coats disease
- Toxocaracanis infection
Acute glaucoma from anteior hyphema, lens dislocation, scarring of canals of Schlemm.
Vitreous haemorrahge from trauma, diabetic retinopathy, sickle cell, post-vitreous detachment, HIV related CMV infection, retinal vein occlusion.
Myopia cuases elongation of the globe.
Papilloedema – Oedema of the head of optic nerve, from compression of the nerve or elevation of CSF pressure around the nerve. The increased pressure causes venous stasis leading to nerve head swelling. Straightening or reverse cupping on imaging.
Intercompartmental disease from orbital pseudotumour, metastases, haemangioma, lymphoma, chloroma.
Normal optic nerve diameter (OND) is 2.5-4mm. Normal optic nerve sheath diameter (ONSD) is 4-6mm.
Retrobulbar fat stranding from rupture of small vessels. True haematoma is uncommon as blood diffuses throughout the orbit; may occur in the intraconal space, subdural within nerve sheath, extraconal space, subperiosteal, subtenon space (between sclera and Tenon’s capsule). Most commonly orbital roof, more seen in younger patients. May resolve or evolve into hematic cysts (cholesterol granuloma). Optic nerve sheath haematoma – hyperdense mass enclosed by sheath; may cause ischaemia under pressure, surgical emergency requiring drainage. Retrobulbar haemorrahge may raise intraorbital pressure causing central retinal artery occlusion or opitic nerve ischaemia.
May be associated with orbital subperiosteal haematoma. Haematoma of orbital muscles may reduced ROM.
- Medial wall (lamina papyracea) – Orbital emphysema, opacification of ethmoid air cells. Displacement usually minimal, muscle entrapment unusual.
- Linear orbital floor fracture – Rarely associated with entrapment.
- Blowout fracture (comminuted orbital floor fracture) – May be isolated, from direct blow to eye acutely increasing intraorbital pressure relieved by the fracture. In pure blowout fractures the orbital rim remains intact. Associated with herniation of contents. Inferior rectus entrapment causes vertical diplopia. Mild/transient diploplia may be from periorbital oedema/haemorrhage. Orbital emphysema, antral fluid level, indistinct orbital floor, prolapsed soft tissue in superior antrum, bony spicule/fragment in antrum. May be hinged on medial aspect causing trapdoor fracture, or if fracture splits the floor is ‘bomb-bay door’ fracture. Best seen on prone coronal CT as on supine antral debris will layer against the orbital floor obscuring soft tissue herniation. More urgent repair if >50% orbital floor fractured (causes enophthalmos), diplopia, significant soft tissue entrapment. Entrapment may cause Volkmann-type ischaemic contracture from ischaemia and fibrosis.
- Blow-in fracture – Rare, from direct blow to maxillary sinus. Fragments from orbital floor buckle upwards, may cause proptosis and reduce ROM. Require surgery.
- Orbital roof fracture into frontal sinus – Weaakest point near superior orbital fissure and optic canal. May cause meningocoele (DDx resolving haematoma/seroma) with communication to subarachnoid space.
- Orbital rim fracture – Indicates more severe injury, esp superior rim associated with intracranial injury.
Best seen on CT. MR has the potential of moving ferromagnetic metal.
Ruptured/Perforated Globe and Ocular Hypotony
- Ocular hypotony – Low intra-ocular pressure from surgery, ruptured globe, glaucoma therapy, uveitis/scleritis; causes uveoscleral infolding (flat tire or umbrella sign). Tx injection of saline, silicone oil or sodium hyaluronate. May be associated with serous or haemorrhagic choroidal detachment.
- Double perforation – Perforation through anterior and posterior globe (esp BB-sized shot), unable to be repaired.
- Perforated anterior chamber – Flattening of space anterior to lens (need to compare with other eye).
- Acute traumatic cataract – From acute oedema (hypodense cf senescent cataract hyperdense), may have ill-defined borders.
- Lens dislocation/subluxation – May be dislocated into anterior chamber (may cause acute glaucoma) or vitreous cavity.
Ocular Haemorrhage and Detachment
- Anterior hyphema – Haemorrhage in anterior chamber from globe rupture. Bleeding from iris or ciliary body vessels. May rebleed as clot retracts after 2-5/7. May cause acute glaucoma.
- Posterior vitreous detachment – Separation of the posterior hyaloid membrane from the sensory retina. Thin curvilinear/semilunar, separate from optic disc with variable extension. May be associated with macular degeneration, PHPV.
- Retinal detachment/separation – Separation of inner neurosensory and outer retinal pigment layers of retina (subretinal space). V shaped with apex to optic disc and arms at ora serrata. May be associated with retinoblastoma, Coats dsieases, Toxocara, diabetes, melanoma, choroidal haemangioma, trauma, senile macular degeneration, PHPV.
- Choroidal detachment – Limited by vortex veins or posterior ciliary aa, don’t usually reach optic disc, may extend beyond ora serrata to ciliary body. From ocular hypotony, trauma, surgery, uveitis/scleritis, melanoma.
- Serous detachments are benign, linear, cresenteic or ring-shaped density. Inflammatory choroidal effusions (from uveitis, posterior scleritis) may be high density, may change with head position. High T1 and T2.
- Haemorrhagic detachments are convex, dense, don’t change with position. Implies ruptured choroidal vessel with poor prognosis.
- Subtenon space haemorrhage – Between sclera and fibrous Tenon capsue, conforms to shape of the eyeball.
Traumatic Optic Neuropathy
May be maximal initially or delayed worsening from secondary optic nerve compression (oedema/haemorrahge). CT to detect fracture through optic canal or orbital apex; these rarely cause the injury, but evidence severe stress transmited to orbital apex. Primary optic nerve injury may be from deceleration strain damaging delicate meningeal vessels or direct neural disruption. Optic nerve avulsion is uncommon, no treatment, permanent blindness.
Inflammation and Infection
(Idiopathic orbital inflammation, orbital inflammatory syndrome). Lymphocytic infiltrate. Most common adult intraorbital mass. Often rapidly developing with painful proptosis, chemosis (swelling/oedema of conjunctiva), opthalmoplegia. Usually unilateral (10% bilateral). 10% associated with other disease (multifocal fibrosclerosis) including Wegener granulomatosis, polyarteritis nodosa, sarcoidosis, Lyme disaese, other autoimmune diseases. Diffusely infiltrating, may affect some or all of the orbital elements, including lacrimal gland (sclerosing dacryadenitis), extra-ocular muscles (orbital myositis) and/or Tenon’s capsule (posterior scleritis). May have subtle increase in orbital fat density (dirty fat) or optic nerve thickening. When involving muscles also involves tendinous insertion on the globe (cf thyroid ophthalmopathy). Occasionally involves the globe with uveitis, keratitis (cornea), retinitis, scleritis, episcleritis. Low T1 and T2, enhances, low ADC. DDx sarcoidosis, lymphoma. Tx steroids. Chronic progressive fibrosis form has mild/poor response to steroids, may have intracranial extension, may require chemotherapy or radiotherapy.
Periorbital and Orbital Cellulitis
- Periorbital/preseptal cellulitis – Swelling of eyelids, conjunctivitis. No visual loss, proptosis, chemosis or limited eye ROM. May see superficial abscess, infected sebaceous cyst or dermoid/epidermoid, dacrocystitis or stye (eyelid folliculitis). Tx oral ABs.
- Orbital/postseptal cellulitis – Spread into postseptal space posterior to orbital septum. Painful ophthalmoplegia, proptosis, chemosis, reduced visual acuity, may cause permanent visual loss. From sinus infection, bacteremia, skin infection, foreign body. CT better at determining underlying cause. May cause episcleritis/scleritis (thickened posterior scleral margin), EOM myositis (enlargement and enhancement), subperiosteal collection (esp medial wall adjacent to ethmoid sinuses from rhinosinusitis) or orbital abscess (focal ring-enhancement or gas). May cause orbital vein thrombosis, extending into cavernous sinus. Occasional frontal epidural abscess, subdural empyema or intraparenchymal abscess with high mortality.
Inflammation of the optic nerve causing acute visual deficit (blurring). 20% of patients with MS initially present with this, occus in 80% of MS, 50% of those isolated optic neuritis have MS. May also be due to demyelination or inflammation from infection (sinusitis, TB, viral eg herpes/CMV, syphilis, toxoplasmosis), sarcoid, Lyme disease, SLE or radiotherapy. High T2 and enhancement (perivenous inflammation) of optic nerve which is usually normal in size. Best seen on coronal FS/STIR.
MS optic neuritis is usually unilateral, intraorbital/canulicular segments.
NMO ON usually longer length, cisternal/chiasm/optic radiations, bilateral.
(Thyroid opthalmopathy, Graves disease, thyroid eye disease). Common, F>M, usually asymptomatic inflammatory infiltrate of orbital muscles and connective tissues. Subacute onset over months-years. 10% don’t have evidence of hyperthyroidism (euthyroid ophthalmopathy), otherwise may be hyperthryoid or secondarily hypothyroid. Enlarged extraocular muscles with sparing of tendionous attachments to the globe (cf pseudotumour), increased orbital fat, may have swelling of lacrimal glands and eyelids (significant enlargement should suggest other eg sarcoidosis, lymphoma). Muscles involved in sequential order and decreasing frequency – I’m slow: Inferior, Medial, Superior, Lateral rectus, Oblique. 80% bilateral. In 10% extraocular muscles normal; exophthalmos due to increased retrobulbar fat (DDx steroids, Cushing disease). Progresive optic neuropathy in 5% from prolapse of fat through superior orbital fissure or orbital apex compressing nerves, may cause enlarged superior ophthalmic vein; patients tend not to have significant proptosis ?relative inelasticity. Late optic nerve thickening, bony erosion.
- Toxocara Canis – Infection from child ingesting dog faeces with ova of nematode T.canis, hatches in GIT then migrates through body. Larvae within eye die after months-years causing inflammatory reaction, vitreous opacification, retinal detachement. Usually unilateral. No calcification. Thick enhancement of the sclera. High T1 and T2. Normal size of globe. Raised antibody titers.
- Cytomegalovirus (CMV) – Haemorrhagic opportunistic infection of retina and choroid (esp AIDS). Retinitis causes retinal detachement.
- Herpes Zoster Ophthalmicus – Vesicular eruption along V1 skin around eye (ophthalmicus) or ear (oticus) in immunosuppresed (esp <45yo HIV) or immunocompetent (usually elderly). May spread along optic nerve and vessels causing infarction of the nerve
Infectious or autoimmune (collagen vascular diseases, sarcoidosis), acute or chronic. Thickened enhancing posterior sclera and uvea, may be nodular or diffuse. May be associated with retinal/choroidal detachment.
Focal thinning of cornea/sclera, lined by uvea. Most congenital or associated with high myopia, may be from infection/inflammation or trauma. Nonenhancing outwards bulging of the eye.
Inflammation of choroid, ciliary body, and/or iris. Most idiopathic, others viral (esp herpes), bacteria (eg TB), fungi, parasites (T.gondii), sarcoidosis, collagen vascular diseases (ankylosing spondylitis, Reiter syndrome, RA/JRA, IBD, psoriasis, lupus), trauma. May see enhancement on high resolution MR.
Orbit involved in 25%, but isolated orbital disease is rare. May involve uveal tract, optic nerve sheath (may extend to chiasm), lacrimal gland. Low/intermediate T2, almost always enhances. Characterstic skip lesions along optic nerve.
Granulomatous inflammation, necrosis and vasculitis, high antineutrophil cytoplasmic antibodies (ANCA). 50% involve orbit, primary orbital disease or spread from paranasal sinuses. May case keratitis and scleritis, proptosis, erythematous eyelid oedema, limited EOM ROM, bone destruction, associated sinus disease, nasolacrimal obstruction, dacrocystitis, leptomeningeal thickening and enhancement. Anterior segment usually involved more than posterior. Low T2, homogeneous enhancement.
Persistent Hyperplastic Primary Vitreous (PHPV)
Retained embryonic hyaloid vascular system causing neonatal leukokoria, microphthalmia, small lens with flattening of anterior chamber. Funnel/S-shaped mass of fibrovascular tissue (including persistent hyaloid a) between lens and optic nerve (Coquet’s canal). Prone to haemorrhages. Increased density in globe with enhancement. Doesn’t calcify (cf retinoblastoma). May have blood-vitreous layer from posterior hyaloid detechment.
Vascular anomaly of retina, usualy unilateral. May cause strabismus, leukokoria, usually 6-8yo, M>F. Vessels leak serum and lipid into retina and subretinal space (lipoproteinaceous effusion), may cause retinal detachment. Dense vitreous high T1 and T2, enhances along leaves of detached retina and at sites of retinal insertion. Calcification rare.
- Choroidal haemangioma – Hamartoma in middle-aged and elderly. Circumscribed/solitary or diffuse angiomatous (associated with Sturge-Weber or facial nevus flammeus). Iso/hyper T2. Avid enhancement.
- Capillary haemangioma – <1yo, usually diagnosed within 1st week of life. May affect skin, SC tissue and or orbit. True neoplasm with growth/proliferative phase lasting months (may be rapid), usually plateau at 1-2yo, then involutional phase lasting years, usually disappearing by adolescence. Infiltrative (not circunscribed) soft tissue with multiple flow voids. IC and/or EC. Enlarges with Valsalva.
- Cavernous haemangioma (venous vascular low-flow malformation) – Congenital dilated endothelium-lined vascular channels with fibrous pseudocapsule. F>M, IC (occasionally conal or EC), 30s-40s with insidious painless proptosis and visual disturbance, rapid growth during pregnancy. Sharply circumscribed, round/oval, diffuse occasionally mottled enhancement peripheral->central, occasionally bony orbit expansion, phleboliths. No flow voids.
Venous malformation with enormously dilated veins, intermittent proptosis, retrobulbar pain. Congenital or acquired after trauma, intracranial AVMs, CCF. Hyperdense intraconal mass, increasd with Valsalva. May be single dilated vein or multiple varicosities.
(Lymphatic vascular low-flow malformation). Congenital dysplastic vascular (lymphatic or venous) channels, loose connective tissue and smooth muscle. Any orbital space, not well encapsulated. 3-15yo. Tend to bleed, acute haemorrahge may cause marked expansion with proptosis. Multiloculated, lobular, heterogeneous (blood degradation products), fluid levels, phleboliths. Mixed venolymphatic vascular anomalies may have venous and/or lymphatic connections.
Caroticocavernous Fistula (CCF)
Direct communication between intracavernous ICA and the cavernous sinus. From trauma (most), or ruptured cavernous ICA aneurysm (usualy elderly), osteogenesis imperfecta, Ehlers-Danlos, pseudoxanthoma elasticum. Pulsating exophthalmos, orbital bruit, glaucoma, enlarged extraocular muscles. Unilateral superior ophthalmic vein enlarged (cf bilateral in raised ICP) or thrombosed (irregular or absent enhancement), periorbital swelling, ill-defined margins of the globe (conjunctival oedema). Cavernous sinus distended with convex margin. Reversal of blood flow. Angiogram shows early filling of opthalmic vv, petrosal sinuses, cortical veins, may be bilateral (intercavernous connections).
Dural Arteriovenous Fistula (DAVF)
Ischaemic Optic Neuropathy
- Anterior ischaemic optic neuropathy (AION) – Arteritic type usually associated with vascular risk factors, more severe visual loss, uni/bi-lateral, may be associated with retinal ischaemia; usually from giant cell arteritis or other arteritides. Nonarteritic is usually unilateral. End stage optic atrophy.
- Central retinal artery occlusion (CRAO) – Usually atherosclerotic thromboembolism, may be from GCA or other arteritides. Secondary degeneration of optic nerve axons from damaged retinal ganglion cells.
Optic nerve atrophies, bight T2. DDx congenital optic nerve hypoplasia, macropthalmos, compressive lesions (pituitary tumours, craniopharyngioma), herpes zoster, MS, trauma, glaucoma.
Most common paediatric ocular malignancy, almost all <3yo. From neuronal cell origin. Leukokoria, strabismus, reduced vision, retinal detachment, glaucoma, ocular pain. 60% sporadic; 40% inherited AD retinoblastoma gene (RB1) on chromosome 13, of which 1/3 are bilateral, associated with other nonocular tumours esp pineoblastoma (trilateral retinoblastoma), osteosarcoma. May spread into subarachnoid space via optic nerve, haematogenous or lymphatics. Calcified (in 95%) mass in posterior globe, extending into vitreous. Minimal enhancement. Enlarged optic nerve from invasion. Moderately high T1 (?calcium, tumour protein or haemorrhagic component), low T2. Classification group A <3mm; B >3mm confined to retina; C localised to vitreous or subretinal; D diffuse vitreous or subretinal seeding; E anterior segment, ciliary body, no vision, neovascular glaucoma, vitreous haemorrahge or phthisis bulbi.
Most common adult ocular malignancy. Unknown aetiology ?increased risk with UV light. High T1, low T2 due to free radicals that exist in melanin. Amelanotic melanomas are low T1, high T2/PD. Hyperdense, enhance. May have associated retinal detachment. Classically collar-button shape with waisting as it ruptures through Bruch’s membrane (innermost layer of uvea/choroid). May have episcleral spread, metastases to liver (usually 1st) and lung.
(Formally dictyoma). From primitive nonpigmented epithelial lining of ciliary body. Children and adults. High T1, low T2, 25% calcify. Benign or locally invasive, rarely metastasizes.
- Ocular metastases – From breast, lung, lymphoma, leukaemia. Tend to cause eccentric thickening of uveoscleral rim, retrobulbar extension. Usually initially flat. Choroidal lymphoma and leukaemia similar to uveal melanoma, but may be bilateral (rare in melanoma).
- Retrobulbar metastases – Usually EC, most have bony involvement. Most breast or lung. Enophthalmos characteristic of scirrhous breast cancer. In children may be neuroblastoma (hyperdense arising from bone) or Ewing sarcoma (esp sphenoid wing).
Benign, young women. Unifocal ossification, juxtapapillary with punctate calcification at posterior pole, usually temporal to optic nerve.
Visual Parthway Glioma
90% <20yo, F>M; those arising in adults are usually malignant. Associated with NF1 in 25%, esp when bilateral. Low grade pilocytic astrocytomas. 4x more common than meningiomas. Growth phase in childhood then usually stabilizes. 33% confined to intraorbital optic nerve, 25% intraorbital and intracranial optic nerves, 15% intracranial nerve or chiasm alone, rest along remainder of visual pathway. Enlarged tortuous optic nerve, iso T1, iso/high T2, variable enhancement. May have fusiform high T2 perioptic meningeal thickening (peritumoral reactive meningeal change = arachnoidal hyperplasia/gliomatosis) surrounding the lower signal gioma, esp NF. In non-NF nerve tends to be fusiform, NF diffusely enlarged and tortuous. Non-NF (sporadic) optic glioma tend to be more rounded, more C+ and worse prognosis. May have cystic components from ischaemia, radiation or mucin. Remodelling and enlargement of the orbital apex. Calcification rare unless previous radiotherapy. Chiasm gliomas commonly extend into hypothalamus with higher morbidity/mortality.
Primary or secondary (esp NHL MALT). Older patient with slowly progressing painless proptosis. Diffusely infiltrating, may extend into any retrobulbar structure. Tend to be superior, molds to contour of the orbit with bony destruction and extension beyond orbit uncommon. DDx pseudotumour.
Optic Sheath Meningioma
Primary optic nerve meninges or extension from cranial meninges (planum sphenoidale or tuberculum sellae). Slowly progressive visual loss (cf gliomas usually stable). Cylindrical along nerve with ‘tram track’ or sandwich sign, doughnut on coronal, peripheral optic nerve enhancement (sheath rather than nerve; DDx pseudodumour, sarcoid, leukaemia or lymphoma, metastases in perioptic nerve sheath CSF space); fusiform or globular. Nerve seen separate to the mass. Rarely bilateral (usually extension from intracranial meningioma or NF2). May invade through dura, being irregular and asymetric (cf gliomas). Hyperdense, iso/high T1, slightly high T2 enhancing, adjacent bony erosion or hyperostosis. Enhancement may be feathery cf smooth contour of gliomas. Calcification in 20-50%.
Schwannomas, neurofibromas and amputation neuromas of the CN 3/4/5/6, sympathetic/parasympathetics or ciliary ganglion. Schwannomas have cystic and enhancing solid components. Neurofibromas are unencapsulated (less defined), being localised, diffuse or plexiform.
90% <16yo, most common malignant orbital tumour in childhood, usually IC and EC involvement. Rapidly progressive painless proptosis. From primitive orbital mesenchymal elements or secondary from EOM/nasopharynx/sinuses. Irregular, homogeneous, well-defined, uniform enhancement. May appear like cluster of grapes. Bone destruction in 40%. Common preseptal extension.
Dermoid and Epidermoid
Congenital rests. Usually extraconal esp superolateral, occasionally within lacrimal gland. May have dermal sinus tract that can be superinfected. May rupture inducing granulomatous inflammation and scarring.
Most lacrimal gland lesions do not have specific findings.
- Inflammatory lesions – Sarcoidosis, Sjogren syndrome, dacryoadenitis (esp EBV). Well-defined enlargement and enhancement.
- Epithelial tumours include same lesions arising in salivary glands.
- Pleomorphic adenomas – Benign, cystic spaces, may have bony remodelling, small amounts of calcification.
- Malignant adenoid cystic carcinoma – Commonly involves bone, perineural spread into cavernous sinus.
- Lymphoid tumours – Lymphoma and pseudotumour.
Lacrimal sac lesions:
- Dacrocystitis – From obstructed nasolacrimal duct, may be due to congenital lack of canalisation of the valve of Hasner (lower end of nasolacrimal duct). Dacryocele (dacrocystocele) – cystic mass at the medial canthus. Enhancement of dilated lacrimal sac.
- Tumours – Uncommon, include SCC, TCC, papilloma.
Shrunken non-functional eye after end-stage severe ocular disease/inflammation/injury, with internal disorganisation. Eye may become squared due to hypotony (reduced intra-ocular pressure) and pull of extra-ocular muscles. May be calcified.
Mucoprotein matrix at optic nerve head (disc) with laminated calcium. 2% of population. May be familial (usually bilateral) or associated with eg retinitis pigmentosa. May cause pseudopapilloedema.
Congenital defect in any ocular structure. Atypical colobomas in iris. Typical colobomas are cone-shaped or notch deformity inferomedial posterior globe from incomplete closure of choroidal fissure, may cause elongated/malformed globe or ocular cyst, may involve optic nerve, eversion of postion of posterior globe. No scleral thinning (cf staphyloma). May be associated with orbital cysts, midline craniocerebrofacial clefts (sphenoidal encphalocele, callosal dysgenesis, olfactory hypoplasia, cardiac abnormal etc), CHARGE syndrome (coloboma, heart defects, atresia or the choana, retarded growth and development, ear anomalies).
Retinopathy of Prematurity (ROP)
Prolonged oxygen in premature infants. May cause bilateral leukokoria, traction retinal detachments, posterior globe calcification.
Porous ocular prosthesis after enucleation. Intermediate intensite on all sequences, variable enhancement representing fibrovascular ingrowth. Nodular/infiltrating enhancement around the implant suggests recurrent tumour or inflammation.
Posterior globe conical/tented from retrobulbar mass causing proptosis and stretching of optic nerve.
Post-Transplatation Lymphoproliferative Disorder (PTLD)
In 2-3% of organ transplant patients, usually in 1st year. EBV-induced B-cell proliferation esp lacrimal gland. Enhancing soft tissue mass with destruction of bone (cf lymphoma), often extends intraconally.