Orbit Flashcards
Orbit roof
frontal, and lesser wing of sphenoid
Orbit lateral wall
Greater wing of sphenoid bone, and zygomatic
Orbit medial wall
sphenoid, maxillary, lacrimal, ethmoidal
Orbit floor
Zygomatic, maxillary and palatine
Lamina papyracea
paper thin play covering ethmoidal air cells. entry of infection from ethmoidal sinus
Optic forman
optic nerve
ophthalmic artery
Superior ophthalmic fissure (SOF)
Superior: CN 4 + superior ophthalmic vein + lacrimal and frontal nerves (CNV1)
Inferior: CN 3 + 6 + nasociliary nerve (CNV1)
Inferior orbital fissure (IOF)
inferior ophthalmic vein
infraorbital nerve (CNV2)
Zygomatic nerve (CNV2)
Common tendinous ring (Annulus of Zinn)
origin of recti muscles
through: CN 2, 3 and 6 + nasociliary nerve
Thyroid eye disease phases
Active inflammatory phase
Inactive fibrotic phase
Thyroid eye disease risk factors
Smoking
Female
What causes eye lid retraction in TED
Overstimulation of Muller muscle
Complications of glycosaminoglycan deposition into EOM in TED
- Restrictive myopathy
- Exophthalmos - dry eyes and exposure keratitis
- Fibrosis of levator palpebrae
- Optic neuropathy (compression)
- impaired venous drainage - conjunctival and periorbital oedema
Clinical features of TED
- Proptosis
- Lid retraction (Dalrymple sign)
- Lid lag on downward gaze (Von Graeffe sign)
- Staring apperance (Kocher sign)
- Restrictive myopathy: IR>MR>SR>LR
TED investigations
TFTs
CT/ MRI orbit
Visual field testing
Orbital mucormycosis
Fungal infection, gradual onset
Immunocompromised
Fx: orbital swelling and signs of orbital cellulitis, necrotic black eschars over the nose or palate
Orbital cellulitis Ix and Mx
CT scan
IV abx
Preseptal cellulitis mx
Oral abx
Rhabdomyosarcoma
Most common primary orbital tumour in children
Optic nerve sheath meningioma associated with
NF2
Optic nerve glioma
NF1
Direct carotid-cavernous fistula
High flow, between internal carotid and cavernous sinus directly
fx
- pulsatile proptosis
- conjunctival chemosis
- whooshing sound in head
- visual loss, ophthalmoplegia, raised ICP
Direct CCF Ix and Mx
Ix: MRA
Mx: transarterial repair
Indirect carotid cavernous fistula
Low flow, between meningeal branches of the internal/ external carotids and cavernou sinus
spontaneous in hypertensive women
Cavernous sinus thrombosis
Due to spread of infections from para-nasal sinuses, ear or orbital cellulitis
Fx: proptosis, CN3, 4 and 6 palsy, reduced VA,
nausea, vomiting, rapid onset headache, chemosis
Mx: iv abx, steroids
