the orbit

The Orbit

Anatomy
The Roof : Frontal bone, Lesser wing of sphenoid
The Lateral wall : Greater wing of sphenoid, Zygomatic
The floor : Maxillary, Zygomatic , Palatine
The medial wall : Maxillary, Lacrimal , Ethmoid , Sphenoid.

Functions

Protection to the eye ball
Provide attachments to the ligaments which stabilize the eye ball

Clinical features of orbital lesions

Abnormal Displacement of The Eye Ball

Proptosis

Abnormal protrusion of the eye ball

Distance between lateral orbital rim and the apex of the cornea is more than 20mm, or difference of 2mm between the two eyes is suspicious.







Axial proptosis :
axial displacement of the eyeball
Space occupying lesion inside the muscle cone

Optic nerve glioma
Thyroid dysfunction:Exophthalmus

Eccentric proptosis:

non-axial displacement of the eye ball
space occupying lesion outside the muscle cone

Tumors of the lacrimal gland

Enophthalmos:

Backward displacement of the eye ball
Orbital fracture with herniation of the orbital contents .

Causes

• a- Small globe, congenital anomaly e.g. microphthalmos or nanophthalmos
• b- Structural bony abnormalities
• c- Atrophy of orbital contents
• d- Cicatrizing orbital lesions

Clinical features of orbital lesions

Pain
Inflammatory or infective conditions

Ophthalmoplegia:

Impairment of extraocular movement
Causes
Inflammation (myositis)
Fibrosis (thyroid dysfunction)
Tethering of the muscles (blow out fractures)
Paralysis (ocular motor nerves lesions).

Impairment of Vision

• Exposure keratopathy secondary to proptosis
• Optic nerve dysfunction
diminished pupillary light reflex
acute stage; optic nerve congestion, swollen
chronic stage; secondary optic disc atrophy

Investigations

X-ray
C.T. scan
MRI


Orbital Cellulitis
Vision threatening and can be life threatening condition
Infection of the soft tissue of the orbit
mostly by bacteria
Strep. pneumoniae, Staph. aureus, H. influenzae.

Causes; 1-spread of microorganisms from the

adjacent structures, paranasal sinuses
2-Post traumatic

Clinical features:

Symptoms
Rapid onset
Fever , malaise
Pain
Impairment of vision
Signs
Lid swelling,
Conjunctival congestion
Proptosis
Ophthalmoplegia
Optic nerve dysfunction

Complications;

Cavernous sinus thrombosis
Orbital abscess
Brain abscess

Management

Hospital admission
Antibiotic therapy; started immediately with broad spectrum antibiotics
Third generation Cephalosporins+ metronidazole

Dysthyroid Ophthalmopathy

Autoimmune disorder usually associated with abnormal thyroid function
Pathogenesis;
Hypertrophy of extraocular muscles
Deposition of glycosaminoglycans
Infiltration with mononuclear cells, macrophage

Clinical features

1-Exophthalmus; most common cause of unilateral and bilateral
proptosis
2-Conjunctival hyperemia and edema
3-Lid retraction
4-Lid lag
5-Ophthalmoplegia
6-Optic nerve neuropathy

Orbital TumorsDermoid

Benign cystic teratoma,
Growth of displaced ectodermal tissue at subcutaneous location
Presentation: during infancy
Painless nodule at the upper temporal or upper nasal angle of the orbit
Firm non tender, smooth surface, freely mobile under the skin

Orbital Tumors Capillary haemangioma

Most common benign tumor of the orbit. Vascular hamartoma
Presentation: during perinatal period
Location:
Skin, Strawberry swelling on the eyelid
Subcutaneous
fornix conjunctiva
deep in the orbit causing proptosis
Course; 70% spontaneous resolution at age 7 years.
Treatment; for large lesions,beta blocker, local injection of steroids

Orbital Tumors

Optic nerve glioma

Meningioma
Lacrimal gland tumors
Rhabdomyosarcoma; commonest orbital tumor in children

Carotid-cavernous fistula:

Abnormal communication between internal carotid artery and cavernous sinus

Causes; rupture congenital aneurysm or post traumatic

Clinical features;
Congested vessels,
Chemosis,
Hyperemic disc,
Pulsating exophthalmus

Examination for proptosis

Inspection
Exophthalmus
Thyroidectomy scar
Palpation
Orbital margin
Retropulsion
Measurement
Amount of proptosis
Margin reflex distance
Observe eye movement
Lid lag
Restrictive eye movement

Additional test

Check RAPD
Check colour vision
Check V.F
Perform fundoscopy
Listen with the bell if CCF is suspected