Orbit

Question 1

Anatomy

Answer 1

1. Pear shaped bony cavity with the optic canal as the stalk of the pear.
2. Paranasal sinuses lie inferior+ medial; lateral is the temporal fossa and superior the cranial cavity.
3. Orbit lies behind orbital septum and has a roof, a floor, medial and lateral walls and an apex.
4. Orbital conditions: adjacent structures in
   addition to the structures that lie within the orbit.

Question 2

Clinical examination

Answer 2

All patients with suspected or confirmed orbital pathology must be evaluated by an ophthalmologist
HISTORY
1. Main characteristics of orbital conditions:
(a) Proptosis or enophthalmos
(b) Pain
(c) Decreased vision
(d) Diplopia
2. The two most valuable symptoms are the presence of pain and the mode of onset of the proptosis.
Examples:
(a) Slow, painless onset of proptosis ⇒ benign tumour.
(b) Rapid, painful onset of proptosis in a child ⇒ orbital cellulitis or rhabdomyosarcoma.
(c) Rapid, painful onset of proptosis in an adult ⇒ orbital cellulitis or pseudotumour.
3. Always specifically ask about:
(a) Malignancies
(b) Thyroid dysfunction
(c) Orbital trauma
(d) Sinusitis

EXAMINATION
1. Exclude pseudoproptosis
(a) Enlargement of the eye itself, eg. buphthalmos,
high myopia.
(b) Contralateral enophthalmos.
(c) Eyelid retraction.
(d) Shallow orbit, eg. craniofacial dysostosis, facial
asymmetry.
2. Always look from above, as differences between the
eyes are more apparent.
3. Note the difference between:
(a) Axial proptosis due to an intraconal space occupying lesion such as a glioma.
(b) Nonaxial proptosis due to an extraconal space occupying lesion such as a lacrimal gland tumour.
4. Measurement of proptosis
(a) The sagittal distance between the corneal apex and the lateral orbital margin is normally < 20mm.
(b) This distance can be measured with a Hertel exophthalmometer or a ruler.
(c) A difference of > 2mm between the eyes is an indication for further investigation.
5 Palpation
(a) Palpate the orbital margin systematically. Know the anatomy. (b) A bony erosion or mass can easily be palpated.
6. Orbital compression
(a) Through gently closed eyelids and using the index fingers of both hands, apply gentle posterior pressure first to the normal and then the abnormal eye, comparing the amount of resistance.
(b) Increased resistance to ocular retropulsion is suggestive of a solid tumour or thyroid
7. Eye movements may be restricted as a result of one of the following:
(a) Restrictive myopathy eg. thyroid ophthalmopathy.
(b) Splinting of the optic nerve eg. meningioma.
(c) A neurological lesion.
(d) A “blow-out” fracture causing muscle entrapment.
8. Visual acuity may be reduced as a result of one of the following:
(a) Optic nerve compression.
(b) Exposure keratopathy.
9. Pupil reactions
An afferent pupil defect is frequently a sign of optic nerve compression and is an indication for
automated visual field testing and for aggressive treatment.
10 Ophthalmoscopy: The presence of a pale or swollen disc is extremely important.
11. Haemodynamic evaluation:
(a) Attempt to engorge the orbital veins by performing one or more of the following:
• Compress the jugularvein.
• Hold their head in a dependent position for a few minutes.
• Valsalva manoeuvre.
The proptosis is aggravated in orbital varices and capillary haemangioma.
(b) Inspect and palpate for ocular pulsation caused by an A V fistula.
(c) Auscultate over the eye or frontal area for a bruit caused by an AV fistula.
The bruit will usually disappear or diminish on ipsilateral carotid artery compression.

Question 3

Special investigations

Answer 3

1. Automated visual fields
2. Orbital ultrasound
3. X-rays
4. CT scan
5. MRI scan
6. Biopsy: open and fine needle

Question 4

Orbital pathology

Answer 4

1. Thyroid opthalmopathology
2. Blow out fracture
3. Cellulitis
   - Presepral
   - Orbital
4. Orbital vascular conditions
   - Orbital Varices
   - Caroticocavernous fistula
5. Orbital tumours
   - Lymphoprolipherative tumours
   Inflammatory Pseudotumour
   - Vascular tumours
   Capillary Haemangioma
   Cavernous Haemangioma
   Lymphangioma
   - Lacrimal gland tumours
   Pleomorphic Adenoma
   Adenosarcoma
   - Rhabdomyosarcoma
   - Cystic tumours
   Dermoid cyst
   Mucocoele
   Hydatid cyst
   - Neural tumours
   Optic nerve Glioma
   Optic nerve sheath Meningioma
   - Metastatic tumours

Question 5

CELLULITIS : PRESEPTAL

Pathophysiology
Presentation
Treatment

Answer 5

PRESEPTAL CELLULITIS
Pathophysiology:
Infection usually secondary to trauma or local skin infection.

Present:
- Periorbital swelling
- Periorbital tenderness
- Infection does not penetrate the orbital
septum –> no proptosis, no impairment of eye movement.

Treatment: oral AB as outpatient basis.

Question 6

ORBITAL VASCULAR CONDITIONS: ORBITAL VARICES

Pathophysiology
Presentation
Treatment

Answer 6

ORBITAL VARICES
Pathophysiology:
- Vascular hamartoma consisting of a plexus of thin walled veins with connections to the normal orbital circulation.

Presents:

1. Intermittent nonpulsatile proptosis
2. pain
3. orbital haemorrhage
4. Signs are associated with bending, coughing and straining at stool.
5. No bruit and it can be precipitated by pressure on the internal jugular vein, a Valsalva manoeuvre and head dependency.

Treatment: conservative.

Question 7

CELLULITIS: ORBITAL

Pathophysiology
Presentation
Complications
Treatment

Answer 7

ORBITAL CELLULITIS
Pathophysiology:
Orbital cellulitis is much more dangerous than preseptal cellulitis and usually arises in the paranasal sinuses, especially the ethmoids.

presents:
- orbital pain
- diplopia
- eyelid oedema
- generalised redness of the eye
- conjunctival chemosis
- proptosis
- limitation of eye movements.

Complications:

• blindness
• meningitis
• brain abscess
• cavernous sinus thrombosis

Treatment

a) admission
b) intravenous antibiotics
c) X-rays
d) CT scan
e) surgical intervention.

Question 8

ORBITAL VASCULAR CONDITIONS: CAROTICOCAVERNOUS FISTULA
DIRECT FISTULA

Direct
Indirect

Pathophysiology
Cause
Presentation
Treatment

Answer 8

DIRECT
Pathophysiology:
Blood shunts from a rupture in the intracavernous part of the internal carotid artery –> cavernous sinus.

Cause:
trauma/ spontaneously in a HPT patient.

Present:
 < vision
generalised redness of the eye
conjunctival
chemosis
pulsatile proptosis 
audible bruit
ophthalmoplegia.

Treatment:
spontaneously resolve/ surgery is required.

INDIRECT FISTULA
Pathophysiology
Communication: meningeal branches of the external or internal carotid aa + cavernous sinus.

Cause:
spontaneously in hypertensive patients

Presentation: More subtle 
< vision
generalised redness of the eye
conjunctival
chemosis
pulsatile proptosis 
audible bruit
ophthalmoplegia.

Treatment:
spontaneously resolve/ surgery is required.

Question 9

LYMPHOPROLIFERATIVE TUMOURS
INFLAMMATORY PSEUDOTUMOUR

Pathophysiology
Presentation
Treatment

Answer 9

Pathophysiology:
Diffuse idiopathic orbital inflammation.

Presentation: Rapid onset of painful proptosis:

• diplopia
• eyelid oedema,
• conjunctival chemosis
• generalised redness of the eye
• limitation of eye movements.

Treatment:

1. observation
2. systemic steroids
3. radiotherapy
4. cytostatics
5. biopsy to distinguish it from other similarly presenting conditions such as lymphoma.

Question 10

VASCULAR TUMOURS

Answer 10

1. CAPILLARY HAEMANGIOMA
   Usually presents at or shortly after birth–> enlarge with crying and may spontaneously disappear by the age of 5 years.
2. CAVERNOUS HAEMANGIOMA
   This is the commonest benign orbital tumour in adults.
3. LYMPHANGIOMA
   Often occurs in children and may suddenly enlarge due to haemorrhage in the lesion,

Question 11

LACRIMAL GLAND TUMOURS

Answer 11

1. PLEOMORPHIC ADENOMA
   Presents:
   - slowly progressive painless swelling in lacrimal fossa.
   - Tumour well encapsulated
   Treatment:
   - removed en-block.
   - Incision biopsy is contraindicated as it may lead to infiltration.
2. ADENOCARCINOMA
   Enlarges rapidly and has a very poor prognosis.

Question 12

RHABDOMYOSARCOMA

Presentation

Answer 12

Commonest primary malignant orbital tumour in children.

Presents:

• 7 years
• rapidly progressive proptosis–> one week
• may be confused with an inflammatory process.

Question 13

CYSTIC TUMOURS

Answer 13

1. DERMOID CYST: Developmental choristoma lined with epithelium and filled with keratinised material.
2. MUCOCOELE: Arises in one of the paranasal sinuses.
3. HYDATID CYST: Must be removed without rupturing the cyst to prevent recurrence.