Diseases of the Orbit

Question 0

Name the four chief clinical features in disease of the orbit.

Answer 0

1. Propotisis (axial vs non-axial proptosis)
2. Visual loss (pressure on optic nerve. Optic disc may be swollen or atrophic. Visual acuity, colour and peripheral vision may be affected).
3. Double vision (diplopia, when eyes misaligned in straight gaze or during movement).
4. Pain (space-occupying effect, or involvement of sensory nerves).

Question 1

True or false: the main clinical features of orbital disease are not specific to the underlying pathology.

Answer 1

True.
The wide range of diseases affecting the orbit share many common features by occupying volume within a small space and damaging specific orbital structures.

Question 2

Best investigation for orbital eye disease?

Answer 2

CT scan.

Question 3

Ocular complications arise from which general thyroid disorders?

Answer 3

Usually hyper- (Graves’ ophthalmopathy), but even in hypo- or euthyroid states.
Ocular complications may precede development of biochemical thyroid dysfunction.

Question 4

Name two main/common ocular complications of thyroid disease and rough mechanism behind them.

Answer 4

1. Proptosis (may be unilateral, may lead to corneal exposure and loss of vision, plus cosmetic nuisance)
2. Double vision (often variable in time and severity).

Caused by infiltration of the orbital tissues by inflammatory cells and oedema, since the underlying pathogenesis is a type 2 hypersensitivity to extraocular muscle antigens.
Visual loss may result from optic nerve compression.

Question 5

What are two less severe ocular manifestations (signs) of thyroid disease?

Answer 5

1. Lid retraction (produces ‘staring’ appearance)

2. Lid lag (jerky downwards movement of upper lid on downgaze).

Question 6

Name four treatments for dysthyroid eye disease.

Answer 6

1. Lubrication
2. Diplopia - Prisms attached to spectacles or sometimes surgery
3. Eyelid surgery - to overcome lid retraction
4. Systemic immunosuppression (eg. Steroids), orbital radiotherapy and surgical orbital decompression (fracturing of the walls of the orbit to allow displacement of orbital contents) for severe proptosis and optic nerve decompression.

Treatment of underlying thyroid dysfunction does not influence the course of ocular disease.

Question 7

Infection within the orbit (orbital cellulitis) is usually associated with an infection where?

Answer 7

In a paranasal sinus.

Question 8

What are 5 ocular signs of orbital cellulitis?

Answer 8

1. Reduced ocular movement
2. Proptosis
3. Redness of eyelids
4. Swelling of eyelids
5. Conjunctival injection

Plus systemic signs of infection possible.

Question 9

What are three causative organisms of orbital cellulitis?

Answer 9

1. H. Influenzae (esp. in young children)
2. S. Pneumonia
3. Anaerobes

Question 10

Why should orbital cellulitis be treated aggressively, and how?

Answer 10

To prevent visual loss and intracranial spread.
Immediately start appropriate IV ABx. Failure to respond despite treatment may indicate development of an orbital abscess, seen on CT.

Question 11

What could be the sequelae of a squash ball to the eye?

Answer 11

Sudden increase in intraorbital pressure which transmits to the thin floor of the orbit (which may fracture). Occasionally the medial wall will fracture.
Once initial haematoma subsides, eye is seen to be displaced backwards (enophthalmos).
Entrapment of orbital tissues within fracture site leads to double vision, especially on up- and downgaze.
Damage to the infraorbital nerve alters sensation on the cheek.

Question 12

How would you manage a squash ball (or similar object) to the eye?

Answer 12

Systemic ABx (for what is, in effect, a compound fracture). 
Surgical mx controversial. Ocular movement may often improve without intervention.

Question 13

What are five main causes of orbital disease?

Answer 13

1. Dysthyroid eye disease
2. Orbital cellulitis
3. Trauma
4. Tumours
5. Vascular malformations

Question 14

Which orbital structure may give rise to a primary benign or malignant tumour?

Answer 14

Any orbital structure.
Primary tumours of most importance are: cavernous haemangioma; meningioma (especially of sphenoid bone or optic nerve sheath); benign and malignant tumours of the lacrimal gland; lymphoma.

Question 15

Name a bunch of other external and internal orbital tumours.

Answer 15

1. Secondary tumours (spread from adjacent or distant sites)
2. Dermoid cysts (upper nasal or temporal aspects of anterior orbit).
3. Capillary haemangioma (strawberry naevus on upper lid)
4. Optic nerve glioma (often in association with neurofibromatosis)
5. Rhabdomyosarcoma (may rarely mimic orbital cellulitis)

Local steroids may be necessary in capillary haemangiomas to prevent amblyopia, but usually regress spontaneously by school age.

Question 16

Name two vascular abnormalities which may lead to orbital eye disease.

Answer 16

1. Orbital varix (congenital venous abnormality which may not present until early adulthood. Proptosis is intermittent and related to posture and straining).
2. Carotico-cavernous fistula (communication between internal carotid artery and cavernous sinus. Affects elderly especially. Pulsatile proptosis associated with a loud bruit, haemorrhagic conjunctival swelling and dilated episcleral vessels).

Question 17

What is a pseudotumour?

Answer 17

Inflammation of the orbital soft tissues, at the orbital apex or in an extraocular muscle.
Pain is a common feature. Clinical features depend on location of focus: at orbital apex, get axial proptosis and optic nerve compression. With extraocular muscle involvement (orbital myositis), may cause proptosis and strabismus with double vision upon movement of the eye towards the affected muscle.