9 - Head & Neck - The Eye

Question 1

Which bones form the orbit?

Answer 1

• Sphenoid bone
• Ethmoid bone
• Frontal bone
• Lacrimal bone
• Maxillary bone
• Zygomatic bone

Question 2

List the boundaries of the orbit:

Answer 2

Apex = Optic canal
Roof = Frontal + Sphenoid
Floor = Maxillary + Zygomatic
Lateral = Zygomatic + Sphenoid
Medial = Lacrimal + Ethmoid + Maxillary + Sphenoid

Question 3

Which wall of the orbit is the weakest?

Answer 3

Base of orbit

Question 4

Name the tissue of the eye to which the extra-ocular muscles attach to:

Answer 4

Sclera

Question 5

Why does the eye appear red if patient has conjunctivitis? Why does conjunctivitis not affect the iris or pupil?

Answer 5

• Blood vessels in the conjunctivae dilate due to inflammation
• Conjunctivae covers sclera up to the cornea (does not cover pupil/iris)

Question 6

Which structures of the eye are avascular? How do they recieve nutrients?

Answer 6

• Lens
• Cornea

via Aqueous humour

Question 7

Name the tissues which form the outer tough layer of the eyeball:

Answer 7

• Sclera

- Conjunctiva

Question 8

Name the tissues which form the middle layer of the eyeball:

Answer 8

• Choroid
• Ciliary body
• Iris

Question 9

Which structure makes up the inner layer of the eyeball?

Answer 9

Retina

Question 10

Which layer of the eyeball contains a rich network of blood vessels?

Answer 10

Middle layer (mainly in choroid)

Question 11

Name the 3 chambers of the eyeball, and the fluid which fills each:

Answer 11

1) Anterior chamber - Aqueous humour
2) Posterior chamber - Aqueous humour
3) Vitreous chamber - Vitreous humour

Question 12

How does the anterior chamber of the eye communicate with the posterior chamber?

Answer 12

Through the pupil

Question 13

Which structures of the eye secrete aqueous humour?

Answer 13

• Ciliary body

- Ciliary processes

Question 14

What are the roles of the ciliary body?

Answer 14

• Controls thickness and focus of lens
• Varies opening of trabeculae meshwork
• Secretes aqueous humour

Question 15

Describe the drainage of aqueous humour into the venous system:

Answer 15

• Through Irido-corneal angle

- Into canal of Schlemm via trabecular meshwork

Question 16

Name the 3 canals which open into the orbit, and which bone they lie in:

Answer 16

• Superior orbital fissure
• Inferior orbital fissure
• Optic canal

= Sphenoid bone

Question 17

Which structures run in the optic canal?

Answer 17

• Optic nerve

- Ophthalmic artery

Question 18

Which structures run in the superior orbital fissure?

Answer 18

• Oculomotor nerve (sup. + inf. branches)
• Trochlear nerve
• Abducens nerve
• Ophthalmic nerve (frontal, lacrimal + nasociliary branches)
• Superior ophthalmic vein

Question 19

Which structure runs in the inferior orbital fissure?

Answer 19

• Inferior ophthalmic vein

Question 20

What is a ‘blow-out fracture’?

Answer 20

Fracture of orbit, usually medial wall + floor

Question 21

What is Reiter’s syndrome?

Answer 21

Conjunctivitis, arthritis + urethritis

- Autoimmune reactive arthritis due to bacterial infection

Question 22

What is the classical presentation of an Oculomotor nerve lesion?

Answer 22

• Ptosis
• Fully dilated pupil
• ‘Down-and-out’ eye

Question 23

Why may someone with a facial nerve palsy have to consistently dab eye due to constant weeping?

Answer 23

Paralysis of orbicularis oculi
= Inferior eyelid pulls away, exposing cornea
= Constant irritation
= Increased lacrimal secretion

Question 24

What is cataracts? Who does it commonly affect?

Answer 24

Opacification of the lens
= reduced vision
= reduced acuity
= reduced contrast sensitivity

Diabetics, smokers, elderly

Question 25

What is Presbyopia?

Answer 25

The natural long-sightedness occurring with age, due to loss of elasticity of lens

Question 26

How does retinal detachment present? What causes these symptoms?

Answer 26

Blurring of vision, black dots/streaks, sudden flashes of light

Retina detaches from choroid (which contains blood supply), leading to avascular necrosis of retina.

Question 27

Name the most common type of glaucoma:

Answer 27

Open-angle glaucoma

Question 28

What is open-angle glaucoma?

Answer 28

Increased intra-ocular pressure due to blockage within trabecular meshwork of eye = damaged optic nerve
Develops slowly and painlessly.
Signs = optic disc cupping, loss of visual field

Question 29

What is the treatment for open-angle glaucoma?

Answer 29

• Eyedrops to reduce aqueous humour production: beta-blockers ie Timolol
• Surgery (trabeculectomy)

Question 30

What is closed-angle glaucoma?

Answer 30

Rapid increase in intracranial pressure due to narrowing of irido-corneal angle