Session 9: Group Work

Question 1

Which bones and therefore walls of the orbit are the weakest and therefore most vulnerable to fracture in orbital trauma?

Answer 1

Floor (maxilla)

Medial wall (ethmoid bone)

Question 2

Why are the bones that you listed most easily fractured?

Answer 2

Because they are thin

Question 3

What structure of the lacrimal appartus is found within the lacrimal fossa and where does it drain into?

Answer 3

Lacrimal sac

Drains into the nasolacrimal duct

Question 4

What structures pass through the optic canal?

Answer 4

Optic nerve and ophthalmic artery

Question 5

What structures passes through the superior orbital fissure?

Answer 5

CN Va

Trochlear nerve

Oculumotor nerve

Abducens nerve

Superior ophthalmic vein

Question 6

Name two conditions that can affect the lens.

Answer 6

Cataracts

Presbyopia

Question 7

Label the retinal artery, retinal vein, optic disc and macula.

Answer 7

Question 8

Is this a view of the right or left retina?

How do you know?

Answer 8

Right retina

Because the macula is supposed to be found lateral to the optic disc

Question 9

From which artery have the arterial vessels visible on the retina arisen?

How did this artery get into the back of the eye?

Answer 9

Ophthalmic arery via the optic canal.

Question 10

A man attends the emergency department with a irritable, watery and red right eye. What is the diagnosis and why is the cornea not affected?

Answer 10

Conjunctivitis

The conjunctivae is not found on the cornea. It ends at the limbus.

Question 11

During his eye examination the doctor tests the man’s distance visual acuity using a Snellen Chart.

His VA is recorded as 6/9 in his right eye and 6/12 in his left eye.

What does 6/9 and 6/12 mean, in which eye is VA better?

Answer 11

6 meters

Row 9 or row 12 (stands for size of the letters)

6/9 is a better VA

Question 12

The man normally wears glasses but does not have them with him. The test is repeated using a pinhole and the acuity in both eyes improves.

What does this tell you about the likely cause for his reduced VA?

Explain your reasoning.

Answer 12

That the problem is a refractory problem.

During pinhole testing the light is focused on one point and doesn’t need to be refracted into the retina to focus.

This gives a clearer image if your visual problems are due to refractory problems.

Question 13

Explain briefly clinical examination of the eye.

Answer 13

IVA FROM

I - inspection (general)

VA - Visual acuity

F - Visual fields

R - Light and accommodation reflexes

O - Ophthalmoscope

M - Motor function