Eye

Question 1

Myopia

Answer 1

• Short sighted
• Light focuses at a point before the retina
• Connected with concave lens
• Larger eye

Question 2

Hypermetropia

Answer 2

• Long sighted
• Light focuses at a point beyond the retina
• Smaller eye
• Corrected with a convex lens

Question 3

Describe the properties of rods

Answer 3

• 120 million in the retina
• High convergence to ganglion cells
• Very light sensitive
• Widespread in the retina
• Broad spectral sensitivity
• One type - vision in greyscale

Question 4

Describe the properties of cones

Answer 4

• 6 million in the retina
• Low convergence to ganglion cells
• 3 types: blue, red, green
• 1/30th sensitivity of rods
• concentrated in the macula
• narrow spectral sensitivity

Question 5

Lesion of right optic nerve

Answer 5

Right eye vision loss

Question 6

Lesion of the optic chiasm

Answer 6

Bitemporal hemianopia

Question 7

Lesion of right lateral geniculate nucleus

Answer 7

Left hemianopia

Question 8

Lesion of the parietal lobe

Answer 8

Inferior quadrantinopia

Question 9

Lesion to the temporal lobe

Answer 9

superior quadrantinopia

Question 10

Lesion of the right primary visual cortex

Answer 10

Left hemianopia

Question 11

What is Meyer’s loop?

Answer 11

• Inferior optic radiation that goes through the temporal lobe
• Information from the upper part of the visual field

Question 12

What are the two streams of vision?

Answer 12

• Dorsal stream: ‘where’ , parietal lobe, allows us to see one thing among many
• Ventral stream: ‘what’, temporal lobe, helps us to recognise objects/faces etc.

Question 13

What is the role of the occipital lobe in vision

Answer 13

Primary vision cortex

Question 14

What is the role of the temporal lobe in vision?

Answer 14

• Ventral stream (What pathway)

* Hosts our visual library

Question 15

What is the role of the parietal lobe in vision?

Answer 15

• Dorsal stream

* Serves function of attention

Question 16

What is the role of the frontal lobe in vision?

Answer 16

• Execution of a plan

Question 17

Peri-ventricular leucomalacia

Answer 17

• Holes in the Brian caused by death of cells around the ventricles
• Ischaemic damage

Question 18

What is simultanagnosia?

Answer 18

• Difficulty finding one thing amongst many

* Bilateral parietal brain damage from cerebrovascular accident

Question 19

What is achromatopsia?

Answer 19

• Unable to see colour - everything is grey

* Bilateral anterior occipital brain damage

Question 20

What is visual acuity

Answer 20

the ability of the visual system to resolve a gap between two objects- spatial resolution

Question 21

How can you test visual acuity?

Answer 21

• Snellen chart
• 6 metre distance
• Cover one eye, read then switch eyes
• Result recorded as 6/x

Question 22

What is driving vision

Answer 22

• Better than or equal to 6/12

Question 23

Pupil pathway

Answer 23

• Light -> retina
• Optic nerve
Efferent: Oculomotor

Question 24

What is RAPD

Answer 24

• Relative afferent pupillary defect
• Pupils respond different to stimuli shone in one eye at a time due to unilateral or asymmetrical disease of retina or optic nerve

Question 25

What are the causes of RAPD?

Answer 25

``` Unilateral or assymetrical disease of the retina or optic nerve: • Optic neuritis • Anterior ischaemic optic neuropathy • Trauma, pressing on the optic nerve • Glaucoma - most common ```

Question 26

What can cause the appearance of a swollen disc?

Answer 26

``` • Pseudo swelling: - small disc - calcium deposits 'drusen' • Genuine swelling: - optic neuritis (VA reduced: associated with MS) - Idiopathic intracranial hypertension - hydrocephalus ```

Question 27

Nerve supply to the eye muscles

Answer 27

* Most = oculomotor * Superior oblique: glossopharyngeal * Lateral rectus = accessory

Question 28

3rd Cranial nerve palsy

Answer 28

* Vertical diplopia * Eye down and out * Dilated pupil and ptosis * Can be associated with aneurysm - needs urgent brain scanning and angiogram

Question 29

4th cranial nerve palsy

Answer 29

* Oblique diplopia * Head tilt away from the side of the lesion * Diplopia worse away from the side of the palsy if unilateral * Common after a head injury * If bilateral, may be congenital

Question 30

6th Cranial nerve palsy

Answer 30

* Horizontal diplopia * Worse in far distance * Worse towards side of palsy if unilateral * If bilateral, concerned about raised ICP

Question 31

Which cranial nerve palsy is a medical emergency?

Answer 31

3rd Cranial nerve - oculomotor | • Associated with aneurysm