Visual System

Question 1

How does sensory information from the eye travel to the Primary visual cortex? What is its route

Answer 1

Eye -> Optic nerve -> Optic chiasm -> Optic tract -> Lateral geniculate nucleus -> Optic radiation -> Primary visual cortex

Question 2

Where is the primary visual cortex located? What Broadmann’s area is it?

Answer 2

Occipital lobe, Brodmann’s area 17, 18, 19

Question 3

If a patient experiences a visual field loss which is homonymous (same side in both eyes), what does this suggest?

Answer 3

The lesion has occured posterior to the optic chiasm

Question 4

Lesions occuring at the optic chiasm would lead to what type of partial blindness?

Answer 4

Heteronymous hemianopia (loss of vision in opposite fields of each eye)

Question 5

Complete blindness in one visual field (left or right) would suggest a lesion were?

Answer 5

Optic nerve

Question 6

What are the three main layers of the eye?

Answer 6

• Fibrous later (outermost)
• Vascular layer (middle)
• Neural layer (inner)

Question 7

What two structures comprise the Fibrous layer (outer layer) of the eye?

Answer 7

Cornea and sclera

Question 8

What three structures comprise the Vascular layer (middle layer) of the eye?

Answer 8

Iris, cilliary body and choroid

Question 9

What one structure comprises the Neural layer (inner layer) of the eye?

Answer 9

Retina

Question 10

What is the centre part of the retina called?

Answer 10

Fovea (highest resolution of vision, highest density of neurones)

Question 11

What are the two main functions of eye movements?

Answer 11

Gaze stabilisation

Gaze shifting

Question 12

Which muscle closes the eyelid?

Answer 12

Levator Palpebrae Superioris (LPS)

Question 13

What are the 6 extrinsic muscles of the eye

Answer 13

Superior Oblique
Inferior Oblique
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus

Question 14

What is the main function of the Medial Rectus muscle?

Answer 14

Adduction of eye

Question 15

What is the main function of the Lateral Rectus muscle?

Answer 15

Abduction of eye

Question 16

What is the main function of the Inferior Rectus muscle?

Answer 16

Depression of eye

Question 17

What is the main function of the Superior Rectus muscle?

Answer 17

Elevation of eye

Question 18

What is the main function of the Superior Oblique muscle?

Answer 18

Intorsion of eye

Question 19

What is the main function of the Inferior Oblique muscle?

Answer 19

Extortion of eye

Question 20

Cranial Nerve III (Oculomotor) innervates what Extrinsic eye muscles?

Answer 20

Medial Rectus
Inferior Rectus
Superior Rectus
Inferior Oblique

Question 21

Cranial Nerve IV (Trochlear) innervates what Extrinstic eye muscle?

Answer 21

Superior Oblique (SO4)

Question 22

Cranial Nerve VI (Abducens) innervates what Extrinstic eye muscle?

Answer 22

Lateral Rectus (LR6)

Question 23

Which part of the brain controls eye movements?

Answer 23

Frontal Eye Field (FEF)

Question 24

Which part of the brain controls planning of eye movements?

Answer 24

Supplementary Eye Field (SEF)

Question 25

Which part of the brain is involved in maintaining visual attention?

Answer 25

Posterior Parietal Cortex

Question 26

What is the role of Supplementary Eye Field (SEF)?

Answer 26

Planning of eye movements

Question 27

What is the role of Posterior Parietal Cortex?

Answer 27

Maintaining visual attention

Question 28

What is the role of Superior Colliculus with respect to eyes?

Answer 28

Orientation to object in the visual field

Question 29

What is Anisocoria?

Answer 29

Unequal size of pupils in eyes

Question 30

Pupil constriction is also known as..? Is the iris sphincter active or relaxed?

Answer 30

Miosis, sphincter active

Question 31

Pupil dilation is also known as..? Is the iris sphincter active or relaxed?

Answer 31

Mydriasis, sphincter relaxed

Question 32

Miosis and Mydriasis is under sympathetic or parasympathic control?

Answer 32

``` Miosis = Parasympathetic Mydriasis = Sympathetic ```

Question 33

The accomodation reflex is under what control? Sympathetic or parasympthatic?

Answer 33

Parasympathetic control

Question 34

What are Cataracts?

Answer 34

Clouding of lens caused by compaction and protein deposition

Question 35

What are risk factors for Cataracts?

Answer 35

Aging, trauma, diabetes, smoking, UVB light, genetic (congenital cataracts)

Question 36

What is the anterior chamber filled with?

Answer 36

Aqueous humour

Question 37

What is the role of Cilliary epithelium of the Ciliary body in the eye?

Answer 37

Production of Aqueous humour for the Anterior and Posterior Chamber

Question 38

How is the Aqueous humour drained from the eye?

Answer 38

Out of the lens, through pupil, into anterior chamber. The drain through trabecular meshwork and then Schlemm's canal and out of the eye

Question 39

What are risk factors for Glaucoma's?

Answer 39

Raised intraocular pressure (normal = 12-22) Hypertension Long-term steroid use Severe myopia (-6.00)

Question 40

What is the most common type of Glaucoma? What is it caused by? Is it acute or chronic?

Answer 40

Open-angle Glaucoma, caused by blockage of Trabecular meshwork. It is chronic

Question 41

What is closed-angle Glaucoma caused by?

Answer 41

Caused by raised intra-ocular pressure which bows the iris and closes the anterior chamber. It is an acute medical emergency

Question 42

What are some treatment options for Glaucoma? 4 groups

Answer 42

- Beta blockers - Alpha2 adrenoceptor agonists - Carbonic anhydrase inhibitors - Miotics (muscarinic agonists)

Question 43

What is the mechanism of action for Acetazolamide?

Answer 43

Carbonic anhydrase inhibitor, preventing Sodium reabsorption and thus allowing water secretion and reduction of Intraocular pressure

Question 44

What is the main blood supply to the eye?

Answer 44

Choroid and choriocapillaries (outer retina) | Central retinal artery and vein (inner retina)

Question 45

Is the fovea vascular or avascular?

Answer 45

Avascular

Question 46

Red/green colour blindness particularly affects which gender? Why?

Answer 46

Red-green colour blindness, because it is X-linked

Question 47

What are the two cell types in the Lateral genicular nucleus? What do they detect?

Answer 47

Magnocellular (detects light / dark) | Parvocellular (detects colour)