4.1 Visual system

Question 1

Name the defect caused by a localised defect in the retina (causing a small patch of visual loss)

Answer 1

Scotoma

Question 2

Name the pattern of visual loss caused by damage to an optic nerve

Answer 2

Left monocular blindness

Question 3

Name the pattern of visual loss caused by damage to an optic tract

Answer 3

Contralateral homonymous hemianopia

Question 4

Name the pattern of visual loss caused by damage to the lateral geniculate nucleus

Answer 4

Contralateral homonymous hemianopia

Question 5

Damage to both optic radiations leads to what pattern of visual loss

Answer 5

Contralateral homonymous hemianopia

Question 6

Non-vascular damage to the occipital lobe leads to what pattern of visual loss

Answer 6

Contralateral homonymous hemianopia WITHOUT macular sparing

Question 7

Occlusion of the Posterior Cerebral Artery leads to what pattern of vision loss

Answer 7

Contralateral homonymous hemianopia WITH macular sparing

Question 8

Name the blood supply to the macular region of the Occipital lobe

Answer 8

Middle cerebral artery

Question 9

Damage to the superior radiations causes which pattern of vision loss

Answer 9

Contralateral homonymous inferior quadrantanopia

Question 10

Damage to the inferior radiations causes which pattern of vision loss

Answer 10

Contralateral homonymous superior quadrantanopia (“Pie in the Sky” - Damage to Meyer’s Loop)

Question 11

Name the pattern of vision loss caused by occlusion to the central retinal artery

Answer 11

Amaurosis Fugax (curtain coming down over vision)

Question 12

Which method of imaging is used to visualise the layers of the retina

Answer 12

Optical coherence tomography (OCT)

Question 13

Examination of the retina by fundoscopy can detect which 3 diseases

Answer 13

Hypertensive retinopathy, diabetic retinopathy and macular degeneration

Question 14

What are the three layers of the eye?

Answer 14

1. Outermost sclera
2. Uvea (pigmented vascular layer)
3. Retina (neural layer)

Question 15

Name the layers of the Uvea

Answer 15

Choroid (sitting deep to sclera)

Ciliary body and Iris (sitting anteriorly)

Question 16

Name the layers of the Retina (superficial to deep)

Answer 16

(Superficial to deep in order)

1. Retinal pigment epithelium
2. Photoreceptor cells (Cones and Rods)
3. Bipolar cells (first order neurones). Horizontal cells here!
4. Ganglion cell layer (receive input from Bipolar cells)
5. Nerve fibre layer

Question 17

Bipolar cells receive input from…

Answer 17

Photoreceptor cells

Question 18

Bipolar cells are connected by…

Answer 18

Horizontal cells

Question 19

What is the role of Horizontal cells?

Answer 19

Horizontal cells connect bipolar cells and assist with ENHANCING EDGES through a process called LATERAL INHIBITION

Question 20

Name the processing centres in the Light Reflex

Answer 20

PRETECTAL NUCLEUS which projects bilaterally to the Edinger Westphal nuclei (which contain parasympathetic preganglionics)

Question 21

3 effects of the Accommodation Reflex

Answer 21

1. Pupillary Constriction
2. Convergence of the eyes (contraction of medial recti)
3. Thickening of the lens

Question 22

Name the processing centres in the Accommodation Reflex

Answer 22

Visual cortex (via the lateral geniculate nucleus), allowing processing of visual image which then project to oculomotor and edinger westphal nuclei

Question 23

Name the Fasiculus involved in the crossing over of (cranial/brainstem) nuclei which allows the eyes to move in a coordinated manner.

Answer 23

Medial Longitudinal Fasciculus

Question 24

Name a condition caused by a multiple sclerosis plaque in the medial longitudinal fasciculus

Answer 24

Internuclear Opthalmoplegia - reduced or slow adduction of the eye results (as the cortex prefers sending signals to the Abducens nerve than the Oculomotor nerve)