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MD4001 > Eye > Flashcards

Eye Flashcards

1
Q

Myopia

A
  • Short sighted
  • Light focuses at a point before the retina
  • Connected with concave lens
  • Larger eye
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2
Q

Hypermetropia

A
  • Long sighted
  • Light focuses at a point beyond the retina
  • Smaller eye
  • Corrected with a convex lens
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3
Q

Describe the properties of rods

A
  • 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
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4
Q

Describe the properties of cones

A
  • 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
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5
Q

Lesion of right optic nerve

A

Right eye vision loss

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6
Q

Lesion of the optic chiasm

A

Bitemporal hemianopia

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7
Q

Lesion of right lateral geniculate nucleus

A

Left hemianopia

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8
Q

Lesion of the parietal lobe

A

Inferior quadrantinopia

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9
Q

Lesion to the temporal lobe

A

superior quadrantinopia

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10
Q

Lesion of the right primary visual cortex

A

Left hemianopia

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11
Q

What is Meyer’s loop?

A
  • Inferior optic radiation that goes through the temporal lobe
  • Information from the upper part of the visual field
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12
Q

What are the two streams of vision?

A
  • 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.
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13
Q

What is the role of the occipital lobe in vision

A

Primary vision cortex

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14
Q

What is the role of the temporal lobe in vision?

A
  • Ventral stream (What pathway)

* Hosts our visual library

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15
Q

What is the role of the parietal lobe in vision?

A
  • Dorsal stream

* Serves function of attention

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16
Q

What is the role of the frontal lobe in vision?

A

• Execution of a plan

17
Q

Peri-ventricular leucomalacia

A
  • Holes in the Brian caused by death of cells around the ventricles
  • Ischaemic damage
18
Q

What is simultanagnosia?

A
  • Difficulty finding one thing amongst many

* Bilateral parietal brain damage from cerebrovascular accident

19
Q

What is achromatopsia?

A
  • Unable to see colour - everything is grey

* Bilateral anterior occipital brain damage

20
Q

What is visual acuity

A

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

21
Q

How can you test visual acuity?

A
  • Snellen chart
  • 6 metre distance
  • Cover one eye, read then switch eyes
  • Result recorded as 6/x
22
Q

What is driving vision

A

• Better than or equal to 6/12

23
Q

Pupil pathway

A

• Light -> retina
• Optic nerve
Efferent: Oculomotor

24
Q

What is RAPD

A
  • 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
25
Q

What are the causes of RAPD?

A 
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
26
Q

What can cause the appearance of a swollen disc?

A 
• Pseudo swelling: 
- small disc 
- calcium deposits 'drusen'
• Genuine swelling:
- optic neuritis (VA reduced: associated with MS) 
- Idiopathic intracranial hypertension 
- hydrocephalus
27
Q

Nerve supply to the eye muscles

A
  • Most = oculomotor
  • Superior oblique: glossopharyngeal
  • Lateral rectus = accessory
28
Q

3rd Cranial nerve palsy

A
  • Vertical diplopia
  • Eye down and out
  • Dilated pupil and ptosis
  • Can be associated with aneurysm - needs urgent brain scanning and angiogram
29
Q

4th cranial nerve palsy

A
  • 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
30
Q

6th Cranial nerve palsy

A
  • Horizontal diplopia
  • Worse in far distance
  • Worse towards side of palsy if unilateral
  • If bilateral, concerned about raised ICP
31
Q

Which cranial nerve palsy is a medical emergency?

A

3rd Cranial nerve - oculomotor

• Associated with aneurysm

MD4001 (28 decks)

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