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Head, Neck and Neurology > The Eye > Flashcards

The Eye Flashcards

1
Q

Describe the position of the anterior chamber of the eye?

A

directly posterior to the cornea and anterior to the iris

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2
Q

What is the name of the central opening of the iris?

A

The pupil

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3
Q

What structure allows the posterior and anterior chamber of the eye to be continuous?

A

Pupillary opening

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4
Q

What substance fills the posterior and anterior chambers of the eye?

A

Aqueous humour

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5
Q

Where is aqueous humour absorbed?

A

Scleral venous sinus also called the canal of schlemm

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6
Q

What is the function of aqueous humour?

A

Supplies the avascular cornea and lens

maintains intraocular pressure

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7
Q

What gelatinous substance fills the eye from the lens to the retina?

A

Vitreous humour

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8
Q

Describe the layered structure of the walls of the eyeball.

A

Outermost fibrous layer - sclera posteriorly and cornea anteriorly
middle vascular layer - choroid posteriorly and ciliary body and iris anteriorly
the innermost layer - optic part of retina posteriorly, non visual retina anteriorly

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9
Q

The cornea is transparent. t/f?

A

true

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10
Q

What is the name of the highly vascular, pigmented layer of the wall of the eyeball?

A

Choroid

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11
Q

Parasympathetic fibres from which nerve innervate the ciliary muscles?

A

Occulomotor (CN III)

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12
Q

What is the name of the fibres which form the suspensory ligament of the lens?

A

Zonular fibres

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13
Q

How does contraction of the ciliary body affect the lens of the eye?

A

Contraction of the ciliary muscle decreases the size of the ring formed by the ciliary body which reduces tension on the suspensory ligament of the lens and allows the lens to become more rounded to accommodate near vision

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14
Q

Parasympathetic fibres innervate which muscle in the iris to constrict the pupil?

A

Sphincter pupillae muscle

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15
Q

Sympathetic fibres innervate which muscle in the iris to dilate the pupil?

A

dilator pupillae muscle

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16
Q

What is the name of the point at which the optic nerve leaves the retina?

A

Optic disc

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17
Q

The optic disc is a blind spot of the retina. T/F?

A

True

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18
Q

What is the name of the thinnest area of the retina which is most visually sensitive?

A

Five centralis

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19
Q

Which vessels provide blood supply to the eye?

A

Short posterior ciliary arteries
Long posterior ciliary arteries
Anterior ciliary arteries
Retinal artery

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20
Q

Which artery of the eye enters the area of the retina at the optic disc?

A

Central retinal artery

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21
Q

The short posterior ciliary artery is a branch of which artery?

A

Ophthalmic artery

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22
Q

The vortices veins drain the eyeball and enter the superior and inferior ophthalmic veins. There is also an additional vein draining the eyeball called the…?

A

Central retinal vein

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23
Q

Photoreceptors in the eye are located next to the retinal pigment epithelium. T/F?

A

True

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24
Q

What type of photoreceptor exists within the fovea centralis?

A

Cone cells

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25
Q

Signals from a number of photoreceptors can converge onto a single bipolar cell. T/F?

A

True

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26
Q

An aldehyde of which vitamin (11-cis-retinal) alongside a protein called opsin make up rhodopsin which is the pigment contained within rod cells?

A

Vitamin A

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27
Q

Which type of photoreceptor have 11-cis-retinal conjugated to different photoreceptor proteins to make different type fo that photoreceptor cell sensitive to different wavelengths of light?

A

Cone cells

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28
Q

Which type of photoreceptor can function well even in dark conditions?

A

Rod cells

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29
Q

Photoreceptors are relatively depolarised at rest and become hyper polarised in response to an adequate stimulus. T/F?

A

True - this is what makes them unique

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30
Q

When a photon of light is captured by the visual pigment molecules in a photoreceptor 11-cis-retinal changes to 11-trans retinal and dissociates from opsin to which it is normally bound. This activates a G protein called…?

A

Transducin

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31
Q

How does the activation of a photoreceptor by light affect cGMP to cause hyper polarisation?

A

It decreases the levels of cGMP so that fewer sodium ion channels are open and hyper polarisation occurs

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32
Q

When photoreceptors are depolarised they release a neurotransmitter onto bipolar cells, this neurotransmitter release is decreased when light activates the photoreceptors to cause hyperpolarisation. What neurotransmitter is used?

A

Glutamate

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33
Q

In the absence of light, ganglion cells in the ON-pathway are not stimulated to fire an action potential. Explain how this happens

A

When there is no light, glutamate is released onto ON-bipolar cells, causing hyper polarisation of the bipolar cells which prevents the release of excitatory neurotransmitter onto associated ganglion cells.

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34
Q

In the absence of light, ganglion cells in the OFF-pathway are stimulated to fire an action potential. Explain how this happens

A

When there is no light, glutamate is released onto OFF-bipolar cells, causing depolarisation of the bipolar cells which results in the release of excitatory neurotransmitter onto associated ganglion cells

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35
Q

What is the name of the point at which partial decussation of the optic nerve occurs?

A

Optic chiasm

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36
Q

What is the name of the fibre tract which exists beyond the point of the optic chiasm?

A

Optic tract

37
Q

From the optic tract, to which structures of the brain to fibres pass?

A

Lateral geniculate bodies of the thalamus
Superior colliculi
Oculomotor nuclei

38
Q

Fibres pass from the lateral geniculate bodies of the thalamus to the primary visual cortex in the occipital lobe. What is the name of this fibre tract?

A

Optic radiations

39
Q

What is the name for the type of vision which provides clues about the distance of objects?

A

Stereoscopic vision

40
Q

Dry AMD can progress to Wet AMD. T/F?

A

True

41
Q

What are the risk factors for age related macular degeneration?

A 
Age
Family history
current smoker
previous cataract surgery
cardiovascular disease
high BMI
Hypertension
Low dietary intake of vitamins A,C and E, omega-3 fatty acids, lutein and zinc
42
Q

Which genes predispose age related macular degeneration?

A

Complement factor h

43
Q

Describe the pathophysiology of Dry AMD?

A

Deposition of extracellular material along the inner aspect fo Bruch’s membrane (which separates RPE from choroid) alters the permeability of Bruch’s membrane resulting in decreased nutrient delivery to RPE cells and secondary metabolic stress. This leads to RPE cellular damage and secondary loss of adjacent photoreceptors and choriocapillaris

44
Q

Describe the pathophysiology of Wet AMD?

A

Ischaemia of the RPE may lead to increased production of VEGF which stimulates neovascularisation of the choriocapillaris. choroidal neovascular vessels break through Bruch’s membrane and are prone to Leakage, leading to sub retinal and itnraretinal fluid accumulation

45
Q

What is Bruch’s membrane?

A

A membrane which separates the retinal pigment epithelium from the choroid

46
Q

What are Drusen?

A

Tiny yellow or white accumulations of extracellular material that build up between Bruch’s membrane and the RPE

47
Q

It is normal for there to be a fews all Drusen present with advancing age. T/F?

A

True

48
Q

Drusen are composed of apolipoproteins and oxidised proteins which likely arise from which tissues/structures?

A

Blood
RPE
Photoreceptors

49
Q

What are the signs on fundus examination of Wet AMD?

A 
Subretinal haemorrhage
pigment epithelium detachment
retinal thickening
oedema
lipid exudates
50
Q

Medium sized Drusen are seen in the early stages of AMD. T/F?

A

True

51
Q

AMD is often bilateral. T/F?

A

True

52
Q

Optic coherence tomography is a non-invasive test used to confirm whether sub retinal or intraretinal fluid is present in AMD. It can also be used for?

A

Determining volume fo fluid present before initiating treatment
Monitoring changes in volume of fluid in response to treatment

53
Q

Other than optical coherence tomography what other test is used in the detection of choroidal neovascularisation?

A

Fluorescein angiography

54
Q

Patients with early AMD have few or no visual symptoms. T/F?

A

True

55
Q

There is severe vision loss in Late AMD. T/F?

A

True

56
Q

What is the treatment for early AMD?

A

Risk factor modification: smoking cessation, dietary modification and atherosclerotic risk factor modification
antioxidant/mineral supplementation

57
Q

VEGF inhibitors are used in the treatment of Wet AMD.. Give examples of these drugs?

A

Ranibizumab
Bevacizumab
Aflibercept

58
Q

What are the pros and cons of using ranibizumab rather than bevacizumab (both VEGF inhibitors) in the treatment of Wet AMD?

A

Ranibizumab is licences whereas benvacizumab is not

Bevacizumab is cost effective whereas ranibizumab is not

59
Q

Other than VEGF inhibitors, what are the potential treatments for Wet AMD?

A

Photodynamic therapy with verteporfin

thermal laser photocoagulation

60
Q

What is the macula of the eye?

A

Oval shaped pigmented area near the centre of the retina

61
Q

Which area of the eye is responsible for detailed vision such as used in reading, facial recognition and visual acuity?

A

Macula

62
Q

There are no blood vessels in the macula. T/F?

A

True - it is dependent on the choroid for metabolic support

63
Q

If on a visual acuity test a patient has 6/36 vision what does this mean?

A

The patient can read at 6m what should be read at 36m

64
Q

What level of vision is required for driving?

A

6/12

65
Q

If a person wears corrective lenses for distance, then they should not wear their glasses during a visual acuity test. T/F?

A

False - they should wear their glasses

66
Q

In a fungus fluorescein angiogram, fluorescein bound to which substance is injected interocularly?

A

Albumin

67
Q

A blue flash and then what colour filter is used in fungus fluorescein angiograms to see the details of the retinal circulation?

A

Yellow filter

68
Q

Doppler techniques can be used in optical coherence tomography and this is being used as a non-invasive alternative to…?

A

Fungus fluorescein angiograms

69
Q

In what areas in the world is blindness most common?

A

South east Asia
africa
west pacific

70
Q

What are the major causes of blindness worldwide?

A

Glaucoma, cataracts, ARMD, corneal scars, diabetic retinopathy, childhood blindness, trachoma

71
Q

What are the major causes of blindness in Scotland?

A

AMD, glaucoma, diabetic retinopathy, myopic degeneration and optic atrophy

72
Q

In which hemisphere of the occipital lobe are signals from the left visual field processed?

A

Right primary visual cortex in occipital lobe

73
Q

Some fibres continue on the same side in the optic tract as in the optic nerve but some fibres decussate at the optic chiasm. Fibres from which side of the retina decussate at the optic chiasm?

A

Nasal side

74
Q

Partial of complete loss of vision in the ipsilateral eye will result from lesions of the optic nerve. What might cause these lesions?

A

Acute optic neuritis (multiple sclerosis)
indirect traumatic optic neuropathy
optic atrophy

75
Q

Lesions of the optic chiasm will cause loss of vision in which visual field?

A

Temporal visual fields

76
Q

Lesions of the optic chiasm cause bitemporal hemianopia. What might cause this?

A

Tumours (pituitary adenoma or meningioma), or aneurysms

77
Q

Lesions of the optic tract cause homonymous hemianopia. What may cause this?

A

Tumours, trauma or aneurysm of posterior cerebral artery

78
Q

Homonymous hemianopia can be caused by lesions at what points in the visual pathway?

A

Lesions of the optic tract, lateral geniculate nucleus, optic radiation or visual cortex

79
Q

Not all fibres from the optic nerve pass to the lateral geniculate nuclei. Some pass to the superior colliculus and to the pretectal area of the midbrain. What are the roles of the superior colliculus and pretectal area of midbrain?

A

Superior colliculus controls eye movements

Pretectal area is responsible for the pupillary light reflex

80
Q

What aspect of vision do goldmann perimetry tests assess?

A

Visual fields

81
Q

What is the accommodation reflex?

A

Pupil constriction and convergence of the eyes when looking from a distant object to a close one

82
Q

What nerves are involved in the afferent and efferent pathways of the pupillary light reflex and accommodation reflex?

A

Afferent - optic nerve

Efferent - oculomotor nerve

83
Q

When light is shone on one eye only, there is consensual constriction of the contralateral pupil also. T/F?

A

True

84
Q

What is the name of the nuclei in the pupillary light reflex which generates action potentials through the oculomotor nerve to cause pupil constriction?

A

Edinger-Westphal nuclei

85
Q

In what region of the midbrain do the Edinger-Westphal nuclei (involved in the pupillary light reflex) exist?

A

Pretectal nuclei

86
Q

A small difference of size of approx 1-2mm in the pupils may be normal. T/F?

A

True

87
Q

What is the test for relative afferent pupil defects?

A

Swinging light test

88
Q

The swinging light test can identify asymmetry of afferent input in the pupillary light reflex. What defect does this indicate?

A

Relative afferent pupil defects (RAPD)

Head, Neck and Neurology (24 decks)

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