Eye Flashcards

1
Q

What forms the roof of the orbit?

A

Frontal bone

Lesser wing of sphenoid

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2
Q

What forms the floor of the orbit?

A

Maxillary bone
Palatine bone
Zygomatic bone

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3
Q

What forms the medial wall of the orbit?

A

Lacrimal bone
Ethmoid bone
Maxillary bone
Sphenoid bone

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4
Q

What forms the lateral wall of the orbit?

A

Zygomatic bone

Greater wing of sphenoid

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5
Q

What forms the apex of the orbit?

A

Optic canal

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6
Q

What are the openings into the orbit?

A

Optic canal
Superior orbital fissure
Inferior orbital fissure

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7
Q

What is the arterial supply to the orbit?

A

Ophthalmic artery

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8
Q

What is the venous drainage of the orbit?

A

Superior ophthalmic vein

Inferior ophthalmic vein

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9
Q

Where does the superior ophthalmic vein drain?

A

Cavernous sinus

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10
Q

Where does the inferior ophthalmic vein drain?

A

Pterygoid plexus

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11
Q

What provides general sensory innervation to eye?

A

CN Va

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12
Q

What are the weakest parts of the orbit?

A

Medial wall + floor

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13
Q

What is an orbital blowout fracture?

A

Traumatic fracture of medial wall or floor of orbit

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14
Q

What causes an orbital blowout fracture?

A

Sudden increase in intra-orbital pressure often due to fist or ball hitting eye

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15
Q

What happens in an orbital blowout fracture?

A

Orbital contents can prolapse and bleed into maxillary sinus

Fracture site can ‘trap’ structures

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16
Q

What are the signs of an orbital blowout fracture?

A
Loss of upward gaze on affected size
History of trauma 
Periorbital swelling 
Double vision 
Anaesthesia over affected cheek
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17
Q

What causes anaesthesia in an orbital blowout fracture?

A

Infraorbital branch of CNVb runs through floor of orbit

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18
Q

What makes up the eyelids?

A
Skin
Subcutaneous tissue 
Tarsal plate
Orbicularis oculi 
Levator palpaebrae superioris 
Meibomian glands
Sebaceous glands - associated with eyelash follicles
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19
Q

What do Meibomian glands secrete?

A

Meibum - an oily substance that prevents the evaporation of the tear film

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20
Q

What do sebaceous glands secrete?

A

Sweat

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21
Q

What is caused by a blockage of a Meibomian gland?

A

Meibomian cyst

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22
Q

What is a stye?

A

Infection due to blockage of sebaceous gland or eyelash follicle

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23
Q

Where do Meibomian glands lie?

A

Within the tarsal plate

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24
Q

What is the orbital septum?

A

Thin sheet of fibrous tissue that originates from the orbital rim periosteum and blends with the tarsal plates

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25
Q

What is the role of the orbital septum?

A

Prevents superficial infection spreading into orbit

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26
Q

What is peri-orbital cellulitis?

A

Infection occurring within eyelid tissue - superficial to orbital septum

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27
Q

Where does peri-orbital cellulitis effect?

A

Confined to tissues superficial to orbital septum

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28
Q

What happens to ocular function in peri-orbital cellulitis?

A

Unaffected

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29
Q

What is orbital cellulitis?

A

Infection within the orbit - deep to orbital septum

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30
Q

What are the signs of orbital cellulitis?

A

Proptosis
Exophthalmos
Reduced/painful eye movements
Reduced visual acuity

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31
Q

What is the risk of orbital cellulitis?

A

Can spread intracranially - via venous system

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32
Q

What is proptosis?

A

Protrusion of the eyeball

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33
Q

What is exophthalmos?

A

Appearance of protruding eyes

34
Q

What are the contents of the orbital cavity?

A
Eyeball 
Fat
Extra-ocular muscles 
Nerves
Blood vessels
Lacrimal apparatus
35
Q

What is the lacrimal apparatus?

A

Structures involved in tear film production and drainage

36
Q

What makes up the lacrimal apparatus?

A

Lacrimal gland
Lacrimal sac
Lacrimal ducts

37
Q

What produces tears?

A

Lacrimal gland

38
Q

What drains tears?

A

Lacrimal ducts

  • canaliculi
  • nasolacrimal duct
39
Q

What happens with tears?

A

Blinking washes tear film across front of eye

Drain into nasal cavity

40
Q

What is epiphora?

A

Overflow of tears over lower eyelid

41
Q

What is the role of tears?

A

Lubricate conjunctiva and cornea

42
Q

How many layers does the eyeball have?

A

3

43
Q

What are 3 layers?

A

Outer
Middle
Inner

44
Q

What forms the outer layer?

A

Sclera

Cornea

45
Q

What forms the middle layer?

A

Choroid
Ciliary body
Iris

46
Q

What forms the inner layer?

A

Retina

47
Q

What is the retina?

A

Inner photosensitive layer lying on an outer pigmented layer

48
Q

What is the conjunctiva?

A

Transparent mucous membrane producing mucous and tears

49
Q

Where does the conjunctiva lie?

A

Covers sclera, lines inside of eyelids

50
Q

Where does the conjunctiva not cover?

A

Cornea

51
Q

What is the limbus?

A

Junction of the conjunctiva with the cornea

52
Q

What is conjunctivitis?

A

Inflammation of conjunctiva

53
Q

How do we see?

A

Light enters eye

Refracted on to a focal point

54
Q

What structures refract light?

A

Cornea
Tear film
Lens
Aqueous + vitreous humour

55
Q

What is myopia?

A

Short-sightedness

56
Q

What is hypermetropia?

A

Long-sightedness

57
Q

What is the accommodation reflex?

A

Focusing near objects requires greater refraction of light so eye accomadates

58
Q

How does the eye accommodate?

A

Pupil constricts
Eyes converge
Lens becomes more biconvex - contraction of ciliary muscle

59
Q

What is presbyopia?

A

Age-related inability to focus near objects

60
Q

What types of cells are present on the retina?

A

Rods

Cones

61
Q

What do rods do?

A

Active at low light levels

Do not mediate colour vision

62
Q

Where do rods lie?

A

Peripheral parts of retina

63
Q

What do cones do?

A

High definition

Colour vision

64
Q

Where do cones lie?

A

Concentrated in macula

65
Q

What is the fovea?

A

Area of only cones

66
Q

How are visual action potentials generated?

A

Action potentials generated in response to light via retinal ganglion cells

RGC axons collect in area of optic disc forming optic nerve

Action potentials follow visual pathway to occipital lobe

67
Q

What can cause blurring of vision?

A

Transparency of structures anterior to retina
- cataract

Ability of structures to refract light

  • astigmatism
  • presbyopia

Retina

  • retinal detachment
  • macular degeneration
  • optic neuritis
68
Q

How is the shape of the eyeball maintained?

A

Chambers filled with fluid

  • anterior and posterior
  • vitreous
69
Q

What fills the anterior and posterior chambers?

A

Aqueous humour

70
Q

What is aqueous humour?

A

Fluid produced by ciliary processes within ciliary body

71
Q

What is the flow of aqueous humour?

A

Flows from ciliary body

Posterior chamber

Anterior chamber

Drains through iridocorneal angle

72
Q

Where does aqueous humour drain?

A

Via trabecular meshwork into canal of Schlemm

73
Q

What is glaucoma?

A

Optic nerve damage secondary to raised intraocular pressure

74
Q

What is chronic glaucoma also known as?

A

Open-angle glaucoma

75
Q

What happens in chronic glaucoma?

A

Trabecular meshwork deteriorates as we age

Increased intraocular pressure = increased optic disc cupping

Gradual loss of peripheral vision

76
Q

What is acute glaucoma also known as?

A

Closed-angle glaucoma

77
Q

What happens in acute glaucoma?

A

Narrowing of iridocorneal angle

78
Q

What is the relevance of acute glaucoma?

A

Ophthalmological emergency

79
Q

What are the signs of acute glaucoma?

A
>55
Acutely painful red eye 
Irregular oval pupil 
Blurring of vision 
N+V
80
Q

How is acute glaucoma managed?

A

Drugs to reduce intraocular pressure then surgery

81
Q

What is astigmatism?

A

Irregularity of corneal surface