Vision Flashcards

1
Q

Conjunctiva

A

mucosal epithelium that forms a sac when eyes are shut
covers sclera
secretes mucous
lubricates surface

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2
Q

Disorders of the conjunctiva

A

conjunctivitis

pinguecula

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3
Q

conjunctivitis

A

disorder of conjunctiva
dry eye
allergies
viral and bacterial infections

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4
Q

Pinguecula

A

disorder of conjunctiva

degeneration of conjunctiva

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5
Q

Cornea

A

transparent part of the eye
powerful refractive component 2/3 eye power
Five layers
flattens in periphery to improve imager and reduce aberrations
flattest at horizontal meridian

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6
Q

Layers of the cornea

A
five: 
epidermis - healing 
stroma - collagen, transparency 
endothelium - maintain transparency 
bowman's - collagen 
Descemet's - basement membrane
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7
Q

Disorder of cornea

A

Keratitis

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8
Q

Keratitis

A

inflamed cornea

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9
Q

Sclera

A
white part of eye
blue in young - collagen disease
yellow in elderly - jaundice / lipid deposits
protects and supports eyeball 
three layers
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10
Q

layers of the sclera

A

three:
episclera - blood vessels
stroma - irregular collagen fibres (opaque)
lamina fusca - thin pigmented connective tissue

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11
Q

disorders of the sclera

A

episcleritis

scleritis

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12
Q

Episcleritis

A

harmless form of red eye

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13
Q

scleritis

A

painful red eye which can damage sight

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14
Q

limbus

A

transition zone between cornea and sclera

aqueous humour drainage via the trabecular meshworks

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15
Q

Aqueous humor

A

transparent blood like fluid
feeds cornea and crystalline lens
secreted by ciliary processes

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16
Q

disorders of the limbus

A

glaucoma

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17
Q

glaucoma

A

blockage of the trabecular meshworks

exaggerated cupping

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18
Q

tonometry

A

measures IOP

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19
Q

keratometry

A

measure curvature of cornea

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20
Q

iris

A

vascular layer of the eye
coloured (melanin)
forms pupil which controls light entering eye

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21
Q

sphincter pupillae

A

constricts pupil

miosis

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22
Q

dilator pupillae

A

dilates pupil

mydriasis

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23
Q

disorders of the iris

A

iritis

occurs with anterior uveitis

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24
Q

iritis

A

very serious red eye

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25
Q

uveal tract

A

iris
ciliary body
choroid

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26
Q

retina

A

macula
fovea
optic disc

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27
Q

ciliary body

A

ring of tissue
vascular layer
ciliary muscle and process

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28
Q

ciliary muscle

A

focus eye (accomodation) via attachments to lens

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29
Q

ciliary process

A

secrete aqueous humour

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30
Q

disorders of the ciliary body

A

anterior uveitis

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31
Q

anterior uveitis

A

red eye

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32
Q

anti-glaucoma drugs

A

reduce aqueous humour production

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33
Q

choroid

A

posterior vascular layer
three layers:
bruch’s membrane - passes material to and from retina
vascular layer - nourish retina / blood supply
suprachoroid - melanin / absorbs stray light

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34
Q

disorders of the choroid

A

choroiditis (with posterior uveitis)

macular degeneration

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35
Q

choroiditis

A

with posterior uveitis
inflammation of choroid
threat to sight

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36
Q

macular degeneration

A

caused by dysfunction of bruch’s membrane

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37
Q

retina

A

inner neural layer
layer include:
retinal pigement epithelium - nourish photo receptors
photo receptors - rods in periphery, cones in fovea, bipolar and ganglion integrate and process photo receptor signals

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38
Q

cones

A

in fovea
object identification
high resolution
colour vision

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39
Q

rods

A

in periphery
object detection
high sensitivity
contrast, brightness, motion

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40
Q

disorders of the retina

A

retinal detachment
diabetic retinopathy
hypertensive retinopathy
macular degeneration

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41
Q

crystalline lens

A

refractive component - variable - 1/3 eye power
flatter in periphery
grows through life

made up of:
lens capsule - changes shape / accommodation
cortex - youngest lens fibres
nucleus - oldest fibres

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42
Q

what maintains the transparency of the crystalline lens

A

crystallins
regular arrangement on lens fibres
lack of organelles
antioxidants

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43
Q

disorders of the crystalline lens

A

cataract

presbyopia

44
Q

cataract

A

transparency mechanism failure

45
Q

presbyopia

A

lens can no longer accommodate

46
Q

optic nerve head

A

ganglion nerve fibres take signals to brain

cupped

47
Q

arteries

A

enter eye

48
Q

veins

A

leave eye

49
Q

blind spot

A

absent photo receptors

50
Q

disorders of the optic nerve head

A

glaucoma

51
Q

brain disease

A

pallor / swelling of optic nerve

52
Q

vitreous body

A

transparent gel
mechanically supports lens and retina
refractive component

53
Q

disorders of the vitreous body

A

vitreous syneresis

posterior vitreous detachment

54
Q

vitreous syneresis

A

vitreous breakdown with age (floaters)

55
Q

posterior vitreous detachment

A

vitreous detaches at the retina

large floaters and light flashes

56
Q

Aqueous humour production

A

in ciliary processes
1. blood plasma leaks into stroma
2. ciliary body epithelium absorbs plasma and generates bicarbonate ions using carbonic anhydrase
3. Na/K+ pump moves Na+ out
4. bicarbonate ions drawn out by Na+
5. plasma drawn out by bicarbonate ions
REGULATED BY: sympathetic nervous system action on adenylate cyclase

57
Q

IOP

A

10-21 mmHg
higher on a morning
3-6 mmHg variation is normal

58
Q

Aqueous humour drainage

A

trabecular overflow 80-90% meshworks
uvescleral outflow 10-15% via ciliary body surface into choroid veins
iris route - small % via iris surface

59
Q

lacrimal glands

A

orbital
paleprabral
tear production

60
Q

Tear drainage

A
orbicularis oculi
puncta
lacrimal sac
lacrimal caniculi 
nasolacrimal duct
61
Q

orbicularis oculi

A

tear pump

62
Q

Tear layers

A
  1. outer lipid layer - delays evaporation and lubricates
  2. middle aqueous layer - provides o2, defends surface
  3. inner mucin layer - lubricates
63
Q

types of tear flow

A
sympathetic = blood vessels supplying glands
parasympathetic = myoepithelial cells
normal = sympathetic, light and pollution
emotional = parasympathetic, emotional state via emotion centres
reflex = parasympathetic, irritation of cornea
crocodile = parasympathetic, faulty connection to lacrimal and not salivary gland
64
Q

orbit bones

A
  1. frontal
  2. zygomatic
  3. maxillary
  4. sphenoid
  5. ethmoid
  6. palatine
  7. lacrimal
65
Q

canals

A

optic
superior orbital fissure
inferior orbital fissure

66
Q

sinuses

A

frontal
sphenoid
ethmoid air cells
maxillary

67
Q

Extra ocular muscles

A
4 recti:
superior 
medial
lateral 
inferior

2 obliques:
superior
inferior

1 muscle to raise eyelid:
levator palebra superioris

68
Q

meibomian gland

A

secretes tears to prevent dry eyes

69
Q

tarsal muscles

A

opens eye wide with fear

70
Q

strabismus

A

squint

71
Q

amblyopia

A

lazy eye

72
Q

disorders of eye muscles

A

strabismus

amblyopia

73
Q

disorders of the eyelids

A

blepharitis
chalazion
ectropion

74
Q

blepharitis

A

dandruff

75
Q

chalazion

A

lump caused by infected lash or gland

76
Q

ectropion

A

eyelid turned inside out

77
Q

simplified visual pathway

A
  1. retina
  2. optic nerve
  3. optic chiasm
  4. optic tract
  5. lateral geniculate nucleus
  6. optic radiation
  7. visual cortex - V1
78
Q

afferent light reflexes

A
light 
ganglion cells in retina
chiasm
both optic tract
leave before LGN
synapse at pretectal nuclei in superior colliculus both sides
79
Q

efferent light reflexes

A
pretectal nuclei
internunclial nerve
both accessory oculomotor nerve nuclei
parasympathetic axons
sphincter pupillae
80
Q

afferent - near synkinesis

A
looking from distance to near 
accomodation
convergence 
miosis 
ganglion cells to V1
81
Q

efferent - near synkinesis

A

V1 to frontal eye fields:
1. main ocular nucleus - recti muscles = convergence
OR
2. accessory oculomotor nerves - parasympathetic nerve fibres - ciliary muscle (accommodation) / sphincter pupillae (miosis)

82
Q

arousal / fear dilation

A

sympathetic nerve fibres
superior cervical ganglion
internal carotid artery
dilator pupillae (mydriasis)

83
Q

V1 damage

A

homonymous central hemianopia (macular fibres)

macular sparing homonymous central hemianopia (peripheral retina fibres)

84
Q

V2 damage

A

alexia - cant read
agnosia - cant recognise objects
agraphia - cant write
visual hallucinations

85
Q

bipolar cells

A

transmit info from photoreceptors to ganglion

86
Q

retinal ganglion

A

transmit info retina to brain

87
Q

horizontal cells

A

synapse with photo receptors and alter output

88
Q

amacrine cells

A

synapse with bipolar cells and alter output

89
Q

müller cells

A

support retinal neurons

90
Q

red cones

A

long wavelength

91
Q

green cones

A

medium wavelength

92
Q

blue cones

A

short wavelength

93
Q

Accomodation

A
  1. ciliary muscle contract
  2. tension released on lens attachments
  3. lens surface steepens
  4. lens power is raised
94
Q

emmetropia

A

normal vision

95
Q

myopia

A

short sighted
eye too long or cornea too powerful
focus before retina
corrected with minus lens

96
Q

hyperopia

A

long sighted
eye too short or cornea too weak
focus after retina
correct with plus spheres

97
Q

astigmatism

A

rugby ball shaped eye
poor near and distance vision
two focal points before and after retina
corrected with cylinders

98
Q

presbyopia

A
old eye
reduced ability to accomodate
poor near vision
can reduce distance vision
corrected with near addition plus lens
99
Q

trichromacy
dichromacy
monochromacy

A

normal colour vision
2/3 cones
no cones or 1 cone

100
Q

prot

  • anomaly
  • anopia
A

red

  • cones
  • no cones
101
Q

deuter

  • anomaly
  • anopia
A

green

  • cones
  • no cones
102
Q

trit

  • anomaly
  • anopia
A

blue

  • cones
  • no cones
103
Q

Cataract

A

leading cause of blindness
clouded lens ageing
congenital or injury causes
metabolic, molecular, structural, optical

104
Q

Galucoma

A

optic nerve damage
primary open angle - white and black populations
primary angle closure - asian populations
genetic element
disc cupping large cup to disc ratio
increased IOP

105
Q

Macular degeneration

A

leading cause of blindness in high income countries
Risks: over 50, smoking, genetic, BP, cholesterol, fat, BMI
dry form - most common no treatment
wet form - treated with injection - abnormal vessels
Caused by dysfunction of Bruch’s membrane

106
Q

diabetic retinopathy

A

75% of diabetics
early = non-proliferative
proliferative = neovascularisation