The eye Flashcards

1
Q

Fill in the table

A
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2
Q

What condition is this

A

Exophthalmos

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3
Q

What condition is this

A

Enophthalmos

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4
Q

What condition is this

A

Hydrophthalmos

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5
Q

What condition is this

A

Microphthalmos

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6
Q

Label the eye

A
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7
Q

Label the eye

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8
Q

Label the eye

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9
Q

Label the eye

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10
Q

Label the eye

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11
Q

Describe differences between herbivore & carnivore eye

A
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12
Q

Name the muscles of the eye

A
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13
Q

Label muscles 1-7

A
  1. Dorsal Oblique
  2. Lateral rectus
  3. Ventral oblique
  4. Ventral rectus
  5. Medial rectus
  6. Dorsal rectus
  7. Retractor bulbi
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14
Q

What passes through the optic foramen?

A

Optic nerve
Internal ophthalmic artery
Trochlear nerve

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15
Q

What passes through the orbital fissure

A

Abducens nerve
Oculomotor nerve
Ophthalmic nerve

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16
Q

Describe blood supply to the eye

A

Ophthalmic artery which comes from the internal carotid artery

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17
Q

Describe venous drainage of the eye

A

Through vortex veins and orbital venous plexus
Or
Ophthalmic vein
All eventually drain into external jugular vein

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18
Q

Fill in the table about globe position

A
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19
Q

Define aniscoria

A

Unequal pupil sizes

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20
Q

Define miosis

A

Constricted pupils

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21
Q

Define mydriasis

A

Dilated pupils

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22
Q

Define strabismus

A

Eyes point in different directions

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23
Q

Define nystagmus

A

Repetitive & involuntary movement of eye

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24
Q

What are the 3 layers of the eyelid

A
  1. eyelid skin
  2. Levator palpebrae superioris muscle
  3. Palpebral conjuctiva
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25
Q

What muscles open the eye

A

Levator palpebrae superioris
Muller muscle

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26
Q

What muscle closes the eye

A

Orbicularis oculi

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27
Q

What are Meibomian glands

A

Modified sebaceous glands
20-40 per eye
Produce meibum (lipid part of tear film)

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28
Q

What are the functions of the eyelid

A

Protect eye from trauma
Blink to distribute & drain tear film & physical removal of debris
Contribute to tear film

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29
Q

What are the functions of the third eyelid

A

Protect ocular surface
Distribute tear film & remove debris
Aqueous production of tear film
Contain IgA secreting plasma cells for ocular defence

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30
Q

Label the conjunctiva

A
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31
Q

Describe the relationship between bulbar conjunctiva & sclera

A

Finer branching conjunctival vessels overlie larger, straighter episcleral vessels

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32
Q

What is entropion

A

Inversion of all or parts of eyelid margin (common in Bulldogs)

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33
Q

What is ectropion

A

Outward turning of eyelid

34
Q

What is macropalpebral fissure

A

Big eyelid opening - can barely blink

35
Q

Label the conditions of the cilia

A
36
Q

What is a prolapsed nictitans gland

A

Common, also known as cherry eye
Breed related
Requires surgery

37
Q

What is scrolled cartilage

A

Abnormal growth (cartilage too big for third eyelid
Usually requires surgery

38
Q

What is conjunctivitis

A

Swelling of conjunctive & discharge seen

39
Q

What are the 3 layers of the eye

A

Fibrous (outer) layer - sclera & cornea
Vascular (middle) layer - uveal tract
Neuroectodermal (inner) layer - retina & optic nerve

40
Q

What are the components of tear film

A

Lipid, aqueous, mucin & epithelium

41
Q

Describe the origin of tear film

A

Lipid layer - meibomian glands
Aqueous layer - orbital layer (70%) & nictitands glands (30%)
Mucin layer - Conjunctival goblet cells

42
Q

Label the layers of the cornea

A
43
Q

What are the functions of the cornea

A

Refract & transmit light
Tensile strength
Protection

44
Q

What is keratoconjunctivitis sicca

A

Inadequate tear production
Schirmer tear test <15mm/min
Common in Cocker Spaniels & toy breeds

45
Q

What are corneal ulcers

A

Break in continuity of corneal epithelium with exposure of underlying stroma
Fluorescein staining used for diagnosis (Descemets membrane doesn’t take up stain)
Can be superficial, deep or descemetocoele

46
Q

What are some causes of corneal ulcers

A

Trauma, eyelid abnormalities, eyelash lesions, infections, keratoconjunctivitis sicca (KCS)

47
Q

Describe corneal wound healing

A

Self renewing
1. Proliferation of basal epithelial cells at limbus
2. movement of peripheral cells towards cornea centre
3. epithelial cells lost from corneal surface into tear film

48
Q

Describe corneal opacities

A
49
Q

Label the eye

A
50
Q

What is the function of the iris

A

controls amount of light entering eye
Forms part of blood ocular barrier

51
Q

What are the functions of the ciliary body

A

Production & drainage of aqueous humour - maintains intraocular pressure, provides nutrition to lens & fills anterior chamber
Anchors lens zonules & provides accommodation (focusing)
Contributes blood ocular barrier
Provides blood & nerve supply to anterior segment

52
Q

What is the function of the choroid

A

Blood supply of retina
Part of blood ocular barrier

53
Q

What is uveitis

A

Inflammation of uvea
Early diagnosis essential to prevent blindness
Clinical signs include: pain, red eye, low intraocular pressure, inflammation in anterior chamber
Causes: trauma, infection, immune-mediated, metabolic, neoplasia

54
Q

What is blepharospasm

A

squinting

55
Q

What is epiphora

A

Excess tears

56
Q

What is glaucoma

A

Raised intraocular pressure due to reduces drainage of aqueous humour
Diagnosed by raised intraocular pressures
Normal values: 10-25mmHG in dogs/cat, 15-20mmHG in rabbit
Measured using Schiotz tonometry, Tonovet or Tonopen
Acute clinical signs: pain, corneal oedema, vision loss, fixed dilated pupil
Chronic clinical signs: globe enlargement, corneal changes, lens luxation, cataracts, blindness

57
Q

Describe lens fibres

A

Thick centres & tapered ends
Fibres cant meet in single point as there isnt enough space so meet in Y shaped pattern

58
Q

Describe lens composition

A

35% protein - crystallins (soluble) & albuminoids (insoluble)
65% water

59
Q

Describe lens function

A

Refractive power of eye
Accommodation
Blocking UV light from retina (prevents damage)

60
Q

Describe vitreous humour anatomy

A

Gel between retina & lens
Largest ocular structure
Transparent so light can get through
Avascular
99% water, 1% protein/cells

61
Q

Describe vitreous humour function

A

Shock absorption
Remove waste products
Maintain intraocular anatomy

62
Q

What is nuclear sclerosis

A

Secondary lens fibres continue to form throughout life
Finite space within eye so progressive compression of nucleus
Older fibres are denser and less transparent so nucleus becomes sclerotic (hardened)
Normal ageing process
Appears as greyish-blue haze

63
Q

What is lens subluxation

A

Weakening of zonules
cresent around lens
Full lens luxations can be posterior or anterior

64
Q

Label the layers of the posterior segment of the eye

A
65
Q

What is retinal pigment epithelium

A

Outermost layer of retina
Single layer of cells
Has photoreceptors embedded within it (rods & cones)

66
Q

What are the functions of retinal pigment epithelium

A

Recycle used photopigments
Store vitamin A
Form part of blood-retinal barrier

67
Q

What are cones & rods

A

Cones = color vision
Rods = night vision

68
Q

What is the function of the retina

A

Absorbs light rays & converts light energy into electrical energy which travels as nerve impulse up optic nerve to visual cortex

69
Q

Label the diagram

A
70
Q

What are the 3 regions of the optic nerve

A

Intraocular
Retrobulbar (orbit)
Intracranial (brain)

71
Q

Describe blood supply to the retina

A

Dual blood supply due to high metabolic rate
Inner retina: retinal blood vessels
Outer retina: choroidal blood vessels

72
Q

What is the tapetum

A

Part of choroid, lies behind retina
shiny reflective layer
reflects light rays so retina receives light twice

73
Q

What is the fundus

A

Portion of posterior segment of eye that is viewed with ophthalmoscope

74
Q

Label the eye

A
75
Q

Label the eye

A
76
Q

How does the fundus form

A

Sclera –> Choroid & tapetum –> RPE –> neural retina –> final

77
Q

What animal does this fundus belong to

A

Cat

78
Q

What animal does this fundus belong to

A

Dog

79
Q

What animal does this fundus belong to

A

Ox, sheep or goat

80
Q

What animal does this fundus belong to

A

Horse