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Head and Neck > Eye > Flashcards

Eye Flashcards

1
Q

What are the bones forming the walls of the orbit

A 
Ethmoid
Maxilla
Zygomatic
Lacrimal
Frontal
Sphenoid
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2
Q

Why are some aspects of the walls vulnerable to fracture

A

Sinuses next to floor and medial wall causes weakness

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3
Q

What is a blow out fracture

A

Sudden increase in intra orbital pressure which fractures the floor. This causes prolapse into medullary sinus and tethers the eye from the bottom so cannot look up.

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4
Q

Why with a blow out can you get numbness over the cheek, upper lip and eyelid

A

Disruption to cutaneous nerve Vb

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5
Q

Where does the eye get its blood suppy

A

1st branch of ICA
Ophthalmic artery
Gives off central retinal after going through optic canal and this supplies retina and chorioid layer
Ciliary artery feeds choroid layer.

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6
Q

What happens if there is central retinal artery occlusion

A

Cherry red spot where macula is thinnest as choroid layer is still being perfused by ciliary artery.

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7
Q

Why does infection to eye pose threat of spreading

A

Ophthalmic veins drain into cavernous sinus, pterygoid plexus and facial vein

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8
Q

What muscle and nerve closes the eye

A

CN7 palpable part of orbicularis oculi

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9
Q

What muscle and nerve contracts and elevates the eyelid

A

Levator palpebrae- CN3

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10
Q

What is the function of the meibomian gland

A

Oily substance to prevent evaporation of tear film.

In tarsal plates

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11
Q

Function of orbital septum

A

Barrier against superficial infection spreading pre septal to post septal

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12
Q

Where is humour made and when does it go

A

Maid in ciliary processes in ciliary body. flows posterior to anterior draining through iridocorneal angle via trabecular meshwork into canal of schlemm to venous circulation

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13
Q

Where does vitreous humour fill

A

Intraocular

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14
Q

Aqueous humour

A

fills anterior and posterior chambers providing O2 and nutrients to lens and cornea.

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15
Q

What is the function of the lacrimal apparatus

A

Tear film production and drainage

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16
Q

What is epiphora

A

Overflow due to obstruction of nasolacrimal duct

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17
Q

What are the 3 layers of the eyeball

A

Sclera
Choroid
Retina - innermost layer

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18
Q

What is the macula densa

A

Dense area of photoreceptors- cones for high acuity of colour vision
The thinnest part of retina
Light is focused here

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19
Q

What helps refract light

A

Tear film, cornea, lens and humour

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20
Q

What helps regulate light entry

A

Pupil

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21
Q

What causes long sight

A

Hypermetropic- eyeball to short

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22
Q

What causes short sight

A

Myopic- eyeball to long

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23
Q

What is the Accommodation reflex

A

Eye restricts pupil and converge to stay fixed on same point. Lens becomes biconvex- fatter

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24
Q

How does the lens change shape

A

Contraction of ciliary muscles under parasympathetic oculomotor control leads to fatter. Relaxation means ligaments are pulled tight = lens flattens.

25
Q

What is the fovea

A

Place with only cones

26
Q

What causes blind spot

A

Optic disc has no photoreceptors

27
Q

What does pinhole testing do

A

Sees if there is a refractive error or not

28
Q

Difference between styes and meibomian cyst

A

Painful, superficial, blocked sebacceous ? staph VS painless blocked meibomian gland

29
Q

What is blepharitis

A

Inflammation of lids, gritty

30
Q

What is conjunctivitis

A

Inflammation of conjunctiva viral or bacterial.

31
Q

What are cateracts

A

Decrease transparency of structures anterior to retina. Decreases refractive ability.

32
Q

What is presbyopia

A

Lens stiffer with age
Less able to change shape
Near objects hard to focus on

33
Q

What are the two types of glaucoma

A

Acute vs Chronic

34
Q

What is the issue in glaucoma

A

Blockage of drainage of aqueous humour from anterior chamber = increased intraocular pressure.

35
Q

Explain chronic glaucoma

A

Open angel
Trabecular meshwork deteriorates with age
Increased intraocular pressure
Disc cupping
Gradual loss of peripheral vision due to ischemia and damage to optic nerve

36
Q

Explain acute glaucoma

A

Closed angle
Narrowing of iridocorneal angle
Emergency
Halo- corneal edema

37
Q

What changes do you see in Papilledema

A

Disc swelling secondary to raised intracranial pressure
Bilateral
Optic nerve swelling

38
Q

What changes do you see in glaucoma

A

Disc cupping

Increased cup to disc ratio caused by high pressures in the eye

39
Q

Why do we have binocular vision

A

Wider field of vision

Depth perception

40
Q

What does misalignment of visual axis cause

A

Image focuses of different areas of retina. Image cannot be fused = double vision - diplopia

41
Q

What are the extraocular muscles

A

S,M,L,I rectus

SO and IO

42
Q

What is the origin for all but IO muscle

A

Apex of orbit

43
Q

Where does the IO muscle arise

A

Floor of orbital cavity

44
Q

What is the action of the SO

A

Intort, depress and slightly abduct

45
Q

When is the SO most powerful

A

Medially

46
Q

What does the IO do

A

Extort, elevate, abducts

47
Q

When is the IO most powerful

A

Medially

48
Q

What is the action of S recuts

A

Elevation, slight adduction, slight intorsion

49
Q

When is S rectus most powerful

A

Laterally

50
Q

What is the action of I rectus

A

Depression, slight adduct, slight extort

51
Q

When is I retus most powerful

A

Laterally

52
Q

Why do we perform a H in eye exam

A

To isolate muscles to test individually as some share common action but each has a place where it’s more dominant

53
Q

What is Stabismus

A

Ocular misalignment- common in children

54
Q

What is the innervation of LR

A

CN6

55
Q

What is the innervation of SO

A

CN4

56
Q

What is the innervation of the rectus and IO

A

CN3

57
Q

What else does CN3 innervate

A

Sphincter pupillae muscles and levator palpebrae superioris

58
Q

In compressive lesion is the pupil spared

A

No, its involved

Head and Neck (15 decks)

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