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NEURO > Common Conditions of the eye > Flashcards

Common Conditions of the eye Flashcards

1
Q

what can blunt trauma do to the eye cause

A

blow out fracture

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2
Q

how does a blow out fracture occur

A

rim is strong (as are lateral and superior walls) –can withstand force (don’t usually fracture) – but rest of walls are thin- can easily fracture – leading to herniation of contents into surrounding sinuses – “blown out fracture

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3
Q

what causes a tear drop sign x-ray

A

Orbital floor fracture – herniation into maxillary sinus

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4
Q

how does an orbital floor fracture cause abnormal eye movement

A

muscles tethered due to herniation - not paralysis of muscles due to nerve damage

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5
Q

how does a blow out fracture cause abnormal eye movement

A

can cause damage to CNIII from infraorbital foramen - also reduced sensation to this area

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6
Q

what does increased orbital fat cause

A

hypertrophied orbital fat in certain conditions (e.g. thyroid diseases) lead to staring appearance - scleral show (sclera can be seen above and below cornea)

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7
Q

what can cause infection of the cavernous sinus

A

popping pimples in the “danger zone” of the face - infection picked up by emissary veins - leads to infection of the cavernous sinus

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8
Q

what can infection of the cavernous sinus lead to

A

cavernous sinus thrombosis - can spread infection directly to the brain

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9
Q

how can cavernous sinus infection cause eye symptoms

A

venous drainage of the orbit is into the cavernous sinus - infection of the cavernous sinus compromises venous drainage - leads to engorged tortuous veins and engorged and swollen optic disc

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10
Q

why can some patients not move their eye when they have infection of the cavernous sinus

A

infection causes swelling of eye - can affect nerves

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11
Q

what is a coloboma

A

hole in one of the structures of the eye - iris, retina, choroid or optic disc

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12
Q

what embryological abnormality leads to a coloboma forming

A

when the choroidal fissure doesn’t fuse

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13
Q

what is retinal detachment

A

when the inner 9 layers of the retina detach from the external 10th layer (pigment epithelial layer)

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14
Q

what embryological feature can cause retinal detachment

A

coloboma

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15
Q

how can blunt trauma to the eye cause retinal detachment

A

trauma causes peripheral retina to tear - vitreous gel liquifies - liquid vitreous pushes through the retinal tear and detaches it

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16
Q

what are the conjunctiva of the eye

A

a thin vascular membrane that covers the inner surface of the eyelids and loops back over the sclera - DOES NOT COVER THE CORNEA

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17
Q

what is conjunctivitis

A

self limiting bacterial or viral infection of the conjunctiva

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18
Q

what are symptoms of conjunctivitis

A

red, watering eyes, + discharge - blurred vision but no loss of vision as long as infection does not spread to cornea

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19
Q

how can you treat conjunctivitis

A

antibiotic eye drops if likely to be bacterial

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20
Q

what might cause the appearance of a drooping eyelid (ptosis)

A

CNIII dystrophy or paralysis - levator palpebrae superioris affected

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21
Q

what might cause the inability to close the eyelid

A

if on right side - left facial nerve paralysis

might see mouth drooping too

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22
Q

what are the two types of stye that can occur

A

external - hordeolum external

internal - hordeolum internum

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23
Q

what causes an external stye

A

occurs due to infection of hair follicle of the eyelash – sebaceous gland

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24
Q

what causes an internal stye

A

occurs due to blockage and infection of the meibomian glands

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25
Q

how can styes be treated

A

warm compress, eyelid hygiene, may need surgical incision and curettage

26
Q

what are the 5 layers of the cornea

A
  1. epithelium - stratified squamous non-keratinised
  2. bowmans membrane - basement membrane of corneal epithelium
  3. stroma - regularly arranged collagen (no blood vessels)
  4. descemets layer
  5. endothelium - single layer
27
Q

what are the two type of corneal pathology

A
  1. inflammatory - eg corneal ulcer

2. non-inflammatory - eg corneal dystrophies

28
Q

what do corneal pathologies frequently lead to

A

opacification of the cornea - may need to be treated by corneal transplant

29
Q

what can cause corneal ulcers

A

infections - viral/bacterial/fungal
- needs aggressive treatment to prevent further spread and scarring

non-infectious - trauma, corneal degenerations, dystrophy

30
Q

what are the 5 common aspects of corneal dystrophies

A
  1. bilateral
  2. opacifying
  3. non-inflammatory
  4. mostly genetically determined
  5. sometimes due to accumulation of substances such as lipids within cornea
31
Q

what is the clinical presentation of corneal dystrophy

A
  • presents in 1st-4th decade
  • most commonly - decreased vision
  • start in one layer of the cornea and spread to others
32
Q

why is the cornea “immune privileged”

A

it is avascular

33
Q

what is a cataract

A

lens opacification

34
Q

how do cataracts develop

A

older (embryological, foetal) fibres never shed - compacted in the middle of the lens

no blood supply to lens - depend entirely on diffusion for nutrition

absorb harmful UV rays - prevent retina damage BUT get damaged themselves - damaged lens fibres - opaque - cataract

35
Q

what is the management of cataracts

A

eye drops DO NOT work

surgery - small incision - lens capsule opened - cataracts lens removed by emulsification - plastic lens* placed in capsular bag

PCIOL - posterior chamber intra ocular lens

36
Q

what is glaucoma

A

raised intraocular pressure

37
Q

what are the two types of glaucoma

A
  1. primary open angle glaucoma (POAG) (most common)

2. angle closure glaucoma

38
Q

what does open/closed angle refer to

A

the angle of the anterior chamber and trabecula meshwork - i.e. is the angle of the anterior chamber blocking schlemms canal for drainage of fluid

39
Q

how is the drainage blocked in open angle glaucoma

A

not an anatomical blockage - drainage canals are like a clogged drain - build up of particles over a long time - aqueous can’t drain

40
Q

how is the drainage blocked in closed angle glaucoma

A

anatomical blockage - event on a predisposed eye leads peripheral iris to physically block angle - aqueous can’t drain

41
Q

what are the consequences of raised intraocular pressure (IOP)

A

pressure on nerve fibres on surface of retina - cause them to die = visual field defects

ultimately all nerve fibres lost = blindness

42
Q

what would raised IOP show on ophthalmoscopy

A

optic disc appears unhealthy, pale and cupped

43
Q

what are the triad signs of glaucoma

A
  1. raised IOP
  2. visual field defects
  3. optic disc changes on ophthalmoscopy
44
Q

what is the management for primary OPEN angle glaucoma

A
  1. eye drops to decrease IOP - prostaglandin analogues, beta-blockers, carbonic anhydrase inhibitors
  2. laser trabeculoplasty
  3. trabeculectomy surgery
45
Q

how does the IOP progress in open angle glaucoma

A

GRADUAL, painless build up of IOP

46
Q

what are the symptoms of CLOSED angle glaucoma

A

SUDDEN ONSET - painful, vision lost/blurred, headaches

47
Q

what would be seen on examination of CLOSED angle glaucoma

A

red eye, cornea often opaque as raised IOP drives fluid into cornea - anterior chamber shallow, angle closed, pupil mid dilated

48
Q

what are three mechanism that cause a closed angle

A
  1. Functional block in a small eye – large lens
  2. Mid-dilated pupil  periphery of iris crowds around angle and outflow is obstructed
  3. Iris sticks to pupillary border (synechia) which prevents reaching AC. Leads to iris balooning anteriorly and obstructing angle.
49
Q

what is the management for closed angle glaucoma

A
  1. decrease IOP
    - infusion with or without oral therapy - carbonic anhydrase inhibitors (acetazolamide)
    - analgesics, antiemetics
    - constrictor eye drops
    - if no c-i beta blockers e.g. timolol
  2. iridotomy (laser) - both eyes - to bypass blockage
50
Q

what is the role of the choroid

A

Supplies blood to outer layers of retina

51
Q

what is the role of the iris

A

Controls the diameter of the pupil and thereby controls the amount of light rays entering the eyeball

52
Q

what is another name for the vascular layer of the eye

A

uvea

53
Q

what is uveitis

A

inflammation of the uvea (vascular layer) of the eye

54
Q

what are the 3 types of uveitis

A
  1. anterior - iris with or without inflamed ciliary body
  2. intermediate - inflamed ciliary body
  3. posterior - inflamed choroid
55
Q

what are the 4 groups uveitis can occur in

A
  1. Isolated illness
  2. Non-infectious autoimmune causes – eg: presence of HLA-B27 predisposes to anterior uveitis
  3. Infectious causes – chronic diseases such as TB
  4. Associated with systemic diseases – eg: ankylosing spondylosis
56
Q

what is the pathophysiology of anterior uveitis

A

inflamed anterior uvea (iris) leaks plasma and WBC into aqueous humour - seen during split lamp examination as a hazy AC - cells deposited at back of cornea

cells in AC may settle inferiorly - hypopyon

57
Q

what are the symptoms of anterior uveitis

A

eye is red and painful, visual loss

58
Q

what is the pathophysiology of intermediate uveitis

A

ciliary body inflamed - leaks cells and proteins into vitreous humour - leads to hazy vitreous

59
Q

what are the symptoms of intermediate uveitis

A

patients complain of “floaters” and hazy vision

60
Q

what is the pathophysiology of posterior uveitis

A

inflamed choroid sitting under retina - inflammation spreads to retina and causes blurred vision

NEURO (51 decks)

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