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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
how can styes be treated
warm compress, eyelid hygiene, may need surgical incision and curettage
26
what are the 5 layers of the cornea
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
what are the two type of corneal pathology
1. inflammatory - eg corneal ulcer | 2. non-inflammatory - eg corneal dystrophies
28
what do corneal pathologies frequently lead to
opacification of the cornea - may need to be treated by corneal transplant
29
what can cause corneal ulcers
infections - viral/bacterial/fungal - needs aggressive treatment to prevent further spread and scarring non-infectious - trauma, corneal degenerations, dystrophy
30
what are the 5 common aspects of corneal dystrophies
1. bilateral 2. opacifying 3. non-inflammatory 4. mostly genetically determined 5. sometimes due to accumulation of substances such as lipids within cornea
31
what is the clinical presentation of corneal dystrophy
- presents in 1st-4th decade - most commonly - decreased vision - start in one layer of the cornea and spread to others
32
why is the cornea "immune privileged"
it is avascular
33
what is a cataract
lens opacification
34
how do cataracts develop
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
what is the management of cataracts
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
what is glaucoma
raised intraocular pressure
37
what are the two types of glaucoma
1. primary open angle glaucoma (POAG) (most common) | 2. angle closure glaucoma
38
what does open/closed angle refer to
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
how is the drainage blocked in open angle glaucoma
not an anatomical blockage - drainage canals are like a clogged drain - build up of particles over a long time - aqueous can't drain
40
how is the drainage blocked in closed angle glaucoma
anatomical blockage - event on a predisposed eye leads peripheral iris to physically block angle - aqueous can't drain
41
what are the consequences of raised intraocular pressure (IOP)
pressure on nerve fibres on surface of retina - cause them to die = visual field defects ultimately all nerve fibres lost = blindness
42
what would raised IOP show on ophthalmoscopy
optic disc appears unhealthy, pale and cupped
43
what are the triad signs of glaucoma
1. raised IOP 2. visual field defects 3. optic disc changes on ophthalmoscopy
44
what is the management for primary OPEN angle glaucoma
1. eye drops to decrease IOP - prostaglandin analogues, beta-blockers, carbonic anhydrase inhibitors 2. laser trabeculoplasty 3. trabeculectomy surgery
45
how does the IOP progress in open angle glaucoma
GRADUAL, painless build up of IOP
46
what are the symptoms of CLOSED angle glaucoma
SUDDEN ONSET - painful, vision lost/blurred, headaches
47
what would be seen on examination of CLOSED angle glaucoma
red eye, cornea often opaque as raised IOP drives fluid into cornea - anterior chamber shallow, angle closed, pupil mid dilated
48
what are three mechanism that cause a closed angle
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
what is the management for closed angle glaucoma
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
what is the role of the choroid
Supplies blood to outer layers of retina
51
what is the role of the iris
Controls the diameter of the pupil and thereby controls the amount of light rays entering the eyeball
52
what is another name for the vascular layer of the eye
uvea
53
what is uveitis
inflammation of the uvea (vascular layer) of the eye
54
what are the 3 types of uveitis
1. anterior - iris with or without inflamed ciliary body 2. intermediate - inflamed ciliary body 3. posterior - inflamed choroid
55
what are the 4 groups uveitis can occur in
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
what is the pathophysiology of anterior uveitis
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
what are the symptoms of anterior uveitis
eye is red and painful, visual loss
58
what is the pathophysiology of intermediate uveitis
ciliary body inflamed - leaks cells and proteins into vitreous humour - leads to hazy vitreous
59
what are the symptoms of intermediate uveitis
patients complain of "floaters" and hazy vision
60
what is the pathophysiology of posterior uveitis
inflamed choroid sitting under retina - inflammation spreads to retina and causes blurred vision

NEURO (51 decks)

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