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SS > Opthamology > Flashcards

Opthamology Flashcards

1
Q

Causes of subjunctival heamorrhage

A

Idiopathic but can be after sneezing or vomiting

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2
Q

Key factors in eyelid injuries

A

Restore anatomy
Close in layers
Retain function
Minimise scar

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3
Q

Muscles in charge of ptosis

A

Levator palpebrae superioris

Superior tarsal muscle

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4
Q

Bones of the orbit

A 
Palantine
Ethmoid
Lacrimal
Maxillary
Zygomatic
Frontal
Sphenoid
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5
Q

What are the extra occular muscles?

A

Superior and inferior obliques
Lateral and medial rectus
Superior and inferior rectus

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6
Q

Innervation of occular muscles

A

Occulomotor-inferior oblique, medial, superior and inferior rectus
Trochlear- superior oblique
Abducens- lateral rectus

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7
Q

Muscles of eyelid

A 
Orbicularis oculi (CN7) closes lid
Levator palpebrae (CN3) opens lid
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8
Q

Anatomy of eyelid

A

Tarsal plate-makes it hard to invert

Conjunctiva-lines inside of lid and outside of eyeball and produces mucins

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9
Q

Tear film

A 
10-12 microlitres of fluid on surface of the eye
allows eyelid to flow over eye
3 layers
Mucins
Aqueous
Oil (stops evaporation)
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10
Q

Main lacrimal gland vs accessory lacrimal gland function

A

Main-reflex watering when something is stuck in your eye

Accessory lacrimal gland produce tear film fluid

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11
Q

Where do tears go?

A

Lacrimal canaliculi which then lead into lacrimal sac then lacrimal duct

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12
Q

Difference between cranial nerve three palsy and horners syndrome?

A

Both have pstosis
CN3 palsy: eye turned out and big pupil
Horner’s Syndrome: narrow pupil

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13
Q

Orbital septum

A

White tough barrier between orbit and lid tissues stretching from tarsus to orbital rim-important to determine if inflammation is behind or in front if this

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14
Q

Orbital blow out fracture mechanism

A

Orbital floor cracks under trauma and the contents fall down into maxillary sinus
Gives black eye (haematoma), infraorbital nerve loss, double vision and downgaze or upgaze

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15
Q

Thyroid eye disease mechanism

A

Enlarged extra ocular (recti) muscles push the eyeball out of the socket so it bulges

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16
Q

length of average eye

A

2.5cm

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17
Q

Myopia(short sighted) vs Hyperopia (longsighted) vs astigmatism

A

Myopia- focuses in front of retina
Hyperopia-light focuses behind the retina
Astigmatism-light focuses in lots of different places

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18
Q

Cornea

A

600 microns (viewed with slit lamp)
Epithelial, stroma and endothelium- has an endothelial pump and barrier to pump water out of stroma to dehydrate it (better for light)
No blood vessels
Massive innervation
2/3 of light bending done at cornea (due to curvature and difference in refractive index between air and water)
Fixed power lens

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19
Q

Diseases which affect cornea

A

Corneal dystrophies, scars, keratoconus (cornea looks like a rugby ball), increased thickness

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20
Q

Imaging cornea

A

IVCm confocal
Anterior OCT
Computerised topography
Biomechanical corvis st (air puff)

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21
Q

Keratoconus

A

Multifactorial-familial, eye rubbing, down syndrome
“two hit hypothesis”
Most common cause of corneal transplant
Begins at puberty

22
Q

Lens

A

Variable power lens
Connected to ciliary body by zonules
matrix on outside but mostly cells
Epithelial layer on outside, fibre cells within
Nucleus of lens present at utero-grows cortex during life

23
Q

Cataract

A

precipitation of protein within lens cells
Areas can extend into centre or on edges
Diagnosis-opthalmoscope and slit lamp with reduced visual acuity and lens opacity
usually age related
Treated with phacoemulsification surgery

24
Q

Ciliary body

A

Contains ciliary muscle which surrounds eye and is responsible for accommodation
Relaxed-ciliary muscle at biggest diameter
Contracted-makes lens fatter-when looking at close things
Ciliary epithelium produces aqueous humor which fills area between lens and iris (constant into anterior chamber) drains into trabecular meshwork. Damaged trabecular meshwork = increased ocular pressure

25
Q

Retina components

A

Optic disc with optic nerve and retinal artery

Fovea-centre of visual acuity

26
Q

Retina functions

A

Absorb photons
Turn light into chemical message
Turns chemical message into electrical impulse
Transmits electrical impulse to the brain via ganglion cells

27
Q

Cell types in retina

A

Most posterior = photoreceptors (rods and cones)
Bipolar linker cells
ganglion cells = send impulse to brain

28
Q

Why is the retina back to front

A

Photoreceptors are highest energy consuming cells in the body so need direct contact with endothelial cells which give nutrients and remove waste

29
Q

Central and peripheral retina differences

A

Central-more rods and cones

Peripheral-fewer cones but more rods(good for detecting movement)

30
Q

Fovea optimises light entry?

A 
Bipolar and ganglion cells moved out of the way so light directly hits photoreceptor
Most cones (responsible for visual acuity and colour vision)
31
Q

Macula lutea

A

Pigmented area around fovea containing xanothophyll caratenoids which prevent light damaging foveal cones

32
Q

Optic nerve

A

No photoreceptors
Causes blind spot-covered by binoccular vision
Alongside retinal artery and vein

33
Q

Colour absorbancy

A

Red cone-longest wavelength
Green cone
Blue cone-shortest wavelength

34
Q

Colour blindness

A

More common in males

Most commonly green-red

35
Q

Glaucoma

A

Old age
Specific pattern of axonal loss
elevated intraocular pressure
Visual loss-open angle and closed angle

36
Q

IOP assessment

A

Normal 11-22mmHg

Linked to glaucoma but some people with it have normal pressure

37
Q

Open angle glaucoma

A

Most common

2nd cause of blindness in NZ

38
Q

Closed angle glaucoma

A

only 5% of glaucoma cases
Rapid onset pain and redness
vomitting abdo pain
Mid dilated pupil

39
Q

Optic nerve cupping

A

Increased pressure/glaucoma equals cuppingof optic nerve- half has to be gone before any vision loss occurs effects peripheral vision first (tunnel vision)

40
Q

Common retinal disorders

A

Retinal detachment
Diabetic retinopathy
Macular degeneration -wet or dry peripheral vision normal but central vision lost

41
Q

How to test visual acuity

A

Measured at 6 metres
Described in angles to remove distance factor
6/24 means measured at 6 metres, able to read line 24 of snellen chart

42
Q

What makes up left visual field in the brain

A

Temporal hemi field in left eye (90 degrees)

Nasal hemi field in right eye (60 degrees)

43
Q

What makes up right visual field in the brain

A

Temporal hemi field in right eye

Nasal hemi field left eye

44
Q

Optic nerve in relation to macula

A

Optic nerve is always NASAL to macula

Blind spot is always temporal on visual field (if dark spot on the left then it is left eye)

45
Q

Pathology in both temporal hemi fields lost

A

Optic chiasm

Bitemporal hemiopia

46
Q

Pathology in left temporal hemi field and right nasal hemi field loss

A

Right side-posterior to optic chiasm

Left homonymous hemiopia

47
Q

Pathology in loss of superior part of both left temporal and right nasal

A

Right optic tract inferior and posterior to chiasm

Left superior homonymous quadratinopia

48
Q

Marcus Gunn pupil

A

Relative Afferent Pupillary Defect
Shine light in normal eye=both pupils constrict
Shine light in abnormal eye=both pupils dilate

49
Q

How to reveal a squint (strabismus) with cover up test

A

Convergent squint:
Normal eye covered, squinting eye moves outwards
Divergent squint:
Normal eye covered, squinting eye moves inwards

50
Q

How to reveal a squint (strabismus) with light reflection test

A

When shining a light 33cm away, reflexes should be symmetrical in both eyes
A reflex displaced outwards=convergent strabismus
A reflex displaced inwards= divergent squint

51
Q

5 different types of Ishihara plates (non-diagnostic)

A

Alternating-see different number if you are colour blind or not
Hidden-normal people see no number
Invisible-normal people see a number
Diagnostic-normal people see 2 numbers, colour blind see 1
Non-verbal plates

SS (11 decks)

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