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Fourth Year > Ophthalmology > Flashcards

Ophthalmology Flashcards

1
Q

The space between the eyelids is the?

(The orbicularis oculi is arranged as a ring of fibres around this).

A

Palpebral aperture or fissure.

(contraction of orbicularis oculi causes the eyelids to close).

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2
Q

Opening of the eyelids is primarily performed by?

A

Levator muscle of the upper lid.

(Tenuous fibres in the lower lid also retract lower lid).

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3
Q

The levator muscle of the eye extends from where?

A

an attachment at the orbital apex to the tarsal plate and skin (forms eye crease).

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4
Q

Eyelids are securely attached at either end to the bony orbital margin by?

A

The medial and lateral palpebral (or canthal) ligaments.

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5
Q

Trauma to the medial palpebral/ canthal ligament causes what?

A

Eyelid to move anteriorly and laterally.

Impairs both function and cosmesis.

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6
Q

What nerve(s) is associated with the afferent limb of the blink reflex?

A
  • Optic nerve.
  • Trigeminal nerve (CN V).
  • Auditory nerve.
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7
Q

What nerve(s) is associated with the efferent limb of the blink reflex?

A
  • Facial nerve.
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8
Q

What is the posterior lamella of the eyelids composed of?

A
  • Conjunctiva.

- Semi-rigid tarsal plate.

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9
Q

What is the anterior lamella of the eyelids composed of?

A
  • Skin.

- Orbicularis oculi.

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10
Q

Meibomian glands produce which component of the tear film?

A

Oily lipid component.

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11
Q

Sensory innervation of the upper lid is supplied via what nerve?

A

Ophthalmic division of the trigeminal.

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12
Q

Sensory innervation of the lower lid is supplied via what nerve?

A

Maxillary division of the trigeminal.

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13
Q

Orbicularis oculi receives innervation via?

A

Facial nerve (CN VII).

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14
Q

Levator muscle of the upper lid is supplied by which nerve?

A

Oculumotor nerve (CN III).

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15
Q

Which examination finding of the lids would suggest facial nerve palsy?

A

Ectropion of the lower lid, but NOT ptosis.

(palsy of CN III WOULD cause a ptosis).

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16
Q

Palsy of which nerve would cause a ptosis?

A

CN III - oculomotor.

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17
Q

Eyelid arterial supply via the face comes from which artery?

A

External carotid artery.

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18
Q

Eyelid arterial supply via the orbit comes from which artery?

A

Internal carotid artery.

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19
Q

Lymphatic fluid from the eyes drains into which groups of nodes?

A
  • Pre-auricular.

- Submandibular.

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20
Q

what are the two layers of the conjunctiva?

A
  • Epithelium.

- Stroma (posterior).

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21
Q

Describe the epithelium of the conjunctiva.

A

Contains goblet cells which secrete the mucin component of the tear film.

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22
Q

Sensory innervation of the conjunctiva is supplied via what nerve?

A

Ophthalmic division of trigeminal.

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23
Q

What is the name given to the area where the cornea and sclera merge?

A

The limbus ( at the corneal edge).

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24
Q

Name the layers of the cornea.

A
  1. Epithelium.
  2. Stroma.
  3. Endothelium.
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25
Q

The cornea is avascular. True or false?

A

True.

It derives its nutrition by diffusion from blood vessels at the limbus, aqueous humour and the tear film.

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26
Q

The cornea is innervated by?

A

Ophthalmic division of trigeminal.

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27
Q

Main functions of the cornea.

A
  • Protection against micro-organisms.

- Transmission and focusing of light.

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28
Q

What secretes most of the aqueous component of the tear film?

A

lacrimal gland.

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29
Q

The lacrimal gland is innervated by?

A

Parasympathetic fibres carried by the facial nerve.

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30
Q

The uvea is composed of?

A

Iris, ciliary body (anteriorly) and choroid (posteriorly).

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31
Q

What lines the posterior surface of the iris?

A

Pigment cells.

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32
Q

Main functions of the iris?

A
  • Control light entry to retina.

- Reduce intraocular light scatter.

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33
Q

Describe the mechanism behind pupil dilation.

A

Contraction of radial smooth muscle due to sympathetic innervation.

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34
Q

Describe the mechanism behind pupil constriction.

A

Contraction of the sphincter pupillae muscle (ring of smooth muscle around pupil) due to parasympathetic innervation (CN III).

35
Q

Which part of the ciliary body is the site in which aqueous humour is formed?

A

Ciliary processes.

36
Q

What happens when muscle fibres within the ciliary body contract?

A

ACCOMODATION (near vision) - Reduced tension on zonules > lens becomes more convex.

37
Q

Accommodation is due to innervation by which nerve?

A

Parasympathetics of oculomotor nerve.

38
Q

What shape should the lens be in distance vision?

A

Flat.

near - convex / round.

39
Q

The choroid is composed of?

A

Blood vessels, connective tissue and pigment cells.

40
Q

Where is the choroid located?

A

Between sclera and retina.

41
Q

What is the function of the choroid?

A

Provide oxygen and nutrition to outer retinal layers.

42
Q

What is presbyopia?

A

Failure of accommodation associated with ageing.

43
Q

How does presbyopia occur?

A

Loss of capsule elasticity and lens deformability.

44
Q

Where is the anterior chamber located?

A

Space between cornea and iris.

45
Q

Where is the posterior chamber located?

A

Space posterior to the iris and anterior to the lens.

46
Q

What fills the posterior and anterior chambers?

A

Aqueous humour.

47
Q

Neural control of aqueous humour formation is via?

A

Sympathetic autonomic nervous system (beta receptors).

48
Q

Describe the pathway of aqueous humour circulation.

A

Produced in ciliary body in posterior chamber > pupil > anterior chamber > trabecular meshwork > Schlemm’s canal > veins.

49
Q

Where is Schlemm’s canal located?

A

Corneoscleral limbus.

50
Q

Describe the trabecular meshwork of the eye.

A

Specialised tissue in anterior chamber (between iris and cornea).

51
Q

What is the vitreous body composed of?

A
  • 99% water, collagen fibrils, hyaluronan.
52
Q

Where is the vitreous particularly adherent to the retina?

A

Optic disc and ora serrata.

53
Q

What is the ora serrata?

A

Junction between retina and ciliary body.

54
Q

How does vitreous deterioration cause retinal detachment?

A

Vitreous body attached to retina, particularly at optic disc and ora serrata. Degeneration causes it to pull on the retina, causing it to tear and detach.

55
Q

function of the retina.

A

Converts focused light images into nerve impulses.

56
Q

What is the retina composed of?

A
  • Neurosensory retina.

- Retinal pigment epithelium.

57
Q

Which area of the retina provides for central vision?

A

Macula.

The rest is for peripheral vision.

58
Q

Fovea function?

A

Sharp central, high quality vision.

59
Q

What is concentrated at the macula and why?

A

Cones (photoreceptors) for visual acuity i.e. vision in bright light and colour appreciation.

60
Q

Rods are distributed throughout the entire retina (mostly peripheral), why?

A

Vision in low light levels and detection of movement.

61
Q

Blood is supplied to the retina from?

A

Central retinal artery and vein.

Choroid.

62
Q

What passes through superior orbital fissure?

A
  • Lacrimal, frontal and nasociliary nerves (ophthalmic division of CN V).
  • CN III, IV, VI.
  • Superior ophthalmic vein (passing to cavernous sinus).
63
Q

What passes through inferior orbital fissure?

A
  • Exiting inferior ophthalmic vein.

- Maxillary division of CN V.

64
Q

Compression at the orbital apex may result in what signs?

A
  • Loss of corneal sensation.
  • Reduced ocular movement.
  • Impaired visual function.
  • Proptosis.
65
Q

How may pupil dilation be achieved?

A
  • Anti-cholinergics - Tropicamide (2 hours), Cyclopentolate.
  • Sympathetic agonist - Phenylephrine.
  • Atropine (1 week).
66
Q

Pituitary tumour causes what visual field defects?

A

Bitemporal hemianopia.

67
Q

A unilateral lesion posterior to the optic chiasm would cause what visual field defect?

A

Hemianopia on contralateral side.

68
Q

Occlusion of the arterial supply to the visual cortex would cause what visual field defect?

A

Bilateral field loss with macular sparing (i.e. only central vision retained).

69
Q

What is visual acuity?

A

The measure of the ability of the eye to see that two close objects are in fact separate.

70
Q

Visual acuity is tested using?

A

Snellen chart.

71
Q

Colour appreciation is tested using?

A

Ishihara colour plates.

72
Q

Fluorescein mixes with the tear film, adhering to what?

A

Areas of epithelial loss (ulcer or abrasion).

73
Q

Fluorescein is best visualised using what colour of light?

A

Blue.

74
Q

How is unilateral optic nerve pathology (i.e. relative afferent pupil defect) tested?

A

Swinging flashlight test.

75
Q

What is the main cause of diminished red reflex?

A

Cataract.

76
Q

Monocular abnormal visual fields suggests?

A

Optic nerve or retinal pathology.

77
Q

Binocular abnormal visual fields suggests?

A

Intracranial disease.

78
Q

What is the role of the aqueous layer of the tear film?

A
  1. Smooths optical interface.
  2. Washes away debris.
  3. Conveys oxygen and antibacterials to corneal and conjunctival surfaces.
79
Q

What is responsible for secreting approximately 95% of the aqueous component of the tear film?

A

Main lacrimal gland.

+ additional secretion by accessory glands in conjunctiva

80
Q

Inner mucinous layer of tear film is produced mainly by?

A

Conjunctival goblet cells.

81
Q

What is the role of the inner mucinous layer of the tear film?

A

Provides a hydrophilic attachment for the aqueous component.

82
Q

Uveitis is associated with which systemic conditions?

A
  • Inflammatory bowel disease.
  • Sarcoidosis.
  • Seronegative arthritis (psoriatic, rheumatoid, reiter’s syndrome).
  • Ankylosing spondylitis.
  • SLE.
  • TB, syphilis, toxoplasmosis, Herpes (zoster and simplex)
  • etc etc
83
Q

Symptoms and signs of uveitis?

A
  • Painful red eye.
  • Photophobia.
  • Intraocular inflammation e.g. cells in anterior chamber.
84
Q

What is episcleritis?

A

Inflammation between conjunctiva and sclera.

  • Usually affects young, women.

Fourth Year (28 decks)

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