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Neurology Y2 > L16 - Diseases of the eye > Flashcards

L16 - Diseases of the eye Flashcards

1
Q

Describe the role of the Iris ?

A
  • Regulates amount of light that enters eye.
  • Forms coloured, visible part of eye in front of lens.
  • Light enters through central opening called the pupil.
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2
Q

What layers can the eyeball be divided into? (3)

A
  1. Fibrous
  2. Vascular
  3. Inner layers
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3
Q

Describe fibrous layer of the eye?

A

Outermost.

Consists of Sclera and cornea (continuous with each other)

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4
Q

Describe the Sclera? (4)

A
  • Comprises majority of the fibrous layer.
  • Provides attachment to extraoccular muscles.
  • Not transparent.
  • White part of eye.
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5
Q

Describe cornea?

A
  • Transparent
  • positioned centrally at front of eye.
  • No BV.
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6
Q

What does the vascular layer of the eye consist of? (3)

A
  1. Choroid
  2. Ciliary body
  3. Iris
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7
Q

Describe the Choroid?

A
  • Layer of connective tissue and BV.

- Provides nourishment to outer layers of retina.

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8
Q

Describe the Ciliary body?

A

2 parts:

  • ciliary muscle
  • ciliary processes

a. Attached to lens of eye.
b. Controls shape of lens.
c. Contributes to formation of aqueous humor.

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9
Q

Describe the Iris?

A

Circular structure with aperture in the centre (the pupil).

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10
Q

Describe the inner layer of the eye?

A
  1. Retina (light detecting part)
    - Neural layer
  2. Inner most, photoreceptors.
    - Pigmented layer

Attached to choroid layer.

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11
Q

Where is the lens located?

A

located anteriorly between vitreous humor and pupil.

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12
Q

Describe the anterior and posterior chambers of eye?

A

Filled with aqueous humor.

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13
Q

Describe the production of aqueous humor? (4)

A
  1. Produced at Ciliary processes
  2. Flows from post. chamber —> pupil —> ant. chamber
  3. Flows out through trabecular meshwork into Schlemm’s canal.
  4. Subsequently absorbed into episceral veins via collector channels.
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14
Q

Where is aqueous humor secreted from?

A

Ciliary epithelium lining ciliary processes.

Enters the post. chamber.

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15
Q

What are zonules?

A
  • Fibrous strands

- connect ciliary body with crystalline lens of eye.

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16
Q

Briefly state a cause of glaucoma?

A
  • If drainage of aqueous humor obstructed

- can result in glaucoma.

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17
Q

What is intraocular pressure?

A

Fluid pressure inside eye.

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18
Q

What determines intraocular pressure?

A
  • Production and drainage of aqueous humour
  • by the ciliary body
  • and its drainage via the trabecular meshwork and uveoscleral outflow.
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19
Q

How would you measure intraocular pressure?

A

Tonometer.

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20
Q

What are the seven extraocular muscles?

A
  • levator palpebrae superioris
  • superior rectus
  • inferior rectus
  • medial rectus
  • lateral rectus
  • inferior oblique
  • superior oblique
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21
Q

Which muscles are responsible for eye movement?

A
  1. Recti
    sup, inf, medial, lateral
  2. Oblique
    inf
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22
Q

Which is the only muscle involved in raising the superior eyelid?

A

Levator palpebrae superioris

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23
Q

What is the attachment, action and innervation of levator palpebrae superioris?

A
  • Originates from lesser wing of sphenoid bone.
  • Attaches to superior tarsal plate of upper eyelid.
  • Elevates upper eyelid.
  • CN III, oculomotor.
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24
Q

Describe the superior tarsal muscle?

A
  • Collection of smooth muscle fibres, small portion of Levator Palpabrae Superioris.
  • Innervated by sympathetic nervous system.
25
Q

Where do the four recti muscles originate from?

A
  • Common tendinous ring.

- Fibrous ring of tissue surrounding optic canal at back of orbit.

26
Q

Superior rectus

  • attachment
  • actions
  • innervation
A
  • Originates from sup part of common tendinous ring.

Attached to sup. ant. aspect of sclera.

  • ELEVATION.
    contributes to adduction and medial rotation of eye.
  • CN III
27
Q

Inf. Rectus

  • attachment
  • actions
  • innervation
A
  • Orig from inf. part of common tendinous ring.
    attached to inf. ant. aspect of sclera.
  • DEPRESSION.
    also has role in adduction and lateral rotation of eye.
  • Innervation via CN III
28
Q

Medial Rectus

  • attachments
  • actions
  • innervation
A
  • Orig from medial part of common tendinous ring.
  • attaches to anteromedial aspect of sclera.
  • ADDUCTS eyeball
  • Innervation via CN III
29
Q

Lateral rectus

  • attachment
  • actions
  • innervation
A
  • Origin: lateral part of common tendinous ring.
  • attaches to anterolateral aspect of sclera
  • ABDUCTS eyeball
  • Innervation via Abducens nerve CN VI.
30
Q

Where do oblique muscles attach too?

A

Posterior surface of the sclera.

31
Q

Superior oblique

  • attachment
  • actions
  • innervation
A
  • origin: body of sphenoid bone.
  • tendon passes through trochlear and then attaches to sclera of eye. posterior to surface of sclera.
  • DEPRESS, ABDUCT, MEDIALLY ROTATES
  • Innervation via Trochlear CN IV
32
Q

Inferior oblique

  • attachment
  • actions
  • innervation
A
  • Originates from ant aspect of orbital floor. attaches to sclera of eye, posterior to lateral rectus.
  • ELEVATES, ABDUCTS AND LATERALLY ROTATES EYEBALL
  • Innervation via oculomotor nerve CN III
33
Q

Lesion in Oculomotor nerve may result in?

A
  • Most of extraocular muscles affected.
  • Eye displaced laterally by lateral rectus and inferiorly by sup oblique.
  • Eye adopts ‘down and out’ position
34
Q

Lesion in Trochlear nerve may result in?

A
  • Paralyse superior oblqiue muscles.
  • Patient will complain of diplopia (double vision)
  • May develop a head tilt away from site of lesion.
35
Q

Lesion is Abducens nerve may result in?

A

Paralyse lateral rectus.

Affected eye will adduct by resting tone of the medial rectus.

36
Q

What are the triad of symptoms involved in Horner’s syndrome where there is damage to the neck?

A
  1. Partial ptosis
  2. Miosis
  3. Anhydrosis
37
Q

Describe partial ptosis

A

Drooping of upper eyelid

- Result of denervation of superior tarsal muscle

38
Q

Describe Miosis

A

Pupillary constriction

- due to denervation of dilator pupillae muscle

39
Q

Describe anhydrosis

A

Absence of sweating
Ipsilateral side of face
- due to denervation of sweat glands

40
Q

Clinical revelance of Glaucoma

A

Group of eye diseases that result in damage to optic nerve

  1. Open angle
    - outflow of aqu.hum. through tracbecular meshwork is reduced.
    - gradual reduction in peripheral vision.
  2. Closed angle
    - iris forced against trabecular meshwork, prevents drainage of aqu.hum.
    - can rapidly lead to blindess
41
Q

What is a refractive error?

A

Occurs when shape of eye prevents light from focusing directly on retina.

42
Q

What is myopia?

A

Nearsightedness

  • objects near are clear
  • objects further away are blurry
43
Q

What is hyperopia?

A

Farsightedness

- distant objects clearer

44
Q

What is astigmatism?

A

Type of refractive error caused by irregularities in patients cornea shape.
- cornea rugby ball shaped instead of football

45
Q

What is presbyopia?

A

Long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and long age.

46
Q

What is keratoconus?

A

Non-inflammatory eye condition

Cornea progressively thins causing a cone-like bulge to appear.
- impairs ability of eye to focus light properly.

47
Q

Describe a normal cornea?

A

Round dome-shaped clear window of eye.

48
Q

What is cataracts?

A

Clouding of lens inside eye.

49
Q

How may cataracts form?

A

As we age:

  1. lens in eyes becomes less flexible
  2. less transparent
  3. thicker.
  • tissues within lens break down and clump together
  • which clouds small areas within lens
50
Q

What is Age-related macular degeneration?

A
  • Occurs when macula (central bit of retina) deteriorates

- Affects middle part of vision but not edges.

51
Q

How may diabetes lead to loss of vision?

A

Diabetes can lead to swelling in the Macula
- diabetic macular edema.
Overtime this disease can destroy the sharp vision in that part of the eye.

52
Q

Describe retinal vascular disorders?

A

Range of eye diseases that affect the BV in eye.

53
Q

Describe retinal detachment?

A

Retina separates from back of inside of eye.

  • preceded by posterior vitreous detachment
  • gives rise to —> brief flashes of light (photopsia) in extreme peripheral vision.
54
Q

Describe refractive errors in children?

A

examples: myopia, hyperopia and astigmatism

- caused blurred vision due to inability to focus images on retina.

55
Q

Describe strabismus?

A

Cross-eyed
Children with strabismus initially have double vision - occurs due to the misalignment of two eyes in relation to one another.

56
Q

What is leucoma?

A

White opacity in the cornea of the eye.

57
Q

What is retinitis pigmentosa?

A

Genetic disorder of eyes causing loss of vision.

Symptoms: trouble seeing at night and decreased peripheral vision.

58
Q

What is the underlying mechanism of retinitis pigmentosa?

A

Progressive loss of rod photoreceptor cells in the back of the eye.
- followed by loss of cone photoreceptor cells.

Neurology Y2 (24 decks)

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