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Neuro > Structure & Function of Eye - Part 1 > Flashcards

Structure & Function of Eye - Part 1 Flashcards

1
Q

Three types of tears

A

Basal tears
Emotional tears
Reflex tears

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2
Q

What is the afferent pathway for reflex tear production?

A

Opthalmic branch of trigeminal nerve (V1)

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3
Q

What is the efferent pathway for reflex tear production?

A

PNS

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4
Q

What are the three layers of basal tears?

A 
Superficial lipid layer 
Aqueous layer (tear film)
Mucin layer (continuous with cornea)
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5
Q

What produces the superficial layer of tears and what is this layer’s function?

A

Meibomian glands produce oily layer, which prevents evaporation of tears

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6
Q

What produces the tear film?

A

Tear glands

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7
Q

List four functions of the tear film

A

Bactericide
Debris removal
Oxygen supply to cornea
Maintenance of smooth cornea-air surface

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8
Q

Which structure covers the cornea?

A

Conjunctiva

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9
Q

Describe how the conjunctiva is distributed

A

Begins at outer edge of cornea
Covers eye
Lines inside of eyelid

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10
Q

Describe the properties of conjunctiva

A

Transparent tissue

Nourished by nearly invisible blood vessels

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11
Q

Describe the outermost structure of the posterior segment of the eye

A

Sclera

  • opaque
  • maintains eye shape
  • tough
  • high water content
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12
Q

Describe the properties and function of the choroid

A

Vascular
Pigmented
Provides circulation
Shields unwanted scattered light

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13
Q

Describe the properties and function of the retina

A

Neurosensory

Translates light into neural impulses

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14
Q

Describe the flow of tears

A 
Produced by lacrimal gland 
Covers eye 
Drains into punctum 
Travels via superior and inferior canaliculi into:
Tear sac
Tear duct 
Nose
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15
Q

What is continuous with the sclera?

A

Cornea

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16
Q

Describe the properties of the cornea

A 
Transparent 
Convex
Does 2/3 of refraction (higher refractory index than air)
Physical barrier 
Infection barrier
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17
Q

State the five layers of the cornea

A 
Epithelium 
Bowman's membrane 
Stroma 
Descemet's membrane 
Endothelium

(Every blue sky deserves notice)

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18
Q

Which layer of the cornea provides nutrients to the other layers and how?

A

Stroma - nerve endings provide nutrients as there is no blood supply in the cornea

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19
Q

Describe the function of the endothelium in the cornea

A

It pumps fluid out of cornea, preventing cerebral oedema

20
Q

What may result from endothelial cell dysfunction?

A

Corneal oedema

Corneal cloudiness

21
Q

Describe some properties of the endothelium

A

1 cell thick

No regeneration power

22
Q

What is the uvea and what three things is it composed of?

A

Vascular coat of eye between sclera and retina, composed of:

Iris
Ciliary body
Choroid

23
Q

Which part of the eye has a similar function to controlling the aperture on a camera? Describe the function of this structure.

A

IRIS - controls light levels

24
Q

What two muscles make up the iris and what are their functions?

A

Sphincter pupilae (Circular muscle): Constricts pupil

Dilator pupilae (raDIAL muscle) - DILAtes pupil

25
Q

Describe the structure of the lens including its outer and inner layers

A

Outer acellular layer
Inner layer of elongated cell fibres

Biconvex

26
Q

What is the lens made of which gives it its transparency?

A

Transparent collagen

27
Q

What is the significance of having elongated cell fibres?

A

Enables elasticity for accommodation

28
Q

Which action fattens the lens?

A

Contraction of ciliary muscles PUSHES the lens zonules, making the lens fatter

29
Q

Which action flattens the lens?

A

Relaxation of ciliary muscles PULLS the lens zonules, making the lens flatter

30
Q

What refractory power does the lens have?

A

1/3

the other 2/3 is provided by the cornea

31
Q

What is the optic disc?

A

The visual portion of the optic nerve

32
Q

Where does the optic nerve connect to?

A

Near the macula

33
Q

What is the macula?

A

The middle of the retina, responsible for detailed central vision

34
Q

What is the fovea

A

The central part of the macula which enables detailed vision

35
Q

Describe the difference in fluid composition in the two segments of the eye

A

Anterior segment - aqueous humour

Posterior segment - vitreous humour

36
Q

What forms the axis by which the segments are divided in the eye?

A

Lens

Anterior segment is anterior to the lens (between cornea and lens)

Posterior segment is behind lens

37
Q

What are the two outflows of aqueous humour? Which of these is passive?

A

Trabecular meshwork-canal of Schlemm (90%)

Uvea-scleral flow (10%) - passive

38
Q

Describe the flow of aqueous humour

A 
Produced by ciliary body 
Flows anteriorly into anterior chamber 
Supplies nutrients
Drains via trabecular meshwork 
Into canal of Schlemm
39
Q

What is the consequence of having a raised IOP in glaucoma?

A

Death of retinal ganglion cells; visual field loss; blindness

40
Q

What can be seen in the retina of someone with glaucoma?

A

Enlarged optic disc ‘cupping’ as a result of damage to the optic nerve

41
Q

State the two types of glaucoma. Which of these is more common?

A 
Open angle (most common)
Closed angle
42
Q

What causes open angle glaucoma?

A

Trabecular meshwork dysfunction

43
Q

What causes closed angle glaucoma?

A

Increased IOP pushes lens and iris forwards, blocking the trabecular meshwork

44
Q

How might closed angle glaucoma present?

A

Sudden painful red eye with acute drop in vision (normally their mind fills in the image even if they can’t see)

45
Q

What are the risk factors of CAG?

A

Hypermetropia (small eye)

Pre-existing narrow angle at TM

46
Q

How is closed angle glaucoma treated?

A

Peripheral laser iridotomy (drainage hole in iris)

Neuro (11 decks)

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