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RR Y2 NEURO > Eye 1 > Flashcards

Eye 1 Flashcards

1
Q

Tears are produced by what

A

Lacrimal gland

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2
Q

Tears gather in

A

Tear sac

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3
Q

Tears exit through and reach

A

Tear duct and reach nasal cavity

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4
Q

Describe how tears drain

A

Tears drain through 2 puncta, openings on medial lid margin.

Tears flow through superior and inferior canaliculli

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5
Q

Tear film function

A

Maintains smooth cornea– air surface
O2 supply to cornea (as cornea has no blood vessels)
Removal of debris
Bactericide

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6
Q

3 layers of tear film

A

1) Superficial oily layer
2) Aqueous tear film
3) Mucinous layer on corneal surface to maintain surface wetting

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7
Q

Functions of each of the layers

A 
Superficial oily layer
-reduce tear film evaporation
Aq tear film
-Tear gland
Mucinous Layer
-On corneal surface to maintain surface wetting
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8
Q

Describe appearance Conjunctiva

A

Thin transparent tissue

Covers outer surface of eye
Covers visible part of eye and lies inside of eyelids
Nourished by tiny blood vessels

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9
Q

What is the average anterior-posterior diameter of the orbit?

A

24mm

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10
Q

Which bit of eye is responsible for 2/3rd of focusing power

A

Cornea

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11
Q

3 layers of eye?

A

Sclera
Choroid
Retina

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12
Q

Describe these layers

A

Sclera

  • Hard and opaque
  • High h2o cont
  • Protective outer coat

Choroid
-Pigmented and vascular

Retina
-Neurosensory tissue

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13
Q

Describe appearance of cornea

A
  • Transparent, dome shaped (convex)
  • Front of eye
  • Continuous w sclera
  • Low water content
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14
Q

Function of cornea

A

Powerful retracting surface
Physical barrier
Infection barrier

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15
Q

5 layers of cornea

A 
Epithelium
Bowman's membrane
Stroma
Descemet's membrane
Endothelium
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16
Q

Function of stroma

A

Regularity of stroma contributes towards transparency

Corneal nerve endings (cornea has no blood vessels)

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17
Q

Function of Endothelium

A

Pumps fluid out of endothelial cell
No regen power
Dysfunction may result in corneal oedema and corneal cloudiness

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18
Q

Appearance of cornea when hydrated

A

Turns white

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19
Q

Uvea function and location

A

Vascular coat of eyeball

Lies between sclera and retina

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20
Q

3 part of uvea

What happens when one part is diseased

A

Iris
Ciliary body
Choroid

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21
Q

Location of choroid

A

Between retina and sclera – part of uvea

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22
Q

Choroid composed of

A

Blood vessel layers that nourish back of eye

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23
Q

Part of eye that does’nt have blood vessels or nerves

A

Cornea

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24
Q

Part of eye with refactive power of remaining 2/3

A

Lens

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25
Q

Iris function

where

A

Controls light levels

Embedded w tiny muscles that dilate and constrict w pupil size

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26
Q

Lens appearance

A

Outer acellular capsule

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27
Q

Function of lens

A

Regulate inner elongated cell fibres – transparency

Refractive power

Accomodation-elasticity

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28
Q

Lens zonules appearance

-consists of?

A

lens suspended by fibrous ring

–> passive connective tissue

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29
Q

Retina
Structure
Function

A

Thin layer of tissue that lines inner part of eye

Capture light rays
Light impulses sent to brain for processing via optic nerve

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30
Q

Optic nerve

Function
Connects to eye near which structure
Visible part of optic nerve

A

Transmits nerve impulses from retina to brain

Connects to back of eye near macula

Optic disc

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31
Q

Structure in middle of retina, temporal to optic nerve

A

Macula

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32
Q

Function of macula

A

Small and highly sensitive part of retina responsible for detailed central vision

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33
Q

Fovea located where

A

Pit located at centre of macula

Macula located on retina, fovea located on macula

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34
Q

Anterior and posterior segments of eye separated by?

A

Lens

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35
Q

Anterior chamber
located where?
Contains?

A

Between cornea and lens

Filled w aq fluid – supplies nutrients

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36
Q

Ciliary body produces

A

Aq humour

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37
Q

Where is aq humour produced and where does it run into

A

Produced from ciliary bodies runs into anterior chamber
80% into canal of schlemm
20% into uveal scelal outflow

38
Q

Glaucoma
Progressive death of what cell
Loss of what tissue
What happens to visual field

A

associated with progressive retinal ganglion cell death,

loss of nerve fibres and visual field loss

39
Q

Glaucoma

A

Optic neuropathy w characteristic structural damage to the optic nerve, associated with progressive retinal ganglion cell death,
loss of nerve fibres and visual field loss

40
Q

Glaucoma

Features of concern

A

Raised intraocular pressure
Retinal gang cell death
Enlarged optic disc cupping

41
Q

2 types of glaucoma

A

Primary open angle glaucoma

Closed angle glaucoma

42
Q

Describe the 2 types and affect they have on trabecular meshwork

A

Primary open angle glaucoma

  • (Left) commonest
  • Trabecular meshwork dysfunction

Closed angle glaucoma

  • Can be acute or chronic
  • Increased pressure pushing the iris/lens complex forward.
  • Blocks the trabecular meshwork
43
Q

Risk factor of glaucoma

A

Small eyes-hypermetropia

-Narrow angle at trabecular meshwork

44
Q

How might someone with glaucoma present

A

Sudden painful red eye, w acute drop in vision

45
Q

How can glaucoma be treated

A

W peripheral laser irditomy to create a drainage hole on the iris

46
Q

Define optic nerve blindspot

A

Where optic nerve meets retina

-there are no light sensitive cells- blind spot

47
Q

Most sensitive part of retina and how

A

Fovea (centre of macula thats located on retina)
Highest conc of cones and low rods
– Peripheral vision

48
Q

Corresponding anatomic landmark for physiological blind spot

A

Optic disc

49
Q

Which type of vision is responsible day vision Vv

A

Central vision

night -Peripheral vision

50
Q

How can Central vision be assessed

A

Visual acuity assessment

51
Q

How can peripheral vision be assesssed

A

visual field assessment

52
Q

Central vision responsible for?

A

Colour vision fovea, reading, facial recognition

53
Q

Peripheral vision responsible for?

A

Shape, movement

54
Q

Retinal structure

3 layers and function

A 
Outer
-1st order neuron- detection of light
Middle 
-2nd order neuron- local signal processing to improve contrast sensitivity, regulate sensitivity  
Inner 
-Retinal ganglion cells
-3rd order neruon 
-Transmission of signal from eye to brain
55
Q

Approximately how many rods and cones

A

120 million rods

6 million cones

56
Q

Macula diameter

A

6mm

57
Q

How long does it take for cone to adapt

A

7 mins

58
Q

How long does it take for rod to adapt

A 
30 mins (more rods as well)
regeneration of rhodopsin
59
Q

Macula Lutea appearance

A

Yellow patch

60
Q

Macula in retina appearance

A

a pigmented region

61
Q

Why does fovea form a pit

A

Due to absence of overlying gang cell layer

62
Q

Which part of eye has highest conc of photoreceptors,what can it clinically be assess with

A

Fovea

OCT scan

63
Q

Where are photoreceptors located

A

In retina

Rod and cone

64
Q

Which photoreceptor is 100x more sensitive to light

A

Rod photoceptors

65
Q

What are their responses to light like

A

Slow

66
Q

What photoreceptors are responsible for night vision (scotopic)

A

Rod photoreceptors

67
Q

Where is the highest conc or rod photoreceptors

A

20-40 degrees away from fovea

68
Q

Test for colour perception

what colour deficiencies do they test for

A

Ishihara test

Green and red

69
Q

Dark adaption how many phases

A

biphasic

70
Q

Commonest form of colour vision deficiency in hujahs

A

Red green confusion

therefore ishihara test

71
Q

2 types of lens

A

Converging diverging lens

72
Q

Shape of converging and shape of diverging lens

function

A

Convex
Concave

Converging lens- take light rays and bring them to a point
Diverging lens-take light ray and spread outward

73
Q

what sits in the limbus

A

corneal stemcell

74
Q

Emmetropia

A

perfect focusing ability

75
Q

Ametropi

A

Category of condition where light rays don’t fall on retina

76
Q

Near sightedness

A

Myopia

77
Q

Farsightedness

A

Hyperopia

78
Q

Parallel rays converging at focal point posterior to retina leads to

A

Hyperopia

79
Q

Excessive short glove (axial hyperopia) can lead to

A

Hyperopia

80
Q

Insufferable refractive pwoer – refractive hyperopia lead to

A

Hyperopia

81
Q

Asthenopic symptoms

A

Eyepain, headachein fronal region– where eyes are, burning sensation in eyes,
blepharoconjunctivities –asthenopic symptoms- tired eyes

82
Q

Condition in which parallel rays come to focus in 2 focal lines rather than a single focal point

A

Astigmatism

83
Q

Response triad is an adaption for?

A

Near vision

84
Q

Near response triad consists of and function

A 
Pupillary Miosis (Sphincter
Pupillae) to increase depth
of field
– Convergence (medial recti
from both eyes) to align
both eyes towards a near
object
– Accommodation (Circular
Ciliary Muscle) to increase
the refractive power of
lens for near vision
85
Q

cause of astigmatism

A

Cause : refractive media is not spherical–>refract differently
along one meridian than along meridian perpendicular to it–
>2 focal points ( punctiform object is represent as 2 sharply
defined lines)

86
Q

Symptoms and treatment of astigmatism

A

Astigmatism
• Symptoms
– asthenopic symptoms ( headache , eyepain)
– blurred vision
– distortion of vision
– head tilting and turning
• Treatment
– Regular astigmatism :cylinder lenses with or
without spherical lenses(convex or concave), Sx
– Irregular astigmatism : rigid CL , surgery

87
Q

Presbyopia

A

• Naturally occurring loss
of accommodation
(focus for near objects)

age 40 upwards

long distance fine

reading glasses

88
Q

Accommodation Mechanism

A 
Contraction of the Circular
Ciliary Muscle inside the
Ciliary Body
– This relaxes the zonulesthat
are normally stretched
between the ciliary body
attachment and the lens
capsule attachment
– Note that zonules are passive
elastic bands with no active
contractile muscle
– In the absence of zonular
tension, the lens returns to
its natural convex shape due
to its innate elasticity
– This increases the refractive
power of the lens
• Mediated by the efferent
Third Cranial Nerve
89
Q

Accomodation is mediated by which cranial nerve?

A

3rd

90
Q 
• In accommodation,
which one of the
following events does
not take place?
– A) Relaxation of Circular
Ciliary Muscle
– B) Relaxation of Zonules
– C) Thickening of Lens
– D) Increase of Lens
Refractive Power
A

– A) Relaxation of Circular

Ciliary Muscle

91
Q

Intracollamer lens (ICL) can be used for which conditions

A

Astigmatism and myopia

RR Y2 NEURO (24 decks)

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