The Eye Flashcards
1
Q
Basal corneal epithelial cells are anchored to Bowman layer by?
A
Hemidesmosomes
2
Q
Limbus houses _____ ____ ___ and _______ which link schlemm canal to aqueous veins
A
corneal stem cells
collector channels
3
Q
The sclera is vascualr or avascular?
A
Avascular
4
Q
What overlies the sclera
A
Episclera - 2 vascular layesr deep and superficial
5
Q
The retina has dual circulation - what is it
A
Inner retina by reintal vessles
Outer retina by choroid
6
Q
Radius of cornea
A
8mm
7
Q
Radium of sclera
A
12mm
8
Q
Which is greater in the globe? the equatorial or polar radius
A
equatorial
9
Q
What is the anteroposterior diameter of the adult eye
A
23-25mm
10
Q
Transverse diameter of adult eye
A
24mm
11
Q
Average ACD
A
3.11mm
12
Q
Average volume of anterior chamber
A
220 uL
13
Q
Posterior chamber colume
A
60uL
14
Q
Total volume of adult eye
A
6.5-7ml
15
Q
Volume of vitreous gel
A
5-6ml
16
Q
Grossly what are the 3 layers ofthe globe
A
outer protective layer middle vascular inner neural layer
17
Q
Uvea is made up of
A
Choroid, Ciliary body, iris
18
Q
What are the 3 layers of the precorneal tear film
A
Lipid
Aqoud
Mucin
19
Q
Lipid layer of pre corneal tear film produced by?
A
Meibomian gland
20
Q
Aqueous layer of pre corneal tear film produced by?
A
Lacrimal gland
21
Q
Mucin layer of pre corneal tear film produced by?
A
goblet cells
22
Q
What mediates the interaction of the mucoaqueous layer with the surface epithelial cells of the corena
A
Glycocalyx
23
Q
Is the cornea vascular or avascualr
A
Avascualr
24
Q
What are the 5 layers of the cornea
A
Epithelium
Bowman Layer
Stroma
Descemet
Endothelium
25
Cornea radius of curvature
7.8mm
26
Cornea refractive index
1/376
27
Dioptre power of cornea
43.25
28
Total refractive power of eye
58.60
29
Cornea derives nutrients from?
Aqueous humour
30
Horiszontal diameter of cornea
12mm
31
Vertical diameter of cornea
11mm
32
Which is more curved - posterior or anterior surface of the cornea
Posterior
33
Where is the cornea thinnest
centrally
34
Where is cornea flatter
in the periphery
35
Anterior surface of corena is covered by _________ ____ ______ epithelium
Non keratinized
stratified
squamous
36
How many cells layers is the nonkeratinized stratified squamous epitherlium
4-6layers
37
How thick is the non keratnized stratifies squamous epithelium
40-50 micormeter
38
Corneal surface epithelial cells are attached by?
Tight junctions
39
After injury is Bowman's layer restored
No forms scar tissues
40
After injury is Descemet layer restored
Yes
41
Corneal stroma is _% of total corneal thickness
90%
42
THe stroma is composed of ______-_____ _____, ground substance and ______ ______
collagen producing keratocytes
collaged lamellae
43
Ground substance is made up of ?
Proteoglycans
44
What is the basal lamina of the corneal endothelium
Descemet membrane
45
What is Descement membrane thickness at birth and adulthood
birth 3-4um
10-12um
46
Descemet membrane is rich in Type _ collagen
Type IV
47
Peropheral excresecences of Descemets membrane is known as
Hassal Henle Warts
48
Central excresxcences of Descemets membrane is known as
corneal guttae
49
Corneal endothelium os composed of ______ layer of _____ cells
single layer of hexagonal cells
50
HExagonal cells of the corneal endothelium are derived from
neural crest
51
Adult density of corneal endothelial cells is
3000mm2
52
Specular microscopy is used to visualise
Endothelial cells - size shape distribution
53
The transition zone between the peripheral cornea and anterior sclera is known as the
limbus
54
Limbal palisades of Vogt house the ?
corneal stem cells
55
Schwalbe line is the termination of
Descemet membrane
56
Where is the sclera thinnest?
Behind insertions of the rectus muscles
57
Where is the sclera thickest?
Posterior pole around optic nerve head
58
Most common site of scleral rupture following blunt trauma
Supernasal quad near limbus
circumferential arc parallel to corneal limbus opposte site of impact
behind the insertion of rectus muscles
59
Endothelial cells in schlemm canal are joined by?
tight junctions
60
Lens contributes __D of 60D to eyes focusing power
20S
61
equatorial diameter of lens at birth
6.5mm
62
Equatorial diameter of lens in adult
9-10mm
63
AP width of lens at birth
3mm
64
AP width of lens in adulthood
6mm
65
accomadation is acheived by ______ contraction
ciliary muscle
66
Lens capsule rich in Type _ collagen
Type IV
67
Pedicle
Cone
68
Spherule
Rod
69
How many rods in the retina
100-125 millin
70
How many cones in the retina
6-7 million
71
Which layer of retinal are muller cells nuclei locates
inner nuclear layer
72
What type od cells are Muller cells
Glial cells
73
What is the role of glial cells in the retina
Structural support and nutrition
74
main type of collagen in vitreous
type 2
75
What is the venous drainage of the conj
super and inf ophthalmic veins
76
refractive index of cornea
1.376
77
what is the total refractive power of the cornea
43
78
50% of stroma is _____ collagen
type 1
79
Descemet's is mainly type __ collagen
type IV
80
where is glucose supply to corneal epithelium from?
tear film
81
where is glucose supply to corneal endothelium from?
aqueous
82
Main way glucose is metabolised in the cornea
anaerobic glycolysis
83
what is the most common corneal proteoglycan
keratan sulphate
84
does pupillary dilatation increase or reduce diffraction
reduce
85
does pupillary dilatation increase or reduce chromatic abberation
increase
86
light entering at the edge of the pupil is less effective at stimulating photreceptors than light entering centrally because it meets the receptors obliquely rather than head on is called
Stiles-Crawford effect
87
Pupil dilatation increases or reduces the Stiles Crawford effect
increases
88
Mydrisasis is caused by contraction of
dilator pupillae
89
Mydriasis is stimulated by __________ _____ nerves passing through ciliary ganglion
Noradrenergic sympathetic
90
Miosis is stimulated by contraction of
sphincter pupillae
91
Miosis is stimulated by ________ postganglionic ______ fibres from the ciliary ganglion
chloinergic parasympatheitc
92
In Horner's pupil, will cocaine dilate the pupil
No, increased adrenergic activity by preventing reuptake has no effect on interrupted neural pathway
93
Hydroxyamphetamine will dilate a _____ and ____ neruone Horner but not a _____ order neurone lesion
Hydroxyamphetamine will dilate a 1st and 2nd neruone Horner but not a 3rdorder neurone lesion
94
The lens has greater curvature ______
anteriorly
95
lens diameter
10mm
96
Lens placode develops from surface ectoderm at what day
27 days
97
Lens placode invaginates into optic cup to from lens vesicle at day
33
98
anterior lens suture is ___ shaped
Y
99
posterior lens suture is _____ shaped
inverted Y
100
Aquaporin-0 functions as a ?
water channel
101
in the lens sodium is low/high and potassium is low/high
sodium low and potassium high
102
most important antioxidant in the lens
glutathione
103
choroid has high/low flow and high/low oxygen excahnge
high flow low exchange
104
choroidal vessels are embedde in type __ collagen matrix
III
105
what are the 3 vessel layers in the choroid called
choriocappilaris and Hallers and Sattlers
106
which layer in the choroid has larger vessel forms
Hallers layer
107
Lamina vitrea also called____ _______
Bruchs membrane
108
what are the 5 layers of lamina vitrea
RPE, collagen, elastic, collagen, choriocappilaris
109
choriocapillaris is most dense and widest where in the retina
macula
110
choriocapillaris receives blood from which layer
sattler's layer
111
less/more laserp power required for photocoagulation of darkly pigemented fundu
less
112
main type of collagen in the vitreous
type II
