Block10 Flashcards
(173 cards)
1
Q
The pupil that is seen is actually a
A
Magnified virtual image of the real object pupil
2
Q
Separates AC and PC
A
Iris
3
Q
How much is the iris magnified by when viewed through the cornea
A
1/8th
4
Q
Average iris diameter
A
12 mm
5
Q
Thinnest point of the iris is
A
At the iris root - 500 microns
6
Q
Where is normal pupil center
A
Slightly inferionasal
7
Q
Abnormal decentered pupil
A
Ectopic
8
Q
Which area of the iris is broader in humans
A
Temporal iris
9
Q
Largest eyes in animal kingdom
A
Giant squid
10
Q
Largest eyes relative to body size
A
Tarsier
11
Q
Posterior iris is derived from
A
Neuroepithelium
12
Q
What structures of the iris are derived from neuroepithlium
A
Dilator muscle
Sphincter muscle
Posterior pigmented epithelium
13
Q
Anterior portion of the iris is derived from
A
Mesoderm
14
Q
What iris structures are derived from mesoderm
A
Stroma
Vessels
Nerves
Chromatophores
15
Q
4 layers of the iris (anterior to posterior)
A
Anterior border layer
Stroma
Anterior epithelium and dilator muscle
Posterior pigmented epithelium
16
Q
Which layer contains both mesoderm and ectoderm
A
Stroma and sphincter muscle
17
Q
3 main functions of the pupil
A
Control of retinal illumination
Reduction in optical aberrations
Depth of focus
18
Q
Functions of the iris (6)
A
Regulate retinal illumation Regulate glare Regulates optical aberrations Regulates depth of focus Provides nonverbal communication and social signaling Attraction/mate selection
19
Q
Pupillary portion of iris gathers into pleats while ciliary portion smooths out: miosis or mydriasis
A
Miosis
20
Q
Stromal pulls flat while contraction furrow appear in ciliary area: miosis or mydriasis
A
Mydriasis
21
Q
Thickest portion of iris
A
Stroma
22
Q
Function of stroma
A
Anchor for
- sphincter muscle
- dilator-posterior-epithelial plate
- iris nerves
- iris vessels
23
Q
Is the iris considered porous
A
Yes
24
Q
Newborns typically have what colored iris? Can it change?
A
Blue; yes
25
What causes iris to change colors
Development of anterior stromal melanocytes and production of pigment granules
26
What colored iris are more dominant
Darker colors
27
Blood flow to iris is derived from
Ophthalmic artery and 2 long posterior ciliary arteries and anterior ciliary arteries
28
Anterior ciliary arteries run along
Recti muscles
29
How many anterior ciliary arteries run along each recti muscle
2, except LR only has 1
30
Unique to the iris vessels and found nowhere else in the body
Perivascular collagen sheaths
31
Is the light reflex more telling of the iris or the retina
Retina
32
Pupil size changes most in which light intensity
Mesopic
33
in dark adapted eyes, pupillary reactions occur at what intensities
Those below photopic range (rods)
| - parafovea and peripheral more sensitive
34
In normal light adapted eyes, which area of retina is more reactive
Fovea
| - Threshold is much higher
35
Does pupillary contraction speed change with light intensity
No, always constant
36
Pupils gradually return in what time
3-15 seconds
37
If the stimulus is very short, will the pupil still contract
Only if the stimulus is long enough to allow the retinal to register it
38
When light covers a greater area, what happens to the pupil
Constricts more
39
Pupil sums afferent impulses, regardless of
Station distribution (rods and cones)
40
Greater spatial frequency, the ____ the pupil contracts
Less
41
Why may hyperopes have a slightly smaller pupil
They have to accommodate more
42
Pupil size resulting in image degradation and glare
Larger pupils
43
If pupils are too _____, diffraction limit and reduced illumination can effect visual performance
Too small
44
Optimal pupil size
2mm
45
Pupil size does what with age
Decreases
46
Pupillary diameter range
2-8mm
47
Near vision traid
Convergence, miosis, accommodation
48
3rd nerve nucleus
Eddinger-westphal
49
Iris muscles are derived from
Neural ectoderm
50
Which iris muscle innervated by parasympathetic
Iris sphincter
51
Which iris muscle is innervated by sympathetic
Iris dilator
52
Which iris muscle is thicker
Dilator - 3-5 layers thick
53
Sensory, emotional, or mental stimuli elicit
Dilation
54
Pupil size during sleep and after death
Smaller
55
Stimuli become less arousing over time --> les pupillary reaction
Sensitization
56
High levels of IR
Burn bc of deep penetration
57
What happens to the sphincter when it is stimulated by heat
Contracts
58
If iritis ensues, what may be a feature
Long-lasting miosis
59
Structures of the angles from anterior to posterior
Schwalbe's line
Trabecular meshwork
Scleral spur
Ciliary body
60
What type of muscle is the ciliary muscle
Smooth (resembles skeletal)
61
3 functions of ciliary body
Aqueous production
Aqueous outflow
Accommodation
62
What accounts for 80-90% of aqueous production
Active secretion
63
What is higher in the aqueous than in the blood
Ascorbate (ascorbic acid)
64
What is higher in the blood than in the aqueous
Protein
65
Rate of aqueous production
2.5 microL/min
66
What time of day is there more aqueous production
During the day
67
How much does aqueous production rate decrease at night
50%
68
Diameter of zonular fibers
70-80nm
69
Purpose of zonular fibers
Stabilize lens
| Allow fluid to flow from PC to AC
70
At what age is accommodation typically completely lost
50
71
Why are some presbyopia still able to read, even though they cannot accommodate
Pupil constriction (miosis)
72
Zonular fibers during accommodation
Relaxes, less tension
73
When using distance vision, is the ciliary muscle relaxed or contracted
Relaxes
74
When using distance vision, are the zonular fibers relaxed or is their tension
Tension
75
During accommodation, is the ciliary muscle relaxed or contracted
Contracted
76
Why are dark iris's less effected by dilating drops
Pigmented epi and ciliary body bind with pharmaceutical agents
77
What is the cause of the decreased accommodation with age: lens or ciliary muscle
Thickening and stiffening of lens
78
When is there more aqueous outflow, during distance or near stimulation and why
Near bc the ciliary muscle contracts, opening the TM to allow aqueous to flow
79
Iris sphincter muscle is derived from
Neural ectoderm
80
Ciliary muscle is derived from
Mesoderm
81
Cells and flare visible in AH
Tyndall phenomenon
82
What is the Tyndall phenomenon due to
Breakdown of BAB
83
White collection at bottom of iris
Hypopyon
84
Blood settling in inferior iris from trauma
Hyphema
85
Which arterial circle is located in the iris
Major circle of iris
86
Clear, colorless fluid that fills the AC and PC
AH
87
Main function of AH
Inflate the globe and create IOP for normal optical functioning
88
Primary site of AH formation
Pars Plicata of ciliary processes
89
Which layer of epithelium forms AH
NPCE
90
Average rate of AH formation during the day
2.75microL/min
91
Average rate of AH formation at night
1.08 microL/min
92
What is 99.9% of normal AH
Water
93
Transport of blood to AH steps (5)
1. Blood to ciliary stroma
2. Solute from stroma in PCE cells
3. Thru GJ into NPCE
4. From NPCE to Post chamber (PC)
5. Osmotic gradient created facilitates the passive flow of water into the PC
94
3 mechanisms that solutes can move across the ciliary epithelium
Diffusion
Ultrafiltration
Active transport
95
Passive moment of solutes across ciliary epithelium due to a concentration gradient
Diffusion
96
Passive movement of water and water soluble substances across ciliary epithelium due to hydrostatic and oncotic pressure
Ultrafiltration
97
Energy consuming process against concentration gradient
Active transport
98
Major mechanism of transportation across ciliary epithelium
Active transport
99
What enzyme plays a key role in AH formation
Carbonic anhydrase
100
What would a carbonic anhydrase inhibitor do
Reduce AH formation
101
What would an alpha2 agonist do to AH formation
Reduce AH formation
102
What would a beta2 agonist do to AH formation
Increase AH formation
103
What could a beta antagonist do to AH formation
Decrease AH formation
104
Barrier to movement of intermediate and high molecular weight substances (like protein)
BAB
105
Protects eye from entry of toxic substances and maintains homeostatic control
BAB
106
Reason why drugs administered orally or IV hardly ever reach therapeutic levels in intraocular tissues
BAB
107
Type of connections between NPCE cells
Tight junctions
108
Type of connection between PCE and NPCE
Gap junctions
109
Which type of connection creates an effective barrier to proteins
tight junctions
110
What happens to the AH as the BAB breaks down
Becomes cloudy due to leakage of plasma proteins
111
2 major causes of BAB breakdown
Ocular injuries
| Ocular hypotonic
112
What is ocular hypotony
IOP of less than or equal to 5mmHg
113
Clear gel in posterior compartment of eye
VH
114
Makes up 80% of globe volume
VH
115
Located between lens and retina
VH
116
3 stages of vitreous development: 3-4 weeks gestation
Primary vitreous
117
3 stages of vitreous development: VEGF released by lens inducing vasculogensis; hyaloid artery penetration
Primary vitreous
118
3 stages of vitreous development: 6th gestation week
Secondary vitreous
119
3 stages of vitreous development: increasing size of vitreous cavity
Secondary vitreous
120
3 stages of vitreous development: hyaloid artery disappears leaving a tube of primary vitreous
Secondary vitreous
121
Tube of primary vitreous surrounded by secondary vitreous
Cloquet's canal
122
3 stages of vitreous development: secreted by NPCE of pars plana
Tertiary vitreous
123
Arises from center of optic disc; remnant of hyaloid artery
Bergmeister's papillae
124
Small opacity on posterior lens from the anterior attachment of hyaloid arter
Mittendorf's dot
125
Typically, where on the posterior lens is mittendorf's dot located
Nasally
126
Contains remnants of primary vitrous
Cloquet's canal
127
What can pass to the posterior chamber: ions, water, or protein
Ions and water
128
Can uveitis cause breakdown of BAB
Yes
129
Can diabetes cause breakdown of BAB
Yes
130
Can moderate dry eye cause BAB to breakdown
No
131
3 stages of vitreous development: zonular fibers
Tertiary vitreous
132
Outermost zone of vitreous
Vitreous cortex
133
Area of VH that is inner to the cortex and surrounds cloquet's canal
Intermediate zone
134
Middle layer of the eye
Uvea
135
The regions of the uvea from ant to post
Iris
Ciliary body
Choroid
136
From what 2 structures does the choroid extend from
Ora serrata to optic nerve
137
Layer between sclera and retina
Choroid
138
4 main layers of choroid (from sclera to retina)
Suprachoroid
Stroma
Choriocapillaris
Bruch's membrane
139
Single layer of fenestrated capillaries of the choroid
Choriocapillaris
140
Thin, pigmented, connective tissue layer of choroid
Suprachoroid
141
Layers of the choroid: Pigmented, vascularized, containing melanocytes, fibroblasts, macrophages, lymphocytes, mast cells
Stroma
142
Layer of the choroid that fuses with the retina
Bruch's membrane
143
What absorbs excess light in the choroid
Darkly pigmented choroid
144
Vascular choroid provides nutrient and removes wast from which layers of retina
Outer retina
145
Area of the macula devoid of vessels
Fovea avascular zone
146
Sole blood supply to foveal avascular zone
Choriocapillaries
147
What provides a path for the posterior vessels that supply the anterior segment
Suprachoroidal space of choroid
148
Arteries that supply the choroid
Ophthlamic a. --> ciliary a. --> 20 short post and 2 long posterior ciliary a.
149
Fibers carried by long ciliary nerves
Sensory and sympathetic fibers
150
Fibers carried by short ciliary nerves
Sympathetic and parasympathetic fibers
151
Provides a path for the nerves that supply the anterior segment
Suprachoroidal space of choroid
152
In hyperopic defocus, what happens the the thickness of the choroid
Thins
153
In hyperopic defocus, does choroidal growth increase or decrease
Increase
154
Myopic defocus, what happens to the thickness of choroid
Thickens
155
Myopic defocus causes the growth of choroid to what
Decrease
156
Can rapidly modulate its thickness, vary position of the retina and the state of focus
Choroid
157
4 main functions of the choroid
- provide nutrients and remove waste from outer retina
- passage of nerves and vessels
- absorption of excess light
- regulate emmetropization
158
3 aging changes in iris
- loss of pigmentation
- dilator becomes atrophic
- sphincter becomes sclerotic
159
Aging changes in ciliary body
Formation of aqueous humor decreases
| By 80 years, 25% of what it was
160
3 aging changes in choroid
- choriocapillaries decreases in density and diameter --> choroidal blood flow decreases
- bruch's membrane increases in thickness
- accumulations in bruch's membrane
161
5 layers of bruch's membrane from inner to outer
```
Basement membrane of RPE cells
Inner collagenous zone
Elastic layer
Outer collagenous zone
Interrupted basement membrane
```
162
Drusen accumulates in which layer of bruch's membrane
Inner collagenous layer
163
What is drusen made of
Lipofuscin
164
Yellow-brown pigment granules composed of lipid-containing residues from oxidative stress
Lipofusion
165
Difference between wet and dry AMD
Wet has neovascularization
166
Accumulation of water between RPE and Bruch's membrane can cause
Detachment
167
Accumulation of drusen makes Bruch's
Hydrophobic
168
Which layer is multilaminated sheet and fuses with RPE
Bruch's membrane
169
What provides blood to fovea region
Choriocapillaries
170
Which part of retina receives blood supply from choroid
Outer retina
171
Which layer of choroid proves a pathway for the vessels and nerves that supply the anterior segment
Suprachoroidal space
172
What happens to bruch's membrane with aging
Thickness increases
173
Which layer of bruch's membrane does drusen deposit
Inner collagenous zone
