B10 Flashcards
1
Q
The pupil that is seen is actually a _____ image of the ____ pupil
A
Magnified virtual image of the real object pupil
2
Q
Name the 7 functions of the iris
A
- improve visual clarity (regulates optical aberrations
- attraction/mate selection
- non verbal communication
- reduce glare
- control illumination
- prevent dazzling
- increase the depth of focus
3
Q
The iris separates the
A
Anterior and posterior chambers of the eye
4
Q
The iris is surrounded by what fluid?
A
Aqueous
5
Q
T/f: the iris is the most anterior portion of the uveal tract
A
True
6
Q
The iris rests lightly upon the ___
A
Lens
7
Q
What is the average diameter of the iris?
A
12mm
8
Q
The pupil center is slightly __ and ___ to the iris center
A
Slightly nasal and inferior
9
Q
An abnormally decentered pupil
A
Ectopic
10
Q
What does irregular or ectopic pupils do to optical quality
A
They degrade it
11
Q
The pupillary margin rests on the ___ surface of the lens
A
Anterior
12
Q
How does aqueous humor flow
A
It flows from the posterior–>anterior through the pupil
13
Q
T/F: Temporal iris in humans broader than nasal iris
A
True
14
Q
The posterior portion of the iris is derived from?
A
Neuroectoderm/neuroepithelium
15
Q
The dilator muscle is derived from the
A
Neuroepithelium
16
Q
The sphincter muscle is derived from the
A
Neuroepithelium
17
Q
The posterior pigmented epithelium is derived from the
A
Neuroepithelium
18
Q
The anterior portion of the iris is derived from
A
Mesoderm
19
Q
The iris stroma is derived from
A
Mesoderm
20
Q
The iris vessels is derived from
A
Mesoderm
21
Q
The iris nerves are derived from
A
Mesoderm
22
Q
The chromatophores are derived from
A
Mesoderm
23
Q
What are the 4 layers of the iris?
A
- anterior border layer
- stroma and sphincter muscle
- anterior epithelium and dilator muscle
- posterior epithelium
24
Q
What layer contains both mesoderm and ectoderm
A
Stroma and sphincter muscle
25
The reduction in optical aberrations and depth of focus is optimal at
2mm or less
26
What are the only elements in the iris that is capable of initiating movement
Iris muscles
27
What occurs in miosis (constriction if pupils)
the pupillary portion of iris gathers into pleats while the ciliary portion smooths out.
28
What occurs in mydriasis (dilation)
the stroma in the pupillary zone pulls flat while
| contraction furrows appear in the ciliary area.
29
T/F: blow flow is impeded by wither miosis or mydriasis
False. It is not impeded
30
T/F: in the past, it was believed that the stroma and blood vessels were responsible for iris movements, via elastic expansion, changes in hydration, and/or engorgement.
True
31
T/F: the stroma and iris vessels are elastic
False. They are not elastic
32
is a loose but orderly meshwork of collagen fibers with aqueous fluid and scissor like angles for folding
Stroma
33
Thin-walled layer of endothelium with an outer
| covering of collagen fibrils.
Iris vessels
34
The thickest portion of the iris
Stroma
35
What are the 4 functions of the stroma
- provides an anchor for structures
- protects the nerves and vessels from stretching and kinking
- adapts to constant movement
- folds and unfolds with minimal resistance to minimize energy expenditure
36
The stroma provides an anchor for what 4 structures?
- sphincter muscle
- dilator-posterior-epithelial plate
- iris nerve
- iris vessels
37
Structure that is more densely than deeper stroma
Anterior border layer
38
Dark brown spots that are compact masses of rounded cells filled with melanin
Nevi
39
T/F: the anterior border layer is more solid and dense with more layers in darkly pigmented eyes.
True
40
What kind of cells does the ABL have
Fibroblasts interlaced with melanocytes
41
T/F: In the ABL the iris is porous (no anterior limiting layer)
True
42
What gives us a blue iris
Light scatter in uniform space across stromal tissue
43
Why do most newborns start out with blue eyes then turn dark?
Because they haven't developed pigment yet
44
What causes dark irises?
Development of anterior stromal melanocytes and production of pigment
45
Blood flow of the iris is derived from
ophthalmic artery from two long posterior ciliary arteries and anterior ciliary arteries.
46
The anterior ciliary arteries run along the
Rectus muscles
47
T/F: the iris doe not bleed when its cut
True
48
There are 2 anterior ciliary arteries in each rectus muscles except for
Lateral rectus (it only has 1)
49
Allows for little distension and folding of vessels during constant movement of iris
Perivascular collagen sheaths
50
T/F: Perivascular collagen sheaths are unique to iris vessels
True
51
T/F" Humans react to light stimulation of the retina rather than the iris.
True
52
Light reflex is an important test to discover the integrity of the
- retina
- optic nerves
- chiasm
- optic tracts
53
The entire stimulus response function resembles a ___curve
S curve
54
The latency time becomes ____ with dimmer light stimuli
More prolonged
55
In scotopic and photopic conditions, the pupil_____with variability in light
Doesnt really change all that much
56
In mesopic conditions, the pupil_____with variability in light
Changes a lot
57
In the dark adapted state, the threshold light of intensity needed to produce a pupil contraction becomes ___ as rods are brought into play
Less
58
T/F: Rods in the dark adapted state do not produce as much increase in pupil contraction in response to increases in stimulus intensity
True
59
In dark-adapted eyes, pupillary reactions occur at intensities
Below photopic range
60
In dark adapted eyes the parafovea and peripheral are ____ sensitive than the fovea
More
61
In normal light adapted eyes, pupillary threshold is
Much higher
62
In normal light adapted eyes, the fovea is ___reactive than the periphery
More
63
T/F: the pupil has a max speed to contract
True. Not matter the intensity of light the pupil will contract at the same speed
64
What is the max speed of pupil contraction?
4 Hz
65
T/F: The pupil has to be able to see a stimulus long enough for it to react
True
66
With longer duration of a stimulus, the pupil contracts___, there is a ___latency time, and the contraction lasts ___
- contracts more
- shorter latency times
- contraction lasts longer
67
The pupil is more constricted when the light covers a ____ area and when light is ____bright
Covers a greater area and light is equally bright
68
T/F: Pupils sums afferent impulses regardless of spatial distribution, both rods and cones.
True
69
Under dark adaptation, the fovea shows ___ sensitivity compared to surrounding retinal areas because of the lack of rods
Decreased
70
In mesopic and photopic adaptations the pupil responds greatest in the ___ field
Central
71
T/F: the temporal field response is usually greater than the nasal field response
True
72
The peak sensitivity under photopic conditions is
Green 550
73
The peak sensitivity under scotopic conditions is
Blue
74
The greater the spatial frequency, the ___ the pupil contracts
Less
75
20/20 has a ___ spatial frequency
High
76
T/F: The pupil responds to motion even when the light level stays the same
True
77
Some people think that myopes have ___ pupils and hyperopes have ___ pupils
Myopes: larger pupils
Hyperopes: smaller pupils
78
Larger pupils can result in what 2 things
- Image degradation
| - glare
79
If the pupils are too small (<2mm) what 2 things can effect visual performance
- diffraction limited
| - reduced illumination
80
What is the optimal pupil size?
2mm
81
Does pupil size increase of decrease with age?
Decreases
82
The pupil diameter can vary between?
2-8 mm
83
What is the near vision triad?
Convergence, miosis, and accommodation
84
What is the 3rd nerve nucleus?
Eddinger-Westphal
85
Amplitude for young people is ___ to contraction from bright light
Equal
86
Is iris sphincter and dilator muscle is derived from
Neuroectoderm
87
The iris sphincter is predominately innervated by
The parasympathetic system
88
The iris dilator is predominately innervated by?
The sympathetic system
89
T/F: the sphincter and dilator muscle are equally strong
True
90
When are the pupils smaller?
During sleep and death
91
When are the pupils bigger?
During waking hours and when frightened
92
What 3 things can elicit a pupillary dilation?
- sensory
- emotion
- mental
93
If something is less arousing how will this effect a pupillary reaction?
There will be less of a pupillary response
94
If you are infuriated, will you have a greater or lesser pupillary reaction?
Greater
95
What are some findings of pupil size in adults
- they can still respond fully to mydriatic drugs
- pupils are still round and smooth
- light reflex remain brisk
- reduction is size is a linear process
- no change in thickness of dilator muscle with age
- decreasing pupil size begin in healthy eyes with strong levels or accommodation and brisk reactive pupils
96
If someone has horners syndrome what happens to the pupil when you put cocaine in their eye?
The horners pupil dilates less than the normal pupil
97
What does cocaine do to the eye?
blocks the reuptake of post-ganglionic norepi
| resulting in the dilation of a normal pupil from retention of norepi in the synapse.
98
What can high levels of infrared do to the eye?
It can burn any ocular structure and have very deep penetration
99
What layer of the iris absorbs heat?
The black pigment of the posterior iris layer
100
When stimulated directly by heat, what happens to the iris sphincter?
It contracts
101
If the iris ensues, what may occur?
Long-lasting miosis
102
T/F: the ciliary body contains the minor arterial circle of the iris
False
103
What is the most posterior structure when looking doing gonio?
Ciliary body
104
What is the most anterior structure when doing gonio?
Schwalbes line
105
Name the order from anterior to posterior when doing gonio
Schwalbes line--> trabecular meshwork --> scleral spur --> ciliary body
106
Name the 4 functions of the ciliary body?
- accommodation
- aqueous production
- aqueous outflow
- indirectly causes iris contraction
107
What does aqueous production do?
Supplies nutrients to the lens and cornea
108
What does aqueous outflow do?
- Maintains IOP
| - removes waste products
109
What are the 3 main process to produce/secretary aqueous humor?
- diffusion
- ultrafiltration
- active secretion
110
The stroma within the ciliary processes contains a dense network of ____ capillaries, and the number and shape of the processes provides a large ____ for secretion into the posterior chamber.
- fenestrated capillaries
| - large surface area
111
Active secretion accounts for ___ of aqueous production
80-90%
112
What is the most significant factor in aqueous production?
Active secretion
113
What facilitates water movement
- coordination of ion pumps, channels
- cotransporters in the 2 epithelial
- aquaporins
114
What primarily drives secretion in the posterior chamber?
Movement of Na+ and Cl-
115
What has an indirect role in moderating the Cl flux
Bicarbonate
116
What is the rate of aqueous production?
2.5 ul per minute
117
This substance is a metabolic waste produce of glycolysis of the lens and cornea and is in high concentrations in the aqueous
Lactate
118
Ascorbate concentration is ___ higher in the aqueous than in blood plasma
20x
119
If aqueous produced more during the day or night?
Day. Decreased 50% at night
120
T/F: Dilating and constricting blood vessels can influence aqueous blood vessels by increasing and decreasing blood volume.
True
121
Diameter of zonular fibers
70-80mm
122
Elastic fibers that stabilize the lens and allows fluid to flow from the posterior chamber to the vitreous. And attaches to the lens
Zonular fibers
123
When is accommodation lost?
Age 50
124
Describe accommodation
Contraction of the longitudinal fibers of the ciliary muscle pulls the choroid forward, and contraction of the circular fibers draws the CB closer to the lens, decreasing the diameter of the ring formed by the CB. This releases tension on the zonule fibers and allows the lens capsule
to adopt a more spherical shape.
125
During accommodation the lens ____ ,the anterior surface curve ____, zonular fibers ____, the lens capsules becomes a more ___shape, and _____ refractive power
```
The lens thickens
The anterior curve increases
Zonular fibers relax
Lens capsule becomes more spherical shape
Increases refractive power
```
126
When looking at a distance, the ciliary muscle is ___ and the zonular fibers are ___
The ciliary muscle is relaxed
| The zonules are pullin on the lens capsule
127
Pilocarpine cases ciliary muscle ____
Contraction
128
Does accommodative amplitude decrease or increase with age
Decrease
129
What stimulates miosis
Accommodation and convergence
130
Subjective measurements of accommodation rely on
Perception of clarity
131
Objective measurements of accommodation can be obtained with an
Autorefractor or aberrometer
132
T/F: dynamic measurements are better than static measurements
True
133
What really effects presbyopic eye movement?
The lens becoming thicker and stiffer
134
T/F: reduced near vision is caused by significant reduction in strength of ciliary muscle
False. It is not caused by it
135
What are some structural changes in the aging eye that could lead to reduced contractile force?
- thickening of tendons
- reduced muscle mass
- increased connective tissue
136
T/F: Measurements of contractile strength of ciliary muscle strips with stimulation show no reduction with increasing age.
True
137
In presbyopes are there changes in M receptor numbers, binding affinity, or ACh activity?
No
138
Loss of the ability to accommodate
Presbyopia
139
Ciliary muscle contractive power ___ up until age that
| presbyopia manifests.
Increases
140
Are there changes in zonular length with age?
No
141
What is the limiting factor for accommodation
The movement and shape of the lens
142
Why can ciliary muscle contraction change the configuration of the TM?
And what does this do?
Because some of the longitudinal fibers are attached to the TM sheets
Facilitates aqueous movement through the anterior chamber angle structures
143
What is the max reductions of IOP when dealing with accommodation?
2.38mmHg
144
The ciliary muscle is derived from
Mesoderm
145
Describe the Tyndall phenomenon
- When breakdown of blood-aqueous barrier occurs, cells and flare become visible.
- Often immune factors, leucocytes.
- Usually whitish
- Can form hypopyon
146
What is hyphema?
-Trauma to head or injury such as whiplash can tear/ break the iris
-This can break the iris blood vessels entering from the major circle of
the iris
-Blood settles inferiorly.
147
A clear, colorless fluid that fills the anterior
| and posterior chamber of the eye
Aqueous Humor
148
What are the 4 functions of the AH?
-Supplies nutrients and oxygen to and remove metabolic wastes from the anterior intraocular tissues such as cornea, lens and TM
-Inflates the eye globe and creates an IOP for normal optical functioning of the eye
-Transports ascorbic acid(AA) into anterior segment where it
serves as an antioxidative agent
-Facilitates the local immune responses during inflammation and
infection
149
What is the primary site of AH formation?
Pars plicata
150
Which layer of the CE is necessary for AH formation?
Non-pigmented epithelium
151
What is the major mechanism of solutes across CE?
Active transport
152
What drugs reduce aqueous humor formation?
CAI and alpha 2 agonists
153
Which one has a higher concentration of protein? (Blood plasma or aqueous humor)
Blood plasma
154
Which one has a higher concentration of ascorbic acid? (Blood plasma or aqueous humor)
Aqueous humor
155
Beta 2 agonist ___aqueous humor formation
Increases
156
Is AH average rate of formation greater or less during the daytime?
Greater (2.75 ul/min)
157
What is the pathway (5 steps) of the blood to the AH?
1.) Blood flow-->vascular bed of ciliary stroma
2.) Loading of solute from the ciliary stroma blood into the PE cells
3.) Translocation of solute through the gap junction into the NPE
cells
4.) Exclusion of solute from the NPE cells to the posterior
chamber (driven by an electrochemical gradient and/or by
active transport)
5.) The osmotic gradient established by the solutes facilitates the
passive flow of water into the posterior chamber by osmosis
158
What are the 3 mechanisms of solutes across the CF?
- Diffusion
- ultrafiltration
- active transport
159
Defined as the passive movement of solutes across the CE in response to a concentration gradient
Diffusion
160
defined as the passive movement of water and water soluble substances across cell membranes as a result of the hydrostatic and oncotic pressure between the ciliary stroma and the AH
Ultrafiltration
161
an energy-consuming process involving the movement of solutes across the CE against their concentrations gradients
Active transport
162
Will people who smoke marijuana have increased or decreased IOP?
What causes this?
Decreased IOP
9-THC
163
Is IOP constant throughout the day?
No
164
Why don't we want a lot of protein in the AH?
Because we want to keep transparency
165
What is the major part of the blood aqueous barrier?
Tight junctions between NPCE cells
166
What 2 things are allowed to pass to the posterior chamber?
Ions and water
167
What is a part of the primary vitreous
Hyaloid artery
168
What are the 3 conditions with remnants of the hyaloid artery?
- cloquets canal
- bergmeisters papillae
- mittendorfs dot
169
What is the outermost zone of the vitreous?
Vitreous cortex also called hyaloid surface
170
What is the center zone of the vitreous called?
Cloquets Canal (hyaloid canal)
171
What is the intermediate zone of the vitreous?
Inner to the cortex and surrounds the center canal
172
Where does AH come from?
Blood plasma
173
Barrier to the movement of intermediate- and high-
| molecular weight substances such as protein.
Blood aqueous barrier
174
Barrier protecting the eye from entry of toxic substances and maintaining the homeostatic control
Blood aqueous barrier
175
Barrier that explains why drugs administered orally
or IV can hardly reach therapeutic levels in
intraocular tissue
Blood aqueous barrier
176
Tight junctions are present in the ____ ciliary epithelium
Non-pigmented ciliary epithelium (NPCE)
177
Other than NPCE where are tight junctions also present?
- in the iridial vascular endothelium
| - between the iris epithelial
178
Endothelial of the inner wall of _____ are tight joined to prevent retrograde movement of solutes and fluid from the canal lumen into the AC
Schlemms canal
179
Tight junctions between NPCE cells constitute an effective barrier to intermediate and high molecular weight substances such as ____
proteins
180
What happens to the aqueous when there is a breakdown of the BAB?
And what cells may also be present?
Aqueous becomes cloudy due to leakage of plasma proteins into the posterior chamber (PC) and anterior chamber (AC).
Inflammatory cells may also be present.
181
In anterior uveitis what 2 things will you see?
Cells and flares (proteins)
182
Breakdown of the BAB can cause what 2 eye conditions?
- Anterior uveitis
| - hyphema
183
Blood in the anterior segment due to trauma
Hyphema
184
What are 4 ocular injuries that causes or is caused by BAB breakdown
- Surgical and non-surgical traumas
- ---hyphema
- Intraocular inflammation (such as uveitis)
- Vascular and systemic disorders (such as diabetes)
- Intraocular tumor
185
is usually defined as an IOP of 5 mm Hg or less (extremely low pressures)
Ocular hypotony
186
When there is ocular inflammation what 2 things are releases?
- cytokines
| - growth factors
187
Clear gel which occupies the posterior compartment of the eye.
Vitreous
188
The vitreous is located between the ___ and the ___
Retina and lens
189
The vitreous occupies ___ of the volume of the eye
80%
190
Light initially entering the eye through the
cornea, pupil and lens, is transmitted through the
____ to the ____
Vitreous --> retina
191
3-4 gestational stage of the vitreous
Primary vitreous
192
6th gestational week of vitreous
Secondary vitreous
193
Zonular fibers are in the ___ vitreous
Tertiary
194
Is secreted by NPCE of pars plana and persists in the
| adult as the suspensory ligament of the lens
Zonular fibers (tertiary vitreous)
195
Optic cup filed by a system of fibrillar material, presumably secreted by embryonic retina cells is during what stage of vitreous development?
Primary vitreous
196
VEGF released by lens induces vasculogenesis; Hyaloid artery penetration is a part of what vitreous developmental stage?
Primary vitreous
197
Vitreous stage where Anti-angiogenesis factor present, Hyaloid vessels retract, Vitreous gel body formed
Secondary vitreous
198
arises from the center of the optic disc, consists of a small tuft of fibrous tissue and represents a remnant of the fetal hyaloid artery.
Bergmeister's papillae
199
small, circular opacity on the posterior lens capsule, classically nasal in location, which represents the anterior attachment of the hyaloid artery.
Mitterndorfs dot
200
a tubular structure containing remnants of the primary vitreous, located between the posterior aspect of the lens and the retina in the vicinity of the optic disk
Cloquets canal (hyaloid canal)
201
The pigmented and nonpigmented CE are connected by
Gap junctions
Apex to apex
202
The middle layer of the eye
Uvea
203
What are the 3 regions of the uvea?
- iris
- CB
- choroid
204
The choriod extends from the ___ to the ___
Ora serrata to the optic nerve
205
The choroid is located between the ___ and the ___
Sclera and retina
206
Layer of the choroid that is thin, pigmented, connective tissue
Suprachoroid
207
Pigmented, vascularized, loose connective tissue that contains melanocytes, fibroblasts, macrophages, lymphocytes, mast cells
Large and medium vessels
208
A later of the choroid that is a single layer of fenestrated capillaries
Choriocapillaris
209
This layer of the choroid fuses with the retina multilaminated sheet
Bruchs membrane
210
____choriod absorbs excess light
Darkly pigmented
211
Provides nutrients to and remove the waste products from outer retina
Vascular choroid
212
Sole blood supply to the fovea
Choriocapillaries
213
Provides a pathway for the posterior vessels that supply the anterior segment
Suprachoroidal space
214
A branch of the ophthalmic artery
Ciliary artery
215
What are the 2 branches of the ciliary artery
Short posterior ciliary artery and long posterior ciliary arteries
216
Long ciliary nerves carries ___ and ___ fibers
Sensory and sympathetic fibers
217
Short ciliary nerves carry ___ and ___fibers
Sympathetic and parasympathetic
218
Provides a pathway for the nerves that supply the anterior segment
Suprachoroidal space of choroid
219
If someone has a hyperopic defocus the choroid will be ___ and the growth is ______
Thin choroid and growth increased
220
If someone has a myopic defocus the choroid will be ___ and the growth is ______
Thick choroid and growth decreased
221
The choroid can ___ modulates its thickness, varying the position of the retina and the state of focus of the eye
Rapidly
222
What are the 4 functions of the choroid?
- Provide nutrients and remove the waste products from outer retina
- Passage of nerves and vessels
- Absorption of excess light
- Regulate emmetropization (study in chicken)
223
What are the 3 changes in the iris?
- loss of pigmentation
- dilator muscle becomes atrophic
- sphincter muscle becomes sclerotic
224
What are the 2 aging changes in the ciliary body
- elasticity decreased due to the amount of connective tissue increased within the layer of the CB
- formation of aqeuous humor decreases with aging
225
What are the 3 aging changes in the choroid?
- choriocapillaries decrease in density and diameter-->choroidal blood flow decreases
- bruchs membrane increases in thickness
- various substance and particles accumulates in bruchs membrane
226
Nutrients from the choriocapillaries and waste product from the retina pass through what structure?
Bruchs membrane
227
Name the 5 layers of the bruchs membrane
1. ) interrupted basement membrane
2. ) outer collagenous zone
3. ) elastic layer
4. ) inner collagenous zone
5. ) basement membrane of RPE cells
228
Calcification and the yellow deposits in the inner collagenous layer of Bruch’s membrane. Made of the remaining damaged cells (called lipofuscin) from the oxidative stress.
Drusen
229
yellow-brown pigment granules composed of lipid-containing residues form oxidative stress
Lipofuscin
230
Does the accumulation of drusen make Bruchs hydrophobic or hydrophilic?
Hydrophobic
231
T/F: the accumulate of drusen inhibits the passage of metabolites
True
232
Accumulation of water between RPE and bruchs membrane causes _____
Detachment
233
Stage of ARMD where the choroid still functions
Dry ARMD
234
What layer of the choroid is multilaminated sheet and fuses with RPE?
Bruchs membrane
235
What provides blood to the fovea region?
Choriocapillaries
236
What part of the retina receives blood supply from choroid?
Outer retina
237
Which layer of the choroid proves a pathway for the vessels and nerves that supply the anterior segment?
Suprachoroidal space
238
Which layer of Bruchs membrane does drusen deposit?
Inner collagenous zone
239
Bruchs membrane thickness ___ with aging
Increases
240
With pupil constriction you have a ____depth of field
Larger
241
Low concentration of proteins in aqueous helps prevent ___
Light scatter
242
Are there large amounts of protein in the aqueous?
No
