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Ocular Phys > Block10 > Flashcards

Block10 Flashcards

1
Q

The pupil that is seen is actually a

A

Magnified virtual image of the real object pupil

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2
Q

Separates AC and PC

A

Iris

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3
Q

How much is the iris magnified by when viewed through the cornea

A

1/8th

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4
Q

Average iris diameter

A

12 mm

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5
Q

Thinnest point of the iris is

A

At the iris root - 500 microns

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6
Q

Where is normal pupil center

A

Slightly inferionasal

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7
Q

Abnormal decentered pupil

A

Ectopic

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8
Q

Which area of the iris is broader in humans

A

Temporal iris

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9
Q

Largest eyes in animal kingdom

A

Giant squid

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10
Q

Largest eyes relative to body size

A

Tarsier

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11
Q

Posterior iris is derived from

A

Neuroepithelium

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12
Q

What structures of the iris are derived from neuroepithlium

A

Dilator muscle
Sphincter muscle
Posterior pigmented epithelium

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13
Q

Anterior portion of the iris is derived from

A

Mesoderm

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14
Q

What iris structures are derived from mesoderm

A

Stroma
Vessels
Nerves
Chromatophores

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15
Q

4 layers of the iris (anterior to posterior)

A

Anterior border layer
Stroma
Anterior epithelium and dilator muscle
Posterior pigmented epithelium

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16
Q

Which layer contains both mesoderm and ectoderm

A

Stroma and sphincter muscle

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17
Q

3 main functions of the pupil

A

Control of retinal illumination
Reduction in optical aberrations
Depth of focus

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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
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19
Q

Pupillary portion of iris gathers into pleats while ciliary portion smooths out: miosis or mydriasis

A

Miosis

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20
Q

Stromal pulls flat while contraction furrow appear in ciliary area: miosis or mydriasis

A

Mydriasis

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21
Q

Thickest portion of iris

A

Stroma

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22
Q

Function of stroma

A

Anchor for

  • sphincter muscle
  • dilator-posterior-epithelial plate
  • iris nerves
  • iris vessels
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23
Q

Is the iris considered porous

A

Yes

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24
Q

Newborns typically have what colored iris? Can it change?

A

Blue; yes

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25
Q

What causes iris to change colors

A

Development of anterior stromal melanocytes and production of pigment granules

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26
Q

What colored iris are more dominant

A

Darker colors

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27
Q

Blood flow to iris is derived from

A

Ophthalmic artery and 2 long posterior ciliary arteries and anterior ciliary arteries

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28
Q

Anterior ciliary arteries run along

A

Recti muscles

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29
Q

How many anterior ciliary arteries run along each recti muscle

A

2, except LR only has 1

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30
Q

Unique to the iris vessels and found nowhere else in the body

A

Perivascular collagen sheaths

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31
Q

Is the light reflex more telling of the iris or the retina

A

Retina

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32
Q

Pupil size changes most in which light intensity

A

Mesopic

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33
Q

in dark adapted eyes, pupillary reactions occur at what intensities

A

Those below photopic range (rods)

- parafovea and peripheral more sensitive

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34
Q

In normal light adapted eyes, which area of retina is more reactive

A

Fovea

- Threshold is much higher

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35
Q

Does pupillary contraction speed change with light intensity

A

No, always constant

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36
Q

Pupils gradually return in what time

A

3-15 seconds

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37
Q

If the stimulus is very short, will the pupil still contract

A

Only if the stimulus is long enough to allow the retinal to register it

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38
Q

When light covers a greater area, what happens to the pupil

A

Constricts more

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39
Q

Pupil sums afferent impulses, regardless of

A

Station distribution (rods and cones)

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40
Q

Greater spatial frequency, the ____ the pupil contracts

A

Less

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41
Q

Why may hyperopes have a slightly smaller pupil

A

They have to accommodate more

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42
Q

Pupil size resulting in image degradation and glare

A

Larger pupils

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43
Q

If pupils are too _____, diffraction limit and reduced illumination can effect visual performance

A

Too small

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44
Q

Optimal pupil size

A

2mm

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45
Q

Pupil size does what with age

A

Decreases

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46
Q

Pupillary diameter range

A

2-8mm

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47
Q

Near vision traid

A

Convergence, miosis, accommodation

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48
Q

3rd nerve nucleus

A

Eddinger-westphal

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49
Q

Iris muscles are derived from

A

Neural ectoderm

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50
Q

Which iris muscle innervated by parasympathetic

A

Iris sphincter

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51
Q

Which iris muscle is innervated by sympathetic

A

Iris dilator

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52
Q

Which iris muscle is thicker

A

Dilator - 3-5 layers thick

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53
Q

Sensory, emotional, or mental stimuli elicit

A

Dilation

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54
Q

Pupil size during sleep and after death

A

Smaller

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55
Q

Stimuli become less arousing over time –> les pupillary reaction

A

Sensitization

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56
Q

High levels of IR

A

Burn bc of deep penetration

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57
Q

What happens to the sphincter when it is stimulated by heat

A

Contracts

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58
Q

If iritis ensues, what may be a feature

A

Long-lasting miosis

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59
Q

Structures of the angles from anterior to posterior

A

Schwalbe’s line
Trabecular meshwork
Scleral spur
Ciliary body

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60
Q

What type of muscle is the ciliary muscle

A

Smooth (resembles skeletal)

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61
Q

3 functions of ciliary body

A

Aqueous production
Aqueous outflow
Accommodation

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62
Q

What accounts for 80-90% of aqueous production

A

Active secretion

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63
Q

What is higher in the aqueous than in the blood

A

Ascorbate (ascorbic acid)

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64
Q

What is higher in the blood than in the aqueous

A

Protein

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65
Q

Rate of aqueous production

A

2.5 microL/min

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66
Q

What time of day is there more aqueous production

A

During the day

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67
Q

How much does aqueous production rate decrease at night

A

50%

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68
Q

Diameter of zonular fibers

A

70-80nm

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69
Q

Purpose of zonular fibers

A

Stabilize lens

Allow fluid to flow from PC to AC

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70
Q

At what age is accommodation typically completely lost

A

50

71
Q

Why are some presbyopia still able to read, even though they cannot accommodate

A

Pupil constriction (miosis)

72
Q

Zonular fibers during accommodation

A

Relaxes, less tension

73
Q

When using distance vision, is the ciliary muscle relaxed or contracted

A

Relaxes

74
Q

When using distance vision, are the zonular fibers relaxed or is their tension

A

Tension

75
Q

During accommodation, is the ciliary muscle relaxed or contracted

A

Contracted

76
Q

Why are dark iris’s less effected by dilating drops

A

Pigmented epi and ciliary body bind with pharmaceutical agents

77
Q

What is the cause of the decreased accommodation with age: lens or ciliary muscle

A

Thickening and stiffening of lens

78
Q

When is there more aqueous outflow, during distance or near stimulation and why

A

Near bc the ciliary muscle contracts, opening the TM to allow aqueous to flow

79
Q

Iris sphincter muscle is derived from

A

Neural ectoderm

80
Q

Ciliary muscle is derived from

A

Mesoderm

81
Q

Cells and flare visible in AH

A

Tyndall phenomenon

82
Q

What is the Tyndall phenomenon due to

A

Breakdown of BAB

83
Q

White collection at bottom of iris

A

Hypopyon

84
Q

Blood settling in inferior iris from trauma

A

Hyphema

85
Q

Which arterial circle is located in the iris

A

Major circle of iris

86
Q

Clear, colorless fluid that fills the AC and PC

A

AH

87
Q

Main function of AH

A

Inflate the globe and create IOP for normal optical functioning

88
Q

Primary site of AH formation

A

Pars Plicata of ciliary processes

89
Q

Which layer of epithelium forms AH

A

NPCE

90
Q

Average rate of AH formation during the day

A

2.75microL/min

91
Q

Average rate of AH formation at night

A

1.08 microL/min

92
Q

What is 99.9% of normal AH

A

Water

93
Q

Transport of blood to AH steps (5)

A
  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
Q

3 mechanisms that solutes can move across the ciliary epithelium

A

Diffusion
Ultrafiltration
Active transport

95
Q

Passive moment of solutes across ciliary epithelium due to a concentration gradient

A

Diffusion

96
Q

Passive movement of water and water soluble substances across ciliary epithelium due to hydrostatic and oncotic pressure

A

Ultrafiltration

97
Q

Energy consuming process against concentration gradient

A

Active transport

98
Q

Major mechanism of transportation across ciliary epithelium

A

Active transport

99
Q

What enzyme plays a key role in AH formation

A

Carbonic anhydrase

100
Q

What would a carbonic anhydrase inhibitor do

A

Reduce AH formation

101
Q

What would an alpha2 agonist do to AH formation

A

Reduce AH formation

102
Q

What would a beta2 agonist do to AH formation

A

Increase AH formation

103
Q

What could a beta antagonist do to AH formation

A

Decrease AH formation

104
Q

Barrier to movement of intermediate and high molecular weight substances (like protein)

A

BAB

105
Q

Protects eye from entry of toxic substances and maintains homeostatic control

A

BAB

106
Q

Reason why drugs administered orally or IV hardly ever reach therapeutic levels in intraocular tissues

A

BAB

107
Q

Type of connections between NPCE cells

A

Tight junctions

108
Q

Type of connection between PCE and NPCE

A

Gap junctions

109
Q

Which type of connection creates an effective barrier to proteins

A

tight junctions

110
Q

What happens to the AH as the BAB breaks down

A

Becomes cloudy due to leakage of plasma proteins

111
Q

2 major causes of BAB breakdown

A

Ocular injuries

Ocular hypotonic

112
Q

What is ocular hypotony

A

IOP of less than or equal to 5mmHg

113
Q

Clear gel in posterior compartment of eye

A

VH

114
Q

Makes up 80% of globe volume

A

VH

115
Q

Located between lens and retina

A

VH

116
Q

3 stages of vitreous development: 3-4 weeks gestation

A

Primary vitreous

117
Q

3 stages of vitreous development: VEGF released by lens inducing vasculogensis; hyaloid artery penetration

A

Primary vitreous

118
Q

3 stages of vitreous development: 6th gestation week

A

Secondary vitreous

119
Q

3 stages of vitreous development: increasing size of vitreous cavity

A

Secondary vitreous

120
Q

3 stages of vitreous development: hyaloid artery disappears leaving a tube of primary vitreous

A

Secondary vitreous

121
Q

Tube of primary vitreous surrounded by secondary vitreous

A

Cloquet’s canal

122
Q

3 stages of vitreous development: secreted by NPCE of pars plana

A

Tertiary vitreous

123
Q

Arises from center of optic disc; remnant of hyaloid artery

A

Bergmeister’s papillae

124
Q

Small opacity on posterior lens from the anterior attachment of hyaloid arter

A

Mittendorf’s dot

125
Q

Typically, where on the posterior lens is mittendorf’s dot located

A

Nasally

126
Q

Contains remnants of primary vitrous

A

Cloquet’s canal

127
Q

What can pass to the posterior chamber: ions, water, or protein

A

Ions and water

128
Q

Can uveitis cause breakdown of BAB

A

Yes

129
Q

Can diabetes cause breakdown of BAB

A

Yes

130
Q

Can moderate dry eye cause BAB to breakdown

A

No

131
Q

3 stages of vitreous development: zonular fibers

A

Tertiary vitreous

132
Q

Outermost zone of vitreous

A

Vitreous cortex

133
Q

Area of VH that is inner to the cortex and surrounds cloquet’s canal

A

Intermediate zone

134
Q

Middle layer of the eye

A

Uvea

135
Q

The regions of the uvea from ant to post

A

Iris
Ciliary body
Choroid

136
Q

From what 2 structures does the choroid extend from

A

Ora serrata to optic nerve

137
Q

Layer between sclera and retina

A

Choroid

138
Q

4 main layers of choroid (from sclera to retina)

A

Suprachoroid
Stroma
Choriocapillaris
Bruch’s membrane

139
Q

Single layer of fenestrated capillaries of the choroid

A

Choriocapillaris

140
Q

Thin, pigmented, connective tissue layer of choroid

A

Suprachoroid

141
Q

Layers of the choroid: Pigmented, vascularized, containing melanocytes, fibroblasts, macrophages, lymphocytes, mast cells

A

Stroma

142
Q

Layer of the choroid that fuses with the retina

A

Bruch’s membrane

143
Q

What absorbs excess light in the choroid

A

Darkly pigmented choroid

144
Q

Vascular choroid provides nutrient and removes wast from which layers of retina

A

Outer retina

145
Q

Area of the macula devoid of vessels

A

Fovea avascular zone

146
Q

Sole blood supply to foveal avascular zone

A

Choriocapillaries

147
Q

What provides a path for the posterior vessels that supply the anterior segment

A

Suprachoroidal space of choroid

148
Q

Arteries that supply the choroid

A

Ophthlamic a. –> ciliary a. –> 20 short post and 2 long posterior ciliary a.

149
Q

Fibers carried by long ciliary nerves

A

Sensory and sympathetic fibers

150
Q

Fibers carried by short ciliary nerves

A

Sympathetic and parasympathetic fibers

151
Q

Provides a path for the nerves that supply the anterior segment

A

Suprachoroidal space of choroid

152
Q

In hyperopic defocus, what happens the the thickness of the choroid

A

Thins

153
Q

In hyperopic defocus, does choroidal growth increase or decrease

A

Increase

154
Q

Myopic defocus, what happens to the thickness of choroid

A

Thickens

155
Q

Myopic defocus causes the growth of choroid to what

A

Decrease

156
Q

Can rapidly modulate its thickness, vary position of the retina and the state of focus

A

Choroid

157
Q

4 main functions of the choroid

A
  • provide nutrients and remove waste from outer retina
  • passage of nerves and vessels
  • absorption of excess light
  • regulate emmetropization
158
Q

3 aging changes in iris

A
  • loss of pigmentation
  • dilator becomes atrophic
  • sphincter becomes sclerotic
159
Q

Aging changes in ciliary body

A

Formation of aqueous humor decreases

By 80 years, 25% of what it was

160
Q

3 aging changes in choroid

A
  • choriocapillaries decreases in density and diameter –> choroidal blood flow decreases
  • bruch’s membrane increases in thickness
  • accumulations in bruch’s membrane
161
Q

5 layers of bruch’s membrane from inner to outer

A 
Basement membrane of RPE cells
Inner collagenous zone
Elastic layer
Outer collagenous zone
Interrupted basement membrane
162
Q

Drusen accumulates in which layer of bruch’s membrane

A

Inner collagenous layer

163
Q

What is drusen made of

A

Lipofuscin

164
Q

Yellow-brown pigment granules composed of lipid-containing residues from oxidative stress

A

Lipofusion

165
Q

Difference between wet and dry AMD

A

Wet has neovascularization

166
Q

Accumulation of water between RPE and Bruch’s membrane can cause

A

Detachment

167
Q

Accumulation of drusen makes Bruch’s

A

Hydrophobic

168
Q

Which layer is multilaminated sheet and fuses with RPE

A

Bruch’s membrane

169
Q

What provides blood to fovea region

A

Choriocapillaries

170
Q

Which part of retina receives blood supply from choroid

A

Outer retina

171
Q

Which layer of choroid proves a pathway for the vessels and nerves that supply the anterior segment

A

Suprachoroidal space

172
Q

What happens to bruch’s membrane with aging

A

Thickness increases

173
Q

Which layer of bruch’s membrane does drusen deposit

A

Inner collagenous zone

Ocular Phys (5 decks)

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