Aqueous Flashcards
1
Q
What are the aqueous compartments
A
Anterior chamber and posterior chamber
2
Q
What are the anterior and posterior chambers separated by
A
Iris
3
Q
What does the iris act as
A
One way valve
4
Q
What is the direction of the flow of aqueous
A
Unidirectional, posterior to anterior
5
Q
Why don’t we want RBCs and protein in aqueous
A
Cloud vision
6
Q
Jobs of the aqueous
A
- clear fluid that pressurized the eye
- provides nutrients to avascular structures
7
Q
What produces the aqueous
A
Ciliary body
8
Q
Where does aqueous exit the eye
A
Iridocorneal angle
9
Q
What is the main drainage structure of the aqueous
A
Trabecular mesh work
10
Q
What are the avascular structures that the aqueous provides nutrients for
A
Lens
Cornea
Trabecular mesh work
11
Q
Central boundary of the posterior chamber
A
Capsule of the crystalline lens
12
Q
Posterior boundary of the posterior chamber
A
Anterior hyaloid face of the vitreous body
13
Q
Peripheral boundary of the posterior chamber
A
Non-pigmented ciliary epithelium of ciliary body
14
Q
Anteiror border of hte posteiror chamber
A
Posterior pigment layer of the iris
15
Q
Why does the aqueous not pass through the iris
A
Because of tight junctions between posteiror pigment epithelium of iris
16
Q
Volume of aqueous in the posterior chamber
A
50 to 65 microliters
17
Q
What are the 3 sub compartments of the posteiror chamber
A
- Retrozonular
- Zonular
- Pre zonular
18
Q
This is the space between the posteiror zonules and anteiror hylaoid face of the vitreous body
A
Retro zonular compartment of the posteiror chamber
19
Q
This is the space between anterior and posterior zonules
A
Zonular compartment of the posterior chamber
20
Q
This is the space between posterior pigment epithelium of iris and anterior zonules
A
Pre zonular compartment of the posterior chamber
21
Q
Posterior (central) boundary of the anterior chamber
A
Pupil and capsule of lens
22
Q
Posteiror (peripheral ) boundary of the anterior chamber
A
Anterior border layer of the iris
23
Q
Anterior boundary of the anterior chamber
A
Corneal endothelium
24
Q
Peripheral boundary of the anterior chamber
A
Iridocorneal angle
25
Volume of aqueous in the anterior chamber
200-250 microliters
26
Depth of the anterior chamber
3.6mm to 2.7mm with age
27
Angle formed in the periphery of the anterior chamber by the fusing of the ideal tunic and fibrous Tunic
Iridocorneal angle (anterior chamber angle)
The longitudinal bundle of the ciliary muscle (Bruch's) attached to the scleral spur
28
Iridocorneal angle from inferior to superior
- iris root
- ciliary body band
- scleral spur
- trabecular meshwork
- schwalbes line
I cant see this shit
29
Anterior chamber volume
200-250
30
Posterior chamber volume
50-65
31
Aqueous humor is secreted at a rate of _________
2.5ul per minute
32
Volume of aqueous compartment turned over every ____________
100 minutes
33
What terminates at the schwalbes line
Decemets membrane
34
Inserts into the anterior face of the ciliary body
Iris root
35
Thinnest part of iris
Iris root
36
What is thin and susceptible to traumatic injury (iridodialysis)
Iris root
37
Widest band visible in the iridocorneal angle
Ciliary body band
38
What color does the ciliary body band appear
Brownish/grey
39
What's the difference between the epithelium of the ciliary body in the posteiror chamber vs the anterior chamber
The ciliary body in the anterior chamber has no epithelium lining. Aqueous cannot pass through here
40
Internal projection of the sclera
Scleral spur
41
Provides attachment for longitudinal bundle of ciliary muscle and provides attachment for base of trabecular meshwork
Scleral spur
42
How might contraction or relaxation of the ciliary muscle affect aqueous outflow
Scleral spur pulled during accommodation, effects flow of aqueous, IOP fluctuates
43
Sits within the interval scleral sulcus above the scleral spur
Trabecular meshwork
44
The filtration apparatus that proves the main resistance to keep the eye pressurized
Trabecular meshwork
45
90% of aqueous humor outflow
Trabecular meshwork
46
What is the gate keeper to Schlemm's Canal
Trabecular meshwork
47
Resistance to aqueous outflow becomes too high in
POAG
48
Too much resistance does what to IOP
Increases
49
Peripheral termination of Descemet's membrane
Schwalbes line
50
Most superior structure in the iridocorneal angle
Schwalbes line
51
What color does schwalbes line appear
Glossy whitish color
52
Where does the other 10% of aqueous humor leave the iridocorneal angle
Iris root/ciliary body band
53
If outflow of the aqueous humor is impeded
The pressure in the eye will go up and may damage retinal ganglion cells (glaucoma)
54
What can cause enhanced resistance to aqueous humor drainage through the trabecular meshwork
- build up of pigment or other things
- chronic corticosteroid use
- elevated episcleral venous pressure
- narrow angles
- pupillary dilation
- relative pupillary block
- peripheral anterior synechiae
- POAG
55
Slit lamp and the iridocorneal angle
You cant see the anatomy of the iridocorneal angle with a slit lamp alone, but you can assess peripheral depth of anterior chamber using van Herrick technique
56
What does a grade one VH mean
Closed angle (1:<1/4)
57
What does a VH grade 4 mean
Open angle (1:1)
58
Can van herrick replace gonioscopy?
No
59
What side of the eye do you assess van herrick technique
Usually temporally
60
Other than van herrick what else can you use to check angle
Goniolens
61
What structure must remain visible when checking angle
Trabecular meshwork
62
Why cant aqueous pass through iris
It's a 1 way valve
63
Angle closure caused by relative pupillary block
Resistance to movement of aqueous humor from the posterior chamber to the anterior chamber can cause pressure in PC to elevate and push the iris root to impede flow through the TM
64
What is the difference between laser iridotomy and surgical iridectomy
Iridotomy the laser just puts a small hole in the iris
Iridectomy takes out a whole wedge
65
Posterior synechiae
Iris is stuck to lens, adhesion can block flow. Need to be broken with atropine
66
Dark room provocative test
Checking angles in dim light so iris bunches up, this can block angle so you wanna check it
67
Iris cyst
Can block flow
68
Neovascularization of TM
Can cause increased resistance
69
Peripheral anterior synechia
Iris to cornea
70
Basal infoldings
- Na/K ATPase pumps
- aqueous pumps
- increased surface area for secretion
71
What is aqueous humor derived from
Ultrafilatrate of blood
72
Aqueous contains ______% of protein content of blood plasma
Less than 1%
73
Why does aqueous contain so little protein
Protein causes light scatter and would be detrminetnal to the eyes optical system
74
What are the two steps in formation of aqueous humor
1. Ciliary body microvasculature: elaboration of a plasma filtrate
2. Ciliary epithelium: formation of aqueous humor from plasma filtrate
75
What forms the major arterial circle of hte iris
Long posterior ciliary arteries and anterior ciliary arteries
76
Anterior arterioles supply what
Stroma
77
Posterior arterioles supply what
Ciliary muscle
78
What capillaries are fenestrated?
Caps from the anterior arterioles are fenestrated and leak plasma protein, fluids, and ions into the ciliary stroma. They are leaky because the endothelial cells lining the caps lack tight junctions
Caps from the posterior arterioles are non-fenestrated
79
What is the first step in aqueous production
Fenestrated caps in the anteiror arterioles leak stuff into the stroma
80
How do ions flow from into the stroma
From pigmented into non pigmented into stroma into PC.
Tight junctions prevent aqueous from going back in
81
What is the blood aqueous barrier
Tight junctions in the ciliary epithelium don't allow aqueous to come back in
82
What is the second step of aqueous production
Formation of aqueous humor from plasma filtrate
-ions from filtrate actively transported into the pigmented ciliary epithelium and move to the nonpigmented ciliary epithelium via gap junctions
Ions pumped into intercellular clefts between cells of the NPE
Presence of these ions in the cleft draws water out into the cleft
83
What is the blood aqueous barrier
Tight junctions between the NPE cells restrict flow towards the PC
84
What happens in the blood aqueous barrier breaks down
Proteins from stroma into PC. Inflammatory cells
85
What happens if gap junction are unable to communicate with adjacent cells
Decrease production, IOP decreases. Uveitis usually has a drop in IOP
86
What is found along the basal infoldings of the ciliary epithelium
Na-K ATPase and carbonic anhydrase
87
What is a method used to decrease aqueous production in glaucoma therapy
Carbonic anhydrase inhibition
88
Protein content in the aqueous humor of PC
0%
89
Protein content in the aqueous humor of the AC is
1%
90
What chamber actually has protein in the aqueous
AC
91
Convective flow current
Aqueous enters the anterior chamber and immediately rises near the iris due to the warm iris vasculature and falls near the cooler corneal endothelium
92
Pigment from iris pigment epithelium deposits in a ________ on the corneal endothelium
Vertical line
93
What is the vertical line that falls on the corneal endothelium called
Kruckenbergs spindle
94
What does the vertical spindle fall that way
Caused by settling of pigment as it falls on the cooler corneal endothelium
95
What is the blood aqueous barrier
Tight junctions between non pigmented ciliary epithelium
96
Where else does the blood aqueous barrier exist
Iris
97
What can peripheral iridotomy result in
Cataract
98
What are the two pathways of egression of aqueous outflow
Conventional (TM) or unconventional (uveosleral)
99
What path does 90% of the aqueous outflow take
trabecular meshwork
100
Flow through the meshwork is ____ dependent
Pressure
-must be high enough to push through trabecular meshwork to reach schlemms canal. If resistance is too high, IOP elevates, glaucaom
101
Where does the TM sit
Internal scleral sulcus
102
Where does the base of the TM attach
Scleral spur
103
Where does the apex sit of the TM
Schwalbes line
104
What extends into the TM
Longitudinal fibers of ciliary muscle
105
Self cleaning filter containing phagocytes
TM
106
What is in the apex of the TM
Stem cell niche
107
What is the non filtering portion of the TM
Apex
Because it is above schlemms canal
108
What portion of the TM filters
Base
109
What is the TM divided into
Uveal and corneoscleral meshwork
110
Iris process
Reach up into and merge with the trabecular beams of the uveal meshwork. Iris processes do not impede aqueous outflow
111
What part of the TM faces the AC
Uveal meshwork
112
Netlike structure with openings, beams composed of collagen and elastin surrounded by endothelial cells that are continuous with corneal endothelium
Uveal meshwork
| -very versatile, maintain TM
113
Deep to uveal meshwork
Corneoscleral meshwork
114
Flat perforated sheets, channels become progressively smaller deeper into the tissue
Corneoscleral meshwork
115
Innerwall of schlemms canal
Juxtacanaliuclar connective tissue
116
Situated between corneoscleral meshwork and inner wall endothelium of schlemms canal
Juxtacanalicular connective tissue
117
Amorphous, contains fibroblasts cells, extracellular matric material, and elastic-like fibers
Juxtacanalicular CT
118
Provides bulk of aqueous humor resistance
Juxtacanalicular CT
119
Where is schlemms canal located
Outermost part of internal scleral sulcus
120
Outer wall of schlemms canal sontains channels that drain through the _______ via venous plexi
Scleral
121
During accommodation, the scleral spur
Moves posteriorly and enhances flow across the entire TM by opening up flow channels which increases the effective filtration area
122
Plaque
Increased IOP
123
Uveoscleral outflow during accommodation
Decreased outflow
124
Pressure and uveoscleral outflow pathway
Pressure independent
125
Pathway of uveoscleral outflow
- aqueous humor enters ciliary body band and iris root
- passes between the bundles of muscle fibers of the ciliary body to enter hte supracilaory space
- from the supraciloary space the aqueous is pumped through the sclera and to the episclera
126
Drugs to suppress aqueous humor formation
-carbonic anhydrase inhibitors (diamox), alphagan A2 agonist
127
Drugs to enhance outflow through trabecular pathway
ROCK inhibitors
| Pilocarpine
128
Drugs that enhance outflow through the uveoscleral pathway
Prostaglandin analogs (Xalatan)
