Aqueous Humor

Question 2

What are the primary purposes of aqueous humor?

Answer 2

1) Maintain globe shape2) Nourishment & waste removal for the avascular cornea & lens.3) Source of antioxidants for corneal epithelium & lens4) Shock Absorber

Question 3

Refractive index of aqueous humor is…?

Answer 3

1.333

Question 4

Name the 3 vascular circles in the ciliary body.

Answer 4

Episcleral circle
intramuscular circle
major arterial circle (near iris root)

Question 5

Ciliary process is supplied by which 2 branches of the Major Arteriole Circle?

Answer 5

Anterior ciliary process arteriole

Posterior ciliary process arteriole

Question 6

Aqueous humor is secreted by which part of the eye?

Answer 6

ciliary epithelium of ciliary process

Question 7

Which two enzymes are involved in aqueous humor formation?

Answer 7

Na+ K+ ATPase

Carbonic Anhydrase

Question 8

Aqueous humor formation follows a _____ rhythm.It is greatest in which part of the day?

Answer 8

circadian.8am-noon, then afternoon, then least after midnight.

Question 9

What does carbonic anhydrase do?What do inhibitors of carbonic anhydrase do?

Answer 9

Turns carbonic acid into CO2 & H2O.Inhibitors can decrease aqueous humor production.

Question 10

Where is Na K ATPase found?

Answer 10

Bound to plasma membrane of non-pigmented epithelium of ciliary process.

Question 11

The Retinal Pigmented Epithelium and the Non-PIgmented Epithelium are joined by _____ which created a ______ between the blood vessels and aqueous humor.

Answer 11

tight junctions

blood aqueous barrier

Question 12

Which of these have fenestrated capillaries?
Which have nonfenestrasted?
ciliary process
iris
choroid
retina

Answer 12

Fenestrated:
ciliary process
choroid
Nonfenestrated:
iris
retina

Question 13

What are the primary and secondary pathways for aqueous humor outflow?

Answer 13

Primary: Trabecular meshwork routeSecondary: Uveoscleral/posterior route

Question 14

Inflow rate + outflow rate of aqueous humor = ?

Answer 14

Intraocular Pressure (IOP)

Question 15

A breakdown in the blood aqueous barrier increases _____.

Answer 15

IOP

Question 16

When aqueous humor inflow by ultrafiltration is suppressed it is called _____?Does this increase or decrease IOP?This inflammatory process also reduces or increases secretion of aqueous humor?

Answer 16

Pseudofacility.
Decrease IOP.
Reduces secretion.

Question 17

How does increased plasma components in anterior chamber and increased net inflow of fluid from blood to aqueous humor affect IOP?

Answer 17

Increases IOP

Question 18

Which factors increase IOP?Which factors decrease IOP?Increased ageWomen over 40WinterSupine PostureExerciseBlinking hardAlcohol, marijuana, heroinCaffeine, Tobacco

Answer 18

Increase:Increased
 age
Women over 40
Winter
Supine 
Posture
Blinking hard
Decrease:Exercise
Alcohol, marijuana, heroin

Question 19

Mean IOP magic # is _____?

Answer 19

21

Question 20

What is this equation called?
W + S = P x A + B
What is it used for?

Answer 20

Modified Imbert-Fick Law.Used to ascertain IOP.
W (external force)
A (area)
P (pressure inside sphere)
S (surface tension)
B (force req'd to bend cornea)

Question 21

What factors affect IOP measurements?

Answer 21

central corneal thickness
corneal curvatureage-related
corneal changes
biomechanics (rigidity, hydration, elasticity)

Question 22

The test performed to measure IOP is called ____?

Answer 22

tonometry

Question 23

The cornea’s physical properties can be described as _____?

Answer 23

visco-elastic

Question 24

The Pulsatile Ocular Blood Flow is a calculated value that represents ______ circulation?

Answer 24

Choroidal

Question 25

What are some reasons 24-hour IOP measurement would be helpful?

Answer 25

evaluate efficacy of drug testing,check for Normal Tension Glaucoma progression,identify IOP spikes over short & long term

Question 26

What are some methods of noninvasive and temporary 24-hour IOP measurement?

Answer 26

contact lensescontinuous applanation or indentation devices

Question 27

What are some methods of invasive and permanent 24-hour IOP measurement?

Answer 27

subconjunctivalante chamber implants in AC as IOL hap tics scleral buckle scleral fixated sensorpost chamber implants - choroidal

Question 28

80-90% of aqueous humor formation is done by which process?Which two processes form the rest of aqueous humor?

Answer 28

Secretion.Diffusion & Ultrafiltration.

Question 29

What are the 4 layers of the ciliary process?

Answer 29

CapillariesStromePigmented EpitheliaNonpigmented Epithelia

Question 30

What kind of outflow represents 70-95% of aqueous humor outflow?

Answer 30

Trabecular meshwork

Question 31

What kind of outflow represents 5-30% of aqueous humor outflow?

Answer 31

Uveoscleral

Question 32

What does Na K ATPase do in aqueous humor formation?What does this cause water to do?

Answer 32

Pushes Na+ ions into posterior chamber from ciliary process.Water follows it from the ciliary process cells, contributing to aqueous humor.

Question 33

Aqueous humor formation works against or with the concentration gradient?

Answer 33

Against.

Question 34

What are the 3 muscles in the ciliary body?

Answer 34

longitudinalcircularradial

Question 35

The Major Arterial Circle is made of paralimbal branches of which arteries?

Answer 35

Long Posterior Ciliary Arteries

Question 36

The longitudinal fibers attach the ciliary body to the _____?

Answer 36

limbus

Question 37

The radial muscles connect which two other muscles in the ciliary body?

Answer 37

longitudinal and circular muscles

Question 38

The circular muscles are found in which portions of the ciliary body?

Answer 38

anterior and inner portions

Question 39

Which time of the day is aqueous humor produced at about 2.97 µl/min.?

Answer 39

8am - noon

Question 40

Which time of the day is aqueous humor produced at about 1.28 µl/min.?

Answer 40

midnight - 6am

Question 41

Which time of the day is aqueous humor produced at about 2.68 µl/min.?

Answer 41

afternoon

Question 42

What is a pneumotonometer?

Answer 42

An instrument that blows a puff of air at the cornea to cause flattening and hence measure intraocular pressure. It is commonly used in tests for glaucoma.

Question 43

What is a Perkins tonometer?

Answer 43

A type of portable applanation tonometer

Question 44

What is applanation tonometry?

Answer 44

A method which measure IOP based on the force required to flatten (applanate) a constant area of the cornea.

Question 45

What are the conditions to Imbert-Fick law?

Answer 45

Must be perfect sphere, dry, infinitely thin | W= P1 x A

Question 46

Aqueous humor secreted by ciliary epithelium of ciliary process enters posterior chamber by what three ways? and describe them

Answer 46

Diffusion- lipid soluble substances Ultrafiltration- water and water soluble substances secretion - larger size substances of greater charge

Question 47

What is hypotony?

Answer 47

low intraocular pressure oftern related to chronic intracolular inflammation (uveitis) , wound leaks after eye surgery or retinal detachment

Question 48

pneumotonometer also gives____ amplitude and calculates _____ volume

Answer 48

pulse, pulse

Question 49

pneumotonometer measures ___ pulses and selects ___ best to calculate IOP and POBF

Answer 49

7 , 5

Question 50

T/F the IOP measurement you take inside , could be different then the one you take outside

Answer 50

T

Question 51

T/F the pneumotonometer has a large range of normality and the values are derived making numerous assumptions which makes accurate

Answer 51

F. it makes it INACCURATE