B12 Flashcards
For someone with glaucoma, is the AH flow in and out equal?
No
Is the uveoscleral pathway the minor or major route /pathway in AH outflow?
Minor
Describe how AH flows in the uveoscleral pathway
AH enters the connective tissue between the ciliary muscle bundles, through the suprachoroidal space, and out through the sclera
Is the uveoscleral outflow affected by IOP?
Nope
The outflow rate through the uveoscleral route tends to ____ with age
Decrease
What are the 3 layers of the TM?
- juxtancanalicular
- corneaoscleral
- uveal
The corneoscleral pathway is considered the ____ route
Major
Describe the flow of AH in the corneoscleral pathway
AH passes through the TM, across SC, into its lumen
and into draining collector channels, aqueous veins and episcleral veins
Is the corneoscleral pathway IOP independent or dependent?
dependent
An acute rise in EVP results in a ___ ratio of increase IOP
1:1
When the aqueous outflow pump receives power from transient increases in IOP such as occur in systole of the cardiac cycle during blinking and during eye movement
Pumping model
In the corneoscleral pathway an increase of IOP causes drainage decrease or increase?
Increase
What will make schlemm’s canal collapse on itself and obstruct into the venous system?
Constant, very high IOP
What 2 fluid compartments is the TM suspended between?
And are these at the same or different pressures?
Anterior chamber and schlemms canal
They have different pressures
What 5 things can cause AH outflow obstruction through occlusive angles?
- severe diabetes
- uveitis
- hyphema
- pseudoexfoliative glaucoma
- pigment dispersion glaucoma
In humans, ___% of the resistance to the AH outflow is localized to the TM, and ___% occurs beyond schlemm’s canal
75% to TM
25% to SC
Can an injury to the TM cause an obstruction of AH outflow?
It sure can
What are the 3 long term influences on IOP?
- genetics
- gender
- refractive error
What are the 6 short term influences on IOP?
- diurnal
- postural variation
- lid and eye movement
- systemic conditions
- environmental conditions
- food and drugs
T/F: IOP is under hereditary influence
True
Are IOP’s different between men and women in the ages of 20-40?
Nope, they are equal
In older age groups, do men or women have a increase in mean IOP?
Women
Myopic people have a ____ incidence of open angle glaucoma
Higher
T/F: there is a positive correlation between IOP and both axial length and increasing degrees of myopia
True
Does IOP change throughout the day?
Yep
When is the peak of IOP?
In the morning
T/F: IOP decreases changing from sitting to the supine position
False, it increases
Patient with systemic hypertension will have a greater IOP increases after ___ min in supine
15 minutes
Does blinking raise IOP?
Yes, by 10mmHg
How much does hard lid squeezing raise IOP?
As much as 90mmHg
In what gaze is there in increase in IOP in normal individuals?
Up gaze
Thicker corneas cause artificially ____ readings
High
Thinner corneas cause artificially ___ readings
Low
T/F: patients with HIV have lower than normal mean IOPs
True
Are IOPs increased or decreased during pregnancy?
Decreased
Does exposure to cold air increase or decrease IOP? And why
Decreases, because episcleral venous pressure is decreased
Does reduced gravity cause an increase or decrease in IOP?
Increase
Does alcohol increase or decrease IOP?
Decrease
Does caffeine cause an increase or decrease in IOP?
Slight transient rise
Does smoking increase or decrease your IOP?
Increase
Do heroin and marijuana increase or decrease IOP?
Decrease
Does LSD increase or decrease IOP?
Increase
Do corticosteroids increase or decrease IOP?
Increase
What it the major pathway of AH outflow?
Corneoscleral pathway
What AH pathway is IOP independent?
Uveoscleral pathway
Does AH pass through the SC in the uveoscleral pathway?
No
An acture increase in EVP by 4mmHg will theoretically cause an increase in IOP by?
4mmHg
T/F: thicker cornea can cause an artificially high IOP reading
True
What is the largest organ of the eye?
Vitreous
The vitreous transmits ____ of light
90%
The vitreous is located between the ___ and the _____
Crystalline lens and the retina
What are the 3 zones of the vitreous?
Outermost zone (vitreous cortex) Center zone (cloquets canal) Intermediate zone (inner to the cortex and surrounds the center canal)
The vitreous is attached to what part of the retina?
Inner limiting membrane
What attaches the vitreous to the ILM?
Anchoring fibrils and the membrane limitans interna (MLI)
What 3 things is the MLI composed of?
- fusing point of the anchoring fibrils
- lamina densa
- lamina Lucida
The vitreous base is located at the ____
Ora serrata
The vitreous base is ___mm broad annular region
1.5
The vitreous base is attached to the ___ and the ____
Nonpigmented epithelium of the ciliary body and the internal limiting membrane of the peripheral retina
What is the strongest attachment to the vitreous?
Vitreous base
Does the vitreous base decline with age?
No
A vitreous attachment that is between the posterior surface and the anterior face of the vitreous
Wiegers ligament
Does the wiegers ligament decline with aging?
Yes
The vitreous attached around the edge of the optic disc?
Peripapillary adhesion
Does wiegers ligament have a firm or medium attachment?
Firm
Does the peripapillary adhesion have a firm or medium vitreal attachment?
Medium attachment