Flashcards in Retinal Blood Flow Deck (63):
The central retinal artery enters the optic nerve about ______mm behind the globe
10 - 12mm
The CRA supplies the ______
optic nerve and pia mater
What nerve plexus surrounds the CRA?
the nerve of Tiedemann
The central retinal circulation must be sparse and thin because _________
it is in front of the light path
What supplies the ganglion and bipolar cells?
What are the three aspects of the central retinal circulation?
A. CRA and CRV
C. Radial peripapillary circulation
The arteries and veins are within the ______ layer, while the capillary system forms a double layered system in most of the ______
The arteries and veins are within the *nerve fiber layer* layer, while the capillary system forms a double layered system in most of the *outer retina*
the Retinal Capillary Networks supply every part of the retina except for _____, _____, and ______
outer nuclear layer, photoreceptors and RPE
_____ serves an area between 10 and 20 degrees out from the macula. the first area where cotton wool spots appear and produces Bjerrum's scotomas in Glaucoma
Radial Peripapillary capillary system
What are the three aspects of the Choroidal Supply?
C. Cilioretinal artery
Cilioretinal arteries are only in ___% of the population
The anterior ciliary arteries follow the ______
2 anterior ciliary arteries arise from each of the rectus muscles except for the _______
lateral rectus muscle
The _______ supplies the oxygen and nutrient need of the outermost layers of the retina
What is the biggest and widest circulation in the body?
the _____ is the ONLY blood supply to the macula
Regarding speed, the CRC is ____ while the choroidal circulation is ____
CRC - slow
choroic - fast
What three layers does the choroid supply?
outer nuclear layer
The paraoptic region of the SPCA supplies the _____ while the distal region supplies the _____
paraoptic - Optic nerve head, peripapillary choroid, circule of Zinn/Haller
distal - Choroid
Each sector of the______ fit together like pieces of a jigsaw puzzle. each terminal choroidal arteriole supplies a ____ of the chorriocapillaris
Each sector of the *distal SPCA* fit together like pieces of a jigsaw puzzle. each terminal choroidal arteriole supplies a *lobule* of the chorriocapillaris
The branches of the ______ pierce the slcera lateral, medial, or infrequently superior to the optic nerve
To keep the choroid from scarring, if one _____ is destroyed by disease, the others will remain in tact
In the posterior pole, the _______ is arranged in a lobular fashion with alternating feeding arterioles and draining venules
The ______ lobule does not have its own blood supply
what is a watershed zone?
the border between the territories of distribution of any two end arteries. Poor vascularity.
The part of the optic nerve head that is located in the watershed zone is most vulnerable to _____
_______ is a loss of a lobule and occurs in a matter of minutes. Irreversible within hours to days.
The Optic Nerve Head Circulation (ONHC) is comprised from the _______
What are the four parts of the Optic Nerve Head circulation
1. Superficial nerve fiber layer
The pre-lamina is supplied by the ______
The _____ is a collagenous plate through which the nerve fibers run on their way out of the globe
Lamina (lamina cribosa)
The inner part of the retro-lamina is supplied by the _____ while the outer part is supplied by the ______
A ________ hemorrhage has a round appearance and is an indication the bleeding has occured in the deep capillary plexus. Cells are oriented _____ in the inner nuclear layer. usually binocular
Dot and blot hemorrhage. Cells oriented vertically.
A _______ hemorrhage has a wide, uneven appearance. Is an indication that bleeding has occured in the radial peripapillary capillaries. The cells here are oriented ______ in the nerve fiber layer. Usually binocular, but can be monocular in ________.
Flame-shaped hemorrhage. Cells oriented horizontally. Monocular in central retinal vein occlusion.
A _______ hemorrhage is in the viteous. Typically due to _______ which makes the borders indistinct.
Pre-retinal hemorrhage. Due to neovascularization.
A ________ hemorrhage arises from beneath the RPE. May be caused by ______ disease.
Subretinal hemorrhage. Can be caused by Coat's disease.
A ________ hemorrhage occurs beneath the RPE. A choroidal rather than retinal disease. Disappears with _____ filter on Opthalmoscope
Choroidal hemorrhage. Disappears with green filter.
_______ is a very rare condition where there is abnormal development in the blood vessels behind the retina. Blood leaks out of the retinal capillaries, which may _______. Usually in _____ and almost always unilateral.
Coat's disease. May detach the retina. Usually in males.
_______ is a result of ganglion cell death due to loss of oxygen. Cotton wool spots will appear. Immediate VA drop. Fast, painless, acute.
Central Retinal Artery Occlusion. Eventually revascularizes the retina, but the ONH is white... because the ganglion cells are dead.
________ involved a blockage of blood outflow. TMP increases and blood is pushed into the retina. VA may be 20/20 if _________.
Central Retinal Vein Occlusion. VA may be 20/20 if there is no fluid in the macula.
As resistance to flow increases, the perfusion pressure ______
Blood flow in a vessel occurs if there is a pressure gradient between two points within the vessel
What is autoregulation?
the ability of a system to self-regulate its blood flow so that when the transmural pressure increases, the vessels will dilate to maintain the amount of blood flow.
Perfusion pressure is equal to ____ - _____
Pressure of artery - pressure of vein
Defective autoregulation leads to _____
The eye contains the only circulation system in the body that has an opposing pressure, the _____working against it
Transmural pressure is nearly zero in the eye because why?
the IOP and venous pressure are very similar
What is transmural pressure (TMP)?
the pressure inside the vein compared to the pressure outside the vein.
Every circulation system in the eye is autoregulated except for the _________
Lack of autoregulation in the choroid is compensated for by increased extraction of ______ with the slower blood flow as the IOP rises
Because of autoregulation, blood flow does not begin to fall until IOP reaches _______
True/False. venous pressure is always higher than the IOP.
FUCK YEEEEEAAAAAHHHHHHH VENOUS PRESSURE
the retinal venous pressure at the point where the central retinal vein leaves the eye is called the _____
In the retrolaminar space, the pressure is controlled by the _______
Spontanous venous pulsation is found in ____% of normal subjects and occurs in people with CSF pressure below ____ mmHG
90% of normal subjects. Occurs with CSF pressure below 190 mmHG
True/False. Normal SVP indicates that CSF pressure is normal.
FALSEEEEEE FUCK YOU FOR THINKING TRUE
What are the three types of open angle glaucoma?
1. Primary open angle glaucoma
2. Low tension glaucoma
3. Ocular hypertension
True/False. Elevated IOP is the cause of glaucoma
FALSE AS FUCK. IOP is simply a risk factor. You'd be better off using age as a predictor.
What is a transient ischemic attack?
Perfussion pressure decreases, resulting in a loss of blood flow, which results in a transient loss of vision
Transient Ischemic Attacks are generally caused by _______. If vision is lost, patient will probably experience _______
TIA generally caused by occlusion of carotid artery. If vision is lost, patient will probably have a stroke within the year
Pilots typically experience this due to the high amount of pressure they experience at high gravitational forces.
Transient ischemic attack. Loss of vision is described as a "curtain falling or rising"