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49 Cards in this Set
- Front
- Back
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what systemic/topical drug vasoconstrictors have an effect on retinal vasculature?
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none
retina is resistant to topical and systemic drugs |
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what is the effect of high oxygen concentrations on ocular blood flow?
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vasoconstriction
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what is the effect of high carbon dioxide concentrations on ocular blood flow?
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vasodilation
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what is the effect of pure oxygen on ocular blood flow?
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constriction of vessels
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what is the effect of pure oxygen on the choroid?
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no effect
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why are premature babies susceptible to retinopathy of prematurity?
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high oxygen environments cause vasoconstriction in infants, which impair development of vessels in the eyes of infants
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what two symptoms are expected in infants with retinopathy of prematurity?
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-limited visual fields
-retinal detachment likely |
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what prevents the effect of systemic and topical drugs on the retina?
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blood-retina barrier
-prevents effect of drugs |
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what are pericytes?
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cells present on almost all capillaries, arterioles and venules
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where is the highest concentration of pericytes?
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densest on retinal capillaries
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what are four functions of the pericytes?
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-Angiogenesis
-Stabilization of vessels -Contractile properties (regulate blood flow) -Maintenance of BBB and BRB |
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A decrease/increase of pericyte density, will cause an increase in retinopahy.
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decrease
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What effect does a loss of pericytes have on stabilization of vessels?
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unstabilized vessels are not stable, and the walls are weak.
this causes distention --> microaneurysms |
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what effect does a loss of pericytes have on the maintenance of BBB and BRB?
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hemorrhages
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true or false
angle closure glaucoma can cause a spike in IOP |
true
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how does dry AMD become neovascular (wet)?
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-blood flow is reduced to the macula
-RPE becomes less functional -choriocapillaris is no longer contained -choroidal neovascularization into the retina causes leakage |
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what are the two major capillary networks that supply the inner retina?
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ganglion cell layer (inner)
inner nuclear layer (outer) |
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what effect does epinephrine have on uveal tract blood flow?
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reduces blood flow in the uveal tract
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what effect does angiotensin have on posterior ciliary arteries?
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promotes contraction of posterior ciliary arteries
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epinephrine and angiotensin are vasoconstrictors/vasodilators
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vasoconstrictors
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what kinds of capillaries are found in the eye?
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continuous, fenestrated
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what type of capillary is found in the retina?
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continuous
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what type of capillary is found in the choroid?
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fenestrated
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what are two blood ocular barriers are found in the eye?
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blood retina barrier
blood aqueous barrier |
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what makes up the blood retina barrier?
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tight junctions in capillaries and between RPE cells
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what makes up the blood aqueous barrier?
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-tight junctions of NPCE
-tight junctions between endothelial cells of iris capillaries |
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what is fluorescein angiography helpful clinically?
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assess blood flow in the retina
-good in diabetes, vein occlusions, AMD |
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what is the first part of the eye that dye can be seen in when doing fluorescein angiography?
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choroidal phase
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where is the dye injected when doing fluorescein angiography?
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anticubital vein
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what are the stages of an angiogram?
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1. choroidal phase
2. arterial phase 3. arteriovenous phase 4. venous phase |
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what is the retinal circulation time?
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3-5sec
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why is the fovea so dark?
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1. foveal avascular zone
2. increased xanthophyll blocks fluorescence 3. RPE cells are larger and contain more pigment |
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true or false
choroidal blood flow helps to protect the eye form thermal damage |
true
blood flow, shunts away excess heat |
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why don't autonomic nerves supply the retina?
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don't want to flood delicate BV with blood
-good during stress situations, when increased blood flow is usually seen due to SNS stimulation |
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what percentage of oxygen and glucose does the choroid supply the retina?
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65% oxygen
75% glucose |
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what test can be used to asses damage to small vessels by diabetes?
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fluorescein angiography
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what are blood ocular barriers impermeable to?
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everything
-glucose, O2, CO2, etc. |
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where is there an interruption in the blood retina barrier?
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at optic disc
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what does Indocyanin green assess? what disease?
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assess choroidal circulation
AMD |
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Pilocarpine increases/decreases blood flow.
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increases
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ACh dilates/constricts uveal blood flows.
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dilates
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Angiotensin promotes contraction/dilation of posterior ciliary arteries.
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contraction.
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A patient comes in with ROP, what is a likely symptom of of this infant?
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-limited visual field
-retinal detachment likely |
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What contributes to the cause of ROP?
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infants being exposed to a high oxygen environment, high oxygen concentrations cause vasoconstriction of vessels in the eyes, and impair development of vessels and cause dysfunction of vessels
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Where in the body can you find the greatest density of pericytes?
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On retinal capillaries
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A loss of pericytes have what effect on previously stabilized vessels
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cause microaneurysms
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Blood flow to the macula and choroidal blood flow, decreases with ____.
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age
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How does damage occur with angle closure glaucoma.
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High IOP, doesn't allow blood to perfuse the eye
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Where are capillary free zones in the retina? (2)
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around arterioles
fovea |
