Choriod Flashcards
What structures are involved in the uveal tract?
the choroid, iris, and ciliary body
what tunic is the uveal tract considered
the vascular layer or tunic
what is considered the anterior uvea
the ciliary body and iris
what is considered the posterior uvea
the choriod
what 3 places is the uvea attached to the sclera
scleral spur, vortex veins, and the optic nerve
how is the uvea lined
by two continuous layers derived from the neuroectoderm
what is the uvea mainly composed of
melanocytes, blood vessels and connective tissue
what is the primary function of the choroid
to nourish the outer layers of the retina - also heat exchange from the retina due to the high volume of blood
how much blood does the choroid account for flowing through the eye
85%
what 3 layers is the choroid divided into
Bruch’s membrane, capillary layer, and vessel layer
how many layers is Bruch’s membrane
5 layers: basement membrane (choriocapillaries), outer collagen, elastic fibers, inner collagen, basement membrane (RPE)
What is the function of Bruch’s membrane
passage of fluid from the choriocapillaries to the retina
where does drusen appear
between the basement membrane of the RPE and inner collagen layer
Does Bruch’s membrane have innervation
No
which choriod layer will thicken throughout life
Bruch’s membrane- in the macula
what is the choriocapillary layer
a single layer composed of wide-bore capillaries with sac-like dilations
are the anterior capillaries of the choriocapillaries fenestrated?
yes, for production of aqueous humor
are the posterior capillaries of the choriocapillaries fenestrated
no, (near the ciliary muscle)
where are the choriocapillaries the sole provider of nutrients to
the macula
what type of network is near the macula
a lobulated network
are the anastomoses between the lobules of the choriocapillaries
no, if one lobule is damages or destroyed the other lobules will remain working
what layer of the choroid is the most external
the vessel layer
what is Sattler’s layer
the inner layer of medium sized vessels
what is Haller’s layer
the outer layer of large vessels
what arteries feed the vessel layer
branches from the short posterior ciliary arteries (10-20)
what is the choroidal stroma
a sparse region mostly occupied by blood vessels
what is the suprachoroid lamina
thin pigmented sheets of connective tissue that travel across the suprachoroidal space
what is the suprachoroial space
a potential space between the choriod and sclera where long and short posterior ciliary arteries and nerves travel
what is unique about the arterial and venus system of the choroid
they do not parallel each other
what veins drain the choriod
the vortex veins
what innervates the choroid
long and short posterior ciliary nerves
what signal do the long posterior ciliary nerves carry
sensory fibers from the cornea, iris, ciliary muscle
what type of nerves come from the superior cervical ganglion
Long posterior ciliary postganglionic sympathetic fibers - go to the dilator muscle of the iris
where do the long posterior ciliary nerves enter and travel in the eye
pierce the sclera about 3-4mm from the optic nerve and travel in the suprachoroidal space
where do the long ciliary nerves arise from
the nasociliary branch of the ophthalmic division of the trigeminal nerve (CN 5)
why is the blood flow so high in the choroid
there is low resistance of the choroidal capillaries, they are wider and broader than retinal capillaries
what is the oxygen content for the veins in the choroid
about 95% to that of the arteries
why might the choroid have such a low oxygen content
it suggests that it may play a role in heat exchange from the retina
Is the choroidal vasculature autoregulated or neuroregulated
neuroregulated
