Uvea and iridocorneal angle Flashcards
Identify the 3 structures that make up the uvea and their functions
Structures: Iris, Choroid, Ciliary body
Functions: Nourish interior (O2& glucose), Production & outflow of AqH, Immune responses, Lens accommodation
Understand the process of aqueous humor production and outflow
Active production by selective transport by carbonic anhydrase and Na+K+ATPase; Passive diffusion and ultrafiltration of blood plasma
AqH returns to systemic vascular system; Majority thru conventional pathway; Alternative uveoscleral pathway
Understand the anatomy of the ICA and the implications of angle abnormalities
Boundary between cornea and iris
Some ciliary body muscle fibers insert here, when ciliary body contracts ICA is opened and outflow is increased
Where AqH leaves the eye
If it can’t, pressure increases leading to glaucoma
Glaucoma – causes collapse of angle
uvea
Middle part of the eye; contains the choroid, ciliary body, and iris
tapetum
Doubles probability of absorbance
Pigs don’t have one
Dogs, cats, horses, cows, goats do
2 types
o Cellular – most carnivores, iridocytes form rodlets
with increased levels of zinc and riboflavin
o Acellular (fibrous) – herbivores, highly organized
collagen, “stars of Winslow” –capillaries see in tapetum
corpora nigra
granula iridica; predominantly seen in grazing animals, believed to act as a shade
pressure
build up due to collapsed ICA leads glaucoma
aqueous humor
fills the anterior and posterior chamber of the eye; Supplies nutrition to lens and cornea; Waste sink to same; Balance btw production and outflow maintains IOP; Normally clear medium for light refraction
iridocorneal angle
Boundary between cornea and iris
Where AqH leaves the eye
If it can’t, pressure increases leading to glaucoma
Glaucoma – causes collapse of angle
outflow
important to prevent build up of pressure behind the eye (aqueous humor)
pectinate ligament
the network of fibers (pectinate ligaments) at the iridocorneal angle between the anterior chamber of the eye and the venous sinus of the sclera
it contains spaces between the fibers that are involved in drainage of the aqueous humor and is composed of two portions: the corneoscleral part (the part attached to the sclera) and the uveal part (the part attached to the iris).
iris
anterior portion of the uvea; Forms diaphragm in front to lens; Central aperture = pupil which controls amount of light entering eye; Enhances visual resolution
2 zones
Pupillary zone; Ciliary zone
blood ocular barriers
Blood - aqueous barrier
Tight junctions between cells of ciliary epithelia and vascular endothelium
Blood - retinal barrier
Retinal pigment epithelium and capillaries
Maintains ocular privilege, limits damage to ocular structures by systemic conditions
glaucoma
build up of pressure in the eye; collapsed ICA
uveitis
inflammation of the uvea
ciliary musculature
Facilitates AqH outflow
Contributes to lenticular accommodation
Spasms when there is intraocular inflammation
ICA
iridocorneal angle
choroid
Posterior portion of uvea
Lies between sclera and retina
Continuous with ciliary body
Main source of O2 and nutrition for outer retina
Multi-layered structure: Suprachoroidea-> Large vessel layer-> Medium-sized vessel layer-> Tapetum-> Choriocapillaris
Heavily pigmented
Site of alternative AqH outflow
ciliary body
Middle portion; Produces aqueous humor and serves as anchor for fibers that suspend the lens
2 portions: Pars plicata (ciliary processes); Pars plana (flattened posterior zone)
Functions: Blood aqueous barrier (CP); Produces AqH (CP); Involved in AqH drainage (ICA); Generates IOP; May provide for lenticular accommodation
intraocular
within the eye
pupil
central aperture in the iris; controls the amount of light coming into the eye
birds: have some striated muscle which allows them to have some control
most other animals, smooth muscle and under autonomic control
