Uvea and iridocorneal angle

Question 1

Identify the 3 structures that make up the uvea and their functions

Answer 1

Structures: Iris, Choroid, Ciliary body
Functions: Nourish interior (O2& glucose), Production & outflow of AqH, Immune responses, Lens accommodation

Question 2

Understand the process of aqueous humor production and outflow

Answer 2

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

Question 3

Understand the anatomy of the ICA and the implications of angle abnormalities

Answer 3

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

Question 4

uvea

Answer 4

Middle part of the eye; contains the choroid, ciliary body, and iris

Question 5

tapetum

Answer 5

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

Question 6

corpora nigra

Answer 6

granula iridica; predominantly seen in grazing animals, believed to act as a shade

Question 7

pressure

Answer 7

build up due to collapsed ICA leads glaucoma

Question 8

aqueous humor

Answer 8

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

Question 9

iridocorneal angle

Answer 9

Boundary between cornea and iris
Where AqH leaves the eye
If it can’t, pressure increases leading to glaucoma
Glaucoma – causes collapse of angle

Question 10

outflow

Answer 10

important to prevent build up of pressure behind the eye (aqueous humor)

Question 11

pectinate ligament

Answer 11

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).

Question 12

iris

Answer 12

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

Question 13

blood ocular barriers

Answer 13

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

Question 14

glaucoma

Answer 14

build up of pressure in the eye; collapsed ICA

Question 15

uveitis

Answer 15

inflammation of the uvea

Question 16

ciliary musculature

Answer 16

Facilitates AqH outflow
Contributes to lenticular accommodation
Spasms when there is intraocular inflammation

Question 17

ICA

Answer 17

iridocorneal angle

Question 18

choroid

Answer 18

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

Question 19

ciliary body

Answer 19

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

Question 20

intraocular

Answer 20

within the eye

Question 21

pupil

Answer 21

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