Iris Ugh

Question 1

Average diameter of the iris?

Answer 1

12mm

Question 2

How thick is the iris root?

Answer 2

500 microns (thinnest point)

Question 3

Pupil center is what to iris center?

Answer 3

Slightly nasal and inferior

Question 4

What are the four layers of the iris?

Answer 4

• anterior border layer
• stroma and sphincter muscle
• anterior epithelium and dilator muscle
• posterior epithelium

Question 5

Which layer of the iris is the dilator muscle?

Answer 5

Anterior epithelium

Question 6

Is the anterior border layer separate from the stroma?

Answer 6

Nope

Question 7

What kind of cells are in the anterior border layer?

Answer 7

Fibroblasts and pigmented melanocytes

Question 8

Anterior iris synechia at iris periphery can adhere to what?

Answer 8

Corneal endothelium or trabecular mesh work

Question 9

What kind of cells does the iris stroma consist of? How are the fibrils arranged?

Answer 9

• pigmented AND non pigmented cells!
• collagen fibrils in radial columns
• extensive ground substance

Question 10

What muscle is in the stroma?q

Answer 10

Sphincter muscle

Question 11

What does the sphincter muscle do?

Answer 11

• joined by tight junctions to constrict for miosis
• anchored to stroma
• innervates by parasympathetic system

Question 12

The end of what muscle indicates the pupillary area?

Answer 12

The end of the constrictor muscle

Question 13

The apical portion of the anterior epithelium is made of what and which direction does it face?

Answer 13

• pigmented epithelium with tight junctions

- faces back

Question 14

The basal portion of anterior epithelium is composed of what? Faces what directions?

Answer 14

• smooth muscle processes which extend into the stroma

- faces front

Question 15

Which layer is the dilator muscle in?

Answer 15

Anterior epithelium

Question 16

What does the dilator muscle do?

Answer 16

-cause mydriasis and is sympathetically innervates

Question 17

What kind of cells are in the posterior epithelium?

Answer 17

-single layer of heavily pigmented columnar cells joined by tight junctions

Question 18

Which epithelium layer has pigment that comes off when it rubs the lens?

Answer 18

Posterior epithelium

Question 19

Where is the major circle of the iris? Talk about the collagen too

Answer 19

• located in the ciliary body
• follow radial course
• thick walled blood vessels-collagen fibrils encircling vessels are continuous with the collagen network of the stroma

Question 20

Where is the minor circle of the iris?

Answer 20

• at the junction of ciliary and pupillary portions

- located within the iris stroma

Question 21

Which circle is non fenestrated and forms the blood aqueous barrier?

Answer 21

-mini circle of the iris

Question 22

Where is the major arterial circle of the iris located?

Answer 22

In the ciliary body

Question 23

You fire a diode laser shot at the iris and see black charring on the surface. Which layer was affected?

Answer 23

Anterior border layer

Question 24

You fire a YAG laser shot at the iris and see pigment coming out of the pupil. What layer cause this?

Answer 24

Posterior epithelium

Question 25

You fire an argon laser shot at the iris and see contraction around the spot which layer was affected?

Answer 25

Stroma

Question 26

You fire an infrared diode laser at the iris and notice radial movement from the pupil to the limbus. Which layer was this?

Answer 26

Anterior epithelium and dilator muscle

Question 27

How many times per second does the eye constrict/dilate?

Answer 27

2 times per second

Question 28

What are rhythmic oscillations called?

Answer 28

Hippus

Question 29

Increased illumination causes what effect with hippus

Answer 29

Larger and more rapid in increased illumination

Question 30

What is iridodialysis

Answer 30

- root tears away from the ciliary body | - blood may hemorrhage into anterior or posterior chambers to create hyphema

Question 31

Iris color depends on what?

Answer 31

- number AND type of melanin granules within the melanocytes. - IT DOES NOT DEPEND ON THE NUMBER OF MELANOCYTES BECAUSE THAT IS CONSTANT

Question 32

In Horner' syndrome, which pupil has a lighter iris?

Answer 32

The smaller pupil

Question 33

What is pigmentary dispersion syndrome?

Answer 33

- pigment shed from posterior iris surface - depostied on iris, lens, corneal epithelium or mesh work - can cause transillumination defects

Question 34

What is anisocoria

Answer 34

- detectable difference between pupil diameters | - less than 0.4mm is normal

Question 35

Name the primary functions of the iris

Answer 35

- regulate retinal illumination - regulate glare - regulate optical aberrations - regulate depth of focus - nonverbal communication and social signaling - attraction/mate selection

Question 36

What size pupil increases depth of focus?

Answer 36

Smaller