Iris

Question 1

What part of the eye is the iris located in? What is its diameter? What are its characteristics? What other structures does it include?

Answer 1

Vascular Tunic or Uveal Tract (pigmented and vascular)
12mm

Iris
Ciliary Body
Choroid (continuous with ciliary body)

Question 2

What is the primary and secondary function of the iris?

Answer 2

Primary- functions as a diaphragm, pupil at the center, regulates the amount of light entering the eye

Secondary- defense against penetrating injury

Question 3

What is the difference between scotopic and photopic conditions?

Answer 3

Scotopic- dark conditions, pupils open

Photopic- light conditions, pupils become smaller

Question 4

What is Miosis and Mydriasis?

Answer 4

Miosis makes pupils smaller

Mydriasis makes pupils bigger

Question 5

What is the collarette?

Answer 5

Area where dilator muscle and sphincter overlap
Thickest area of iris
Divides iris into pupillary and ciliary zone

Question 6

Describe hippus and how it relates to the pupil?

Answer 6

Normal rhythmic fluctuation of pupil dilation/contraction
Regulated by autonomic NS

Question 7

What are crypts on the iris?

Answer 7

Depressions
Most anterior part of the iris (anterior border layer) are missing
Aqueous escapes

Question 8

What is the pupillary ruff?

Answer 8

Region closest to the pupil where epithelial layers of iris meet
Posterior iris loops onto surface

Appears brown in everyone

Question 9

What is the iris root?

Answer 9

Region where iris and ciliary body connects

Question 10

How are collagen fibrils arranged on the iris?

Answer 10

Radial arrangement

Question 11

What is the difference between nevus and freckles in the iris?

Answer 11

Nevus- cluster of melanocytes (cancer causing)

Freckle- accumulation of melanin

Question 12

What is a contraction furrow?

Answer 12

Indicates the movement of the iris

Question 13

Describe the Iris-lens channel.

Answer 13

Region where iris interacts with lens, slightly anterior to the iris