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Semester 2 Ocular > The Iris > Flashcards

The Iris Flashcards

1
Q

Look at objectives… 6 questions

A

slide 3

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2
Q

True/False: The size of the iris has great effect on the field of view of the eye.

A

False, has little effect on the field of view of the eye

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3
Q

True/False: The amount of light passing through the iris is proportional to its area.

A

True

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4
Q

Functions of Iris

A 
Regulates Retinal illumination
Regulates glare
Regulates Optical Aberrations
Regulates Depth of Focus
Provides nonverbal communications and social signaling
Attraction/ Mate selection
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5
Q

Avg diameter of Iris is what?

A

12 mm

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6
Q

Pupil center is slightly _____ and _______ to iris center.

A

nasal

inferior

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7
Q

Abnormally centered pupil is _________.

A

ectopic

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8
Q

Irregular or ectopic pupils ________ opical quality

A

degrade

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9
Q

______________ rests on anterior surface of lens.

A

Pupillary margin

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10
Q

______________ flows from posterior into anterior chamber through the pupil.

A

Aqueous humor

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11
Q

What are the 4 layers of the Iris?

A 
Anterior Border layer
Stroma and sphincter muscle
Anterior border layer
Stroma and sphincter muscle
Anterior epithelium and dilator muscle
Posterior epithelium
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12
Q

Which layer of iris is the dilator?

A

Anterior epithelium

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13
Q

Stroma consists of pigmented and nonpigmented cells, collagen fibrils, and extensive ________________.

A

ground substance

collagen fibrils are arranged in radial columns

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14
Q

Anterior border layer characteristics?

A

Not seperate layer from stroma
Fibroblasts and pigmented melanocytes
Can contain oval shaped iris crypts
Anterior iris synechia at iris periphery can adhere to the corneal endothelium or trabecular meshwork.

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15
Q

Sphincter muscle within stroma, what are some characteristics?

A 
Smooth muscle cells joined by tight junctions
.75 - 1 mm wide
Anchored to stroma
Constricts for miosis
Innervated by parasympathetic system
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16
Q

Anterior epithelium and dilator muscle has _________ which is pigmented epithelium joined by tight junctions

A

Apical portion

17
Q

Anterior epithelium and dilator muscle has _________ which is composed of smooth muscle processes which extend into stroma.

A

Basal portion

18
Q

Dilator causes mydriasis and is __________________ innervated.

A

sympathetically

19
Q

What is single layered, heavily pigmented, columnar cells joined by tight junctions.

A

Posterior Epithelium

20
Q

Where is the major circle of the Iris located?

A

Ciliary body

they are thick walled blood vessels

21
Q

Where is the minor circle of the iris?

A 
At junction of ciliary and pupillary portions
Inferior to the collarette
Located within the iris and stroma
Not fenestrated
Forms blood-aqueous barrier
22
Q

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

A

Posterior epithelium

23
Q

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

A

Anterior epithelium and dilator muscle. Specifically dilator muscle

24
Q

Iris dilates and constricts approx __ times per sec.

A

2 times per sec

25
Q

Rythmic oscillation of Iris is called ________.

A

Hippus

26
Q

Pupil size always has an implicit +/- _____

A

0.2 mm

27
Q

Absence of hippus can indicate problem with what?

A

innervation or damage to iris

28
Q

Where root tears away from the ciliary body.

A

Iridodialysis

May cause nerve and vessel damage

29
Q

What does eye color depend on?

A

Color depends on number and type of melanin granules within melanocytes. (Number of melanocytes are constant)

30
Q

This effects 6 out of 1,000 eyes.

A

heterochromia

31
Q

Anisocoria

A

Difference in iris

Difference of anything less than 4 mm is normal

Semester 2 Ocular (20 decks)

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