Iris Flashcards
1
Q
What muscle sis innervated by sympathtic efferent nerve fibers
A
Dilator pupillae muscle
2
Q
The _________ is the aperture stop of the optical system
A
Iris
3
Q
The effect of the iris on the field of view
A
Very little
4
Q
Where does the iris lay
A
In front of the lens and often touches it
5
Q
Entrance pupil of eye
A
Erect virtual image about 0.5mm in front of the real pupil and 1.13 times larger
6
Q
The amount of light passing through the pupil is proportional to what
A
It’s area
7
Q
Diameter squared
A
Amount of light
8
Q
Small aperture corneal inlay disadvantages
A
Halos
Change corneal curvature
Aberrations
Possible VF loss
9
Q
Functions of iris
A
- regulates retinal illumination
- regulates glare
- regulates optical aberrations
- regulates depth of focus
- provides neonverbal communication and social signaling
- attraction/mate selection
10
Q
Role of pupil in regulating light levels
A
Minimal role
11
Q
The pupils diameter of the human eye can vary between
A
2 and 8 mm
12
Q
How much does the pupil actually contribute to light regulation
A
1 mil: 16, not much at all
13
Q
Is the pupil more adapted for daylight changes or nighttime changes?
A
Daylight
14
Q
What could cause night time glare
A
LASIK, large pupils
15
Q
What happens to aberrations as pupil gets smaller
A
Decrease
16
Q
Smaller pupil and PSF
A
Better PSF
17
Q
What is the ideal pupil size
A
1-2mm
18
Q
Pupil below 1 mm
A
Diffraction limit
19
Q
Pupil larger than 2mm
A
Aberrations
20
Q
Smaller pupils increase ___________________ and can help compensate for loss of accommodation with age
A
The depth of focus
21
Q
Pupil size and age
A
Shrink
22
Q
Pupil size and trust
A
Subjects trust people with dilating pupils more than constricted pupils
23
Q
Pupil size and communication
A
Subjects pupils mimic those they communicate with
Dilation mimicry predicted trust among individuals
24
Q
Pupil size and sadness
A
Rated more sad with larger pupil
25
Pupil size and attractiveness
Rated more attractive with larger pupils in connection with happy expressions
26
Positive attributes and pupil size
Larger pupils=warmer attributes
27
Negative attributes and pupil size
Small pupils
28
Deception and eye signals
Increased blink rate, dilation, eye aversiooccassionaly used for lie detector testing
29
Pupil size and atttraction or interest
Increased dilation
30
What was used in the 4th century to make pupils larger to appear more attractive
Belladonna (deadly nightshade)
31
What does belladonna contain that dilates pupils
Atropine and scopolamine
32
Attraction/mate selection and iris
-attracted to similar color irides
33
Greater variability of eye color in which sex
Women
34
What do people usually pick for colored lenses
Colors that highlight their own color eyes
35
Average diameters of iris
12mm
36
How thick is iris at thinnest part of iris
500 microns
37
How is pupil centered
Slightly nasal and inferior to iris center
38
Abnormally decentered pupil
Ectopic, can degrade image quality
39
Where does pupillary margin rest
On anteiror surface of lens
40
How does aqueous humor flow
From posterior into anterior chamber through the pupil
41
4 layers of the iris
1. Anterior border layer
2. Stroma and sphincter muscle
3. Anterior epithelium and dilator muscle
4. Posterior epithelium
42
What layer of the iris is different in everyone
Anteiror border layers
43
Is the anterior border layer a separate layer from stroma
No
44
What is contained int he anteiror border layer
Fibroblasts and pigmented melanocytes
45
What are the valleys called in the anteiror border layer of the iris
Oval shaped crypts
46
Anteiror iris synechia
Iris is attached up near trabecular mesh work, caused by birht or inflammation. Can block aqueous
47
This layer of the iris contains pigmented and nonpigmented cells, collagen fibrils, and extensive ground substance
Stroma
48
How are the collagen fibrils arranged in the stroma
Radial
49
What muscle lies within the stroma of the iris
Sphincter muscle
50
What is the sphincter muscle made up of
- Smooth muscle cells joined by tight junctions
- 0.75mm-1mmwide
- anchored to stroma
51
What does the sphincter muscle do
Constricts for miosis
52
What is the sphincter muscle innervated by
Parasympathetic
53
What contracts when you hit it with a laser
Collagen
54
Are the constrictor pupillae and dilator pupillae muscle contracted?
No
55
Apical portion of anterior epithelium in the iris
Pigmented epithelium joined by tight junctions facing towards the back
56
Basal portion of the anterior epithelium of the iris
Smooth muscle processes which extend into stroma (facing up)
57
Where does the dilator muscle extend to
A point below the midpoint of the sphincter
58
What does the dilator muscle cause and what is it innervated by
Mydriasis
| Sympathtic
59
What layer of the iris is heavily pigmented in everyone
Posterior epithelium
60
Make up of posterior epithelium
Columnar cells joined by tight junctions
61
How many layers are there to the posterior epithelium of the iris
Single layer
62
What is he diameter of the iris
12mm
63
Where is the major circle of the iris located
Ciliary body
64
What kind of course does the major circle of iris take
Radial
65
Why does the major circle of iris appear to be thick walled
Collagen fibrils encircling vessels
66
Where is hte major circle of hte iris located
Peripherally
67
Where is the minor circle of the iris
At junction of ciliary and pupillary portions, close to pupil
68
The minor circle of the iris is inferior to the
Collarette
69
What layer is the minor circle of the iris located
Iris stroma
70
What forms the blood aqueous barrier
Minor circle of the iris
71
Is the minor circle of the iris fenestrated?
Fenestrated
72
Ciliary muscle and sphincter muscle are innervated by
Parasympathetic efferent fibers from 3rd nerve
73
Dilator muscle is innervated by
Sympathetic efferent fibers which take a much longer route
74
What are the layers of the iris
1. Anterior border layer
2. Stroma and sphincter muscle
3. Anterior epithelium and dilator muscle
4. Posterior epithelium
75
You fire a YAG laser shot at the iris and see pigment coming out of the pupil. What layer caused this?
Posterior epithelium
76
You fire a diode laser shot at the iris and see black charred on the surface. What layer was affected
Anterior border layer
77
You fire an argon laser shot at the iris and see contraction around the spot. What layer was affected?
Stroma and sphincter muscle. Collagen contracts
78
You fire an infrared diode laser at the iris and notice radial movement from the pupil to the limbus. What layer was this?
Anteiror epithelium and dilator muscle
79
How frequently does the pupil dilate and constrict
Approximately 2 times per second
80
What is the typical range of constriction and dilation that happens constantly?
0.5mm
81
Rhythmic oscillation of pupil
Hippus
82
Under what light conditions does the pupi; react more rapidly?
Increased illumination
83
Pupil size always has an implicit
+ or - 0.2mm
84
Indicate problem with innervation or damage to iris
Absence of hippus
85
Root tears away from the ciliary body at its thinnest/weakest part
Iridodialysis
86
What can happen due to iridodialysis
- blood vessels and nerves can be damaged
- blood may hemorrhage into anterior and posterior chambers
- maybe result in sector paralysis
87
Number of melanocytes in iris
Constant between eye colors
88
What does eye color depend on
Number and type of melanin granules within the melanocytes
89
Why does the iris appear blue
Light scatter caused by arrangement and density of the connective tissue components
90
Why do old people get grey eyes
Corneal clouding
91
The color of the iris is caused by
The number of melanin granules within the melanocytes
92
What is a drug that could change eye color
Prostaglandin analog=glaucoma drugs can change iris color such as latanoprost
93
Pigment shed from posterior iris surface, deposited on iris, lens, corneal endothelium, or in trabecular mesh work. Can cause transillumination defects
Pigmentary dispersion synonyme (PDS)
94
Detectable differnce between pupil diameters (less than 0.4mm considered normal)
Anisocoria
95
Laser trabeculoplasty in one eye does what to the other
Yoking, pressure drops in both
96
Iridology
No validity, waste of time
97
```
Which of these is not a primary function of the iris?
A. Regulate optical aberrations
B. Regulate glare
C. Regulate DoF
D. Produce aqueous humor
E. Nonverbal communication
F. Social Signaling
```
D. Production of aqueous humor
98
Refers to displacement of the pupil that is associated with lens bubluxation. Pupils are often oval or slit shaped and they often dilate poorly.
Corectopia
99
The vibration or agitated motion of the iris with eye movement. This may be caused by lens subluxation, the incomplete or partial dislocation of the lens; or by aphakia, the absence of the lens
Iridodonesis
100
Pathological condition of the eye characterized by more than one pupillary opening in the iris
Polycoria
101
What percent of the population has anisocoria?
20%
