Flashcards in Intraocular Scatter 1 Deck (60):
1
When the scattering particles size is about the same size as the wavelength of light
Tyndall scattering (colloidal particle scattering)
2
What does tyndall scattering act like?
More like rayleigh
3
When ____________ are about the size of a wavelength wave effects result in tyndall scattering
Transparent particles
4
Tyndall scattering is _______ dependent scattering (almost)
Wavelength
5
Scattering profile of tyndall scattering
Scattering in more directions, not just forwards and back
6
There is no dramatic changes due to the _____ during tyndall scattering
Absorption. More like rayleigh
7
Tyndall scattering in opal
Tyndall scattering at these in-homogeneities leads to a bluish color in reflected light
8
What gives blue eyes there blue appearance?
Tyndall scattering in the iris stroma
9
Why does some of the light scatter back out of the eye in blue eyed people
In the absence of melanin, the translucent stroma scatter some of the light back out of the eye
10
Tyndall scattering in a blue takes place to a greater extent at the _____ wavelengths and it viewed against the dark background of the iris pigmented epithelium
Shorter
11
The blue iris is an example of a _________ color, unlike a pigmented color
Structural
12
Why do albinos have red eyes?
They do not produce melanin. Their eyes color is red because the blood vessels behind the eyes are visible
13
The incoherent scattering depends on the ________ size
Particles
14
Is there is a smaller wavelength, what kind of scattering?
Mie
15
What causes scattering in mie scattering?
Reflection and refraction Caucasus scattering
16
Direction of scattering mie scattering
Forward
17
Mie scattering is _______ independent
Wavelength
18
Example of mie scattering
Whiteness of the clouds
19
What kind of scattering has particle size equal to the wavelength of light
Tyndall
20
What causes the scattering in tyndalll
Interior wave effects causes scattering (diffraction)
21
Direction of scattering in tyndall
Spread light out in more direction
22
Tyndall scattering is ________ dependent
Wavelength
23
Examples of tyndall scattering
Halos seen though a fogged up car window
24
If the particle size is smaller than that of the wavelength, what type of scattering?
Rayleigh
25
What causes scattering in rayleigh
Dipole re-radiation causes scattering
26
What direction does rayleigh scattering have?
All directions
27
What kind of wavelength dependence does rayleigh scattering have?
Stronger dependence at shorter wavelengths (blue) than on the longer wavelength
28
Example of rayleigh scattering
Blue sky
29
What kind of scattering is responsible for the sky looking whiter near the sun?
Mie
30
What scattering scatters roughly equally in all directions
Rayleigh
31
When reflected and transmitted light are perpendicular in rayleigh scattering gives strong _________
Polarization
32
Orange sunset is what type of scattering?
Multiple
33
Green flash at sunset
Red and yellow go above the observer, blue goes below and green goes right to the observer. Must be very clear atmosphere with no pollution.
34
When the particles are much closer together than the coherence length of the light, constructive and destructive interference occurs between the waves scattered from different particles
Coherent scattering
35
In coherent scattering, particles are much _______ than the wavelength of the light
Smaller
36
Each particle acts as a _____ for the coherent scattered waves
Source
37
Scattered waves propagate _______ and overlap in coherent
Outward
38
Coherent scattering acts as a
Diffraction grating
39
Many coherent scattered waves interfere destructively in ______ directions
Most
40
Many coherent scattered waves interfere constructively in _____ directions
Two
41
Constructive coherent scattering in 2 directions
-Parallel to incident light (forward scatter)
-refract relative to incident wave (phase shifted)
42
Light scatter leads to deleterious visual effects like
-glare while night driving
-hindrance from low sun during daytime
-facial recognition problems
-haziness of vision
-color and contrast loss
43
Sources of ocular scatter
-cornea
-sclera and iris
-lens
-vitreous humor
- retina
44
Forward scattering (FWS)
Light going into the eye
45
Backward scattering (BWS)
Light reflecting back from the fundus
46
Eye is assessed by ______ light scatter, using slit lamp mainly
Backward
47
______ light scatter is studied in vitro in human donor lenses
Forward
48
What is BWS used for
Dx
49
What is FWS used for
Function of vision, human donor lenses
50
What does the corneal endothelium do
Pumps excess water out of the cornea into the aqueous humor
51
Reasoned for scattering in cornea
Loses its transparency and takes on grayish appearance, scar tissue on the cornea
52
The collagen fibers in sclera have ______spacing than the wavelength of light, causing what kind of scattering
Larger
Mie scattering
53
Due to ___________, sclera appears whitish
Large particle incoherent forward scattering
54
Sclera thinning
Fibers get smaller and sclera takes on a bluish color due to rayleigh type scattering
Functional effect
55
Melanin and scleral function
Although the function of sclera is to block the light entering the eye, they are not totally opaque. Light can get through sclera depending on the level of pigmentation and density of the structures generating intraocular scattering
Those without melanin may experience more scattering
56
______ pigments in the lens scatter more light (forward scatter)
Yellow
Functional effect
57
Cataract and scattering
Fluid pools
58
Floaters
Coalescing of collagen fibers causes fluid packets, developing a localized scattering, this causes floating specks and threads
59
Retina scatters light as much as the ______
Cornea
1/3 bws
60