Intraocular Scatter 1

Question 1

When the scattering particles size is about the same size as the wavelength of light

Answer 1

Tyndall scattering (colloidal particle scattering)

Question 2

What does tyndall scattering act like?

Answer 2

More like rayleigh

Question 3

When ____________ are about the size of a wavelength wave effects result in tyndall scattering

Answer 3

Transparent particles

Question 4

Tyndall scattering is _______ dependent scattering (almost)

Answer 4

Wavelength

Question 5

Scattering profile of tyndall scattering

Answer 5

Scattering in more directions, not just forwards and back

Question 6

There is no dramatic changes due to the _____ during tyndall scattering

Answer 6

Absorption. More like rayleigh

Question 7

Tyndall scattering in opal

Answer 7

Tyndall scattering at these in-homogeneities leads to a bluish color in reflected light

Question 8

What gives blue eyes there blue appearance?

Answer 8

Tyndall scattering in the iris stroma

Question 9

Why does some of the light scatter back out of the eye in blue eyed people

Answer 9

In the absence of melanin, the translucent stroma scatter some of the light back out of the eye

Question 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

Answer 10

Shorter

Question 11

The blue iris is an example of a _________ color, unlike a pigmented color

Answer 11

Structural

Question 12

Why do albinos have red eyes?

Answer 12

They do not produce melanin. Their eyes color is red because the blood vessels behind the eyes are visible

Question 13

The incoherent scattering depends on the ________ size

Answer 13

Particles

Question 14

Is there is a smaller wavelength, what kind of scattering?

Answer 14

Mie

Question 15

What causes scattering in mie scattering?

Answer 15

Reflection and refraction Caucasus scattering

Question 16

Direction of scattering mie scattering

Answer 16

Forward

Question 17

Mie scattering is _______ independent

Answer 17

Wavelength

Question 18

Example of mie scattering

Answer 18

Whiteness of the clouds

Question 19

What kind of scattering has particle size equal to the wavelength of light

Answer 19

Tyndall

Question 20

What causes the scattering in tyndalll

Answer 20

Interior wave effects causes scattering (diffraction)

Question 21

Direction of scattering in tyndall

Answer 21

Spread light out in more direction

Question 22

Tyndall scattering is ________ dependent

Answer 22

Wavelength

Question 23

Examples of tyndall scattering

Answer 23

Halos seen though a fogged up car window

Question 24

If the particle size is smaller than that of the wavelength, what type of scattering?

Answer 24

Rayleigh

Question 25

What causes scattering in rayleigh

Answer 25

Dipole re-radiation causes scattering

Question 26

What direction does rayleigh scattering have?

Answer 26

All directions

Question 27

What kind of wavelength dependence does rayleigh scattering have?

Answer 27

Stronger dependence at shorter wavelengths (blue) than on the longer wavelength

Question 28

Example of rayleigh scattering

Answer 28

Blue sky

Question 29

What kind of scattering is responsible for the sky looking whiter near the sun?

Answer 29

Mie

Question 30

What scattering scatters roughly equally in all directions

Answer 30

Rayleigh

Question 31

When reflected and transmitted light are perpendicular in rayleigh scattering gives strong _________

Answer 31

Polarization

Question 32

Orange sunset is what type of scattering?

Answer 32

Multiple

Question 33

Green flash at sunset

Answer 33

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.

Question 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

Answer 34

Coherent scattering

Question 35

In coherent scattering, particles are much _______ than the wavelength of the light

Answer 35

Smaller

Question 36

Each particle acts as a _____ for the coherent scattered waves

Answer 36

Source

Question 37

Scattered waves propagate _______ and overlap in coherent

Answer 37

Outward

Question 38

Coherent scattering acts as a

Answer 38

Diffraction grating

Question 39

Many coherent scattered waves interfere destructively in ______ directions

Answer 39

Most

Question 40

Many coherent scattered waves interfere constructively in _____ directions

Answer 40

Two

Question 41

Constructive coherent scattering in 2 directions

Answer 41

- Parallel to incident light (forward scatter) | - refract relative to incident wave (phase shifted)

Question 42

Light scatter leads to deleterious visual effects like

Answer 42

- glare while night driving - hindrance from low sun during daytime - facial recognition problems - haziness of vision - color and contrast loss

Question 43

Sources of ocular scatter

Answer 43

- cornea - sclera and iris - lens - vitreous humor - retina

Question 44

Forward scattering (FWS)

Answer 44

Light going into the eye

Question 45

Backward scattering (BWS)

Answer 45

Light reflecting back from the fundus

Question 46

Eye is assessed by ______ light scatter, using slit lamp mainly

Answer 46

Backward

Question 47

______ light scatter is studied in vitro in human donor lenses

Answer 47

Forward

Question 48

What is BWS used for

Answer 48

Dx

Question 49

What is FWS used for

Answer 49

Function of vision, human donor lenses

Question 50

What does the corneal endothelium do

Answer 50

Pumps excess water out of the cornea into the aqueous humor

Question 51

Reasoned for scattering in cornea

Answer 51

Loses its transparency and takes on grayish appearance, scar tissue on the cornea

Question 52

The collagen fibers in sclera have ______spacing than the wavelength of light, causing what kind of scattering

Answer 52

Larger | Mie scattering

Question 53

Due to ___________, sclera appears whitish

Answer 53

Large particle incoherent forward scattering

Question 54

Sclera thinning

Answer 54

Fibers get smaller and sclera takes on a bluish color due to rayleigh type scattering Functional effect

Question 55

Melanin and scleral function

Answer 55

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

Question 56

______ pigments in the lens scatter more light (forward scatter)

Answer 56

Yellow Functional effect

Question 57

Cataract and scattering

Answer 57

Fluid pools

Question 58

Floaters

Answer 58

Coalescing of collagen fibers causes fluid packets, developing a localized scattering, this causes floating specks and threads

Question 59

Retina scatters light as much as the ______

Answer 59

Cornea | 1/3 bws

Question 60

How does rental scattering increase

Answer 60

When blood circulation/supply is interrupted, the retinal integrity is damaged, and edema fluid starts collecting in the nerve fiber layer. This increases retinal light scattering turning the area into milky gray (cotton wool spots)