Intraocular Light Scatter II Flashcards Preview

Optics BLOCK 4 > Intraocular Light Scatter II > Flashcards

Flashcards in Intraocular Light Scatter II Deck (46):
1

What are the two refractive surfaces of the eye?

Cornea and lens

2

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

3

What parts of the eye cause forward scattering?

Cornea, sclera and iris, lens, vitreous humor

4

What parts of the eye cause backward scattering?

Retina
This gives us access to understand the function of the eye

5

What does scleral thinning cause?

Bluish appearance due to rayleigh scattering

6

Corneal light scattering is _______ for all healthy eyes, and for all ages

Identical (constant)

7

Corneal transmittance is _________ dependent

Wavelength
(Rayleigh scattering)

8

When the wavelength increases, the corneal transmittance _________

Increases

9

Contact lens wearers experience a _______________

Significantly higher light scatter

10

On average, contact lens scatter is ___________ higher than spectacle wearers

0.22 log units

11

Corneal light scatter may increase __________

Post laser refractive surgery

12

Light scatter in the cornea

-constant in all healthy eyes
-wavelength dependent
-increases with contacts and corrective surgery

13

For radial keratotomy (RK) mean stray light increases by a factor of ______ in eyes with 4mm pupil and a factor of _________for 8mm pupil.

1.4
2 (0.3 log units)

14

Photorefractice keratotomy (PRK) does what for light scattering in the cornea?

Corneal backscattering of light, which correlates with visible haze, is significantly stronger after PRK

15

Laser assisted in situ keratomileusis (LASIK) does what for corneal light scatter?

Epithelial ingrowth after LASIK can cause an increase in straylight

16

Corneal refractive therapy (CRT) and corneal light scatter

Reported decreased scatter in the follow ups

17

Which refractive procedure reduces decreased scatter in the cornea?

CRT

18

What does a pigmented iris do to scattering?

Decreases it

19

As angle of scatter increases, scatter ________ in blue eyes a lot

Increases

20

Are the scare and iris opaque?

Not totally, some pigment is here as well as in the iris

21

What do the sclera and iris due since they do have pigment

Diffusely transmit long wavelengths due to the color of pigments in the scleral wall and iris

22

For a dark brown eye of pigmented individuals, transmission is lower by _________

Two orders of magnitude

23

The amount of scatterin/stray light in the eye depends also on ________

Pigmentation of the fundus

24

Fundus has a stronger reflectance of __________ wavelengths due to the pigments and the blood

Longer (red)

25

Blue eyes cause greater what?

Back scattering of light from fundus and more light transmission through the eye wall

26

What pupil size has the highest scatter?

2-3 mm

27

What happens to scatter in pupils with 4-10mm pupils?

Scatter remains the same

28

Light scattering by the crystalline lens and age

Increases significantly with age and much higher for cataracts
-increases by 2x by age of 65
-increases by 3x by age 77

29

Results of water absorption and subsequent phase separation within the IOL matrix and are clinically observed in almost all types of IOL material, including hydrophobic and hydrophilic acrylics, silicone, and PMMA

Glistening

30

What kind of lens has less scatter than a normal healthy eye

Monofocal

31

What does glistening cause

Stronger glare, especially when driving

32

What does scatter reduce?

-contrast and VA

33

Introduced IOLS to reduce the amount of blue light transmission in the eye

Blue light blocker

34

Light scatter is stronger with _____

Blue

35

Benefits of blue light blocker

-drastically reduces light scatter
-blocks blue iChat harmful to retina
-reduce aberrations of the eye
-do not affect VA, CS, and color vision

36

What are some potential side effects of reduction in blue light?

Color vision disturbance
Decreased scoptopic sensitivity
-sleep-wake timing disruption

37

Effects of light scattering: cornea

-constant
-forward scattering

38

Effects of light scattering: sclera and iris

-pigmentation
-diffuse transmission of red

39

Effects of light scattering: lens

-forward light scattering
-age and cataract dependent

40

Effect of light scattering: vitreous

-forward scattering
-age

41

Effect of light scattering: retina

-backward scattering
-pigmentation
-fundus reflectance

42

Radiation of sharp needles of light that is perceived subjectively around a bright point light source that originates from light scattering by small particles

Ciliary corona

43

Color banded, much like the rainbow, perceived surrounding a bright spot of light at a mean distance of 3 degree radius.

Lenticular halo

44

Originates from the fibrous structure of the eye lens

Lenticular halo

45

The lens fibers form a diffraction grating, arranged in a circular fashion, much like the spokes of a wagon wheel

Lenticular halo

46

Appears only for larger pupil sizes, depending on the subject

Lenticular halo