Intraocular Light Scatter II

Question 1

What are the two refractive surfaces of the eye?

Answer 1

Cornea and lens

Question 2

Light scatter leads to deleterious visual effects like

Answer 2

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

Question 3

What parts of the eye cause forward scattering?

Answer 3

Cornea, sclera and iris, lens, vitreous humor

Question 4

What parts of the eye cause backward scattering?

Answer 4

Retina

This gives us access to understand the function of the eye

Question 5

What does scleral thinning cause?

Answer 5

Bluish appearance due to rayleigh scattering

Question 6

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

Answer 6

Identical (constant)

Question 7

Corneal transmittance is _________ dependent

Answer 7

Wavelength

Rayleigh scattering

Question 8

When the wavelength increases, the corneal transmittance _________

Answer 8

Increases

Question 9

Contact lens wearers experience a _______________

Answer 9

Significantly higher light scatter

Question 10

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

Answer 10

0.22 log units

Question 11

Corneal light scatter may increase __________

Answer 11

Post laser refractive surgery

Question 12

Light scatter in the cornea

Answer 12

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

Question 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.

Answer 13

1.4

2 (0.3 log units)

Question 14

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

Answer 14

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

Question 15

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

Answer 15

Epithelial ingrowth after LASIK can cause an increase in straylight

Question 16

Corneal refractive therapy (CRT) and corneal light scatter

Answer 16

Reported decreased scatter in the follow ups

Question 17

Which refractive procedure reduces decreased scatter in the cornea?

Answer 17

CRT

Question 18

What does a pigmented iris do to scattering?

Answer 18

Decreases it

Question 19

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

Answer 19

Increases

Question 20

Are the scare and iris opaque?

Answer 20

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

Question 21

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

Answer 21

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

Question 22

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

Answer 22

Two orders of magnitude

Question 23

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

Answer 23

Pigmentation of the fundus

Question 24

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

Answer 24

Longer (red)

Question 25

Blue eyes cause greater what?

Answer 25

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

Question 26

What pupil size has the highest scatter?

Answer 26

2-3 mm

Question 27

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

Answer 27

Scatter remains the same

Question 28

Light scattering by the crystalline lens and age

Answer 28

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

Question 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

Answer 29

Glistening

Question 30

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

Answer 30

Monofocal

Question 31

What does glistening cause

Answer 31

Stronger glare, especially when driving

Question 32

What does scatter reduce?

Answer 32

-contrast and VA

Question 33

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

Answer 33

Blue light blocker

Question 34

Light scatter is stronger with _____

Answer 34

Blue

Question 35

Benefits of blue light blocker

Answer 35

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

Question 36

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

Answer 36

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

Question 37

Effects of light scattering: cornea

Answer 37

- constant | - forward scattering

Question 38

Effects of light scattering: sclera and iris

Answer 38

- pigmentation | - diffuse transmission of red

Question 39

Effects of light scattering: lens

Answer 39

- forward light scattering | - age and cataract dependent

Question 40

Effect of light scattering: vitreous

Answer 40

- forward scattering | - age

Question 41

Effect of light scattering: retina

Answer 41

- backward scattering - pigmentation - fundus reflectance

Question 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

Answer 42

Ciliary corona

Question 43

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

Answer 43

Lenticular halo

Question 44

Originates from the fibrous structure of the eye lens

Answer 44

Lenticular halo

Question 45

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

Answer 45

Lenticular halo

Question 46

Appears only for larger pupil sizes, depending on the subject

Answer 46

Lenticular halo