W1: Visual Aspects

Question 1

Which 3 factors affect PSF

Answer 1

Diffraction, Scattering, Abberations

Question 2

Define Rayleigh Criterion

Answer 2

For 2 objects to be resolvable they must be separated by at least the airy disc radius

Question 3

Describe the nature of light and what determines its colour

Answer 3

Light exists as a wave and colour is determined by its illumination and reflected wavelengths

Question 4

Define chromatic aberration and how they’re reduced in the eye

Answer 4

Light of varying wavelengths spread due to diffraction; reduced by a yellow pigment in the fovea absorbing maximally at 460nm

Question 5

How does PSF affect resolution?

Answer 5

Smaller PSF means more resolved
Larger PSF means less/not resolved

Question 6

Explain adaptive optics and it’s purposes

Answer 6

Corrects monochromatic aberrations via deformable mirror deflecting rays to be parallel post-reflection
Images individual cells to detect early eye disease
Correlates retinal structure/function

Question 7

How is sun radiation reduced?

Answer 7

Absorbed by atmospheric scattering

Question 8

Describe monochromatic aberrations in a patient

Answer 8

Constantly fluctuating and noticeable in kerataconus

Question 9

How is scattering of light reduced at the central fovea

Answer 9

Peeling back of photoreceptors

Question 10

Name 2 artificial light sources

Answer 10

Fluorescent
Tungsten