21: Spectral Transmission

Question 1

light may undergo specular reflection out of the eye, what is this observed as?

Answer 1

purkinje-sanson image

Question 2

list of things that may happen to light as it enters the eye

Answer 2

• specular reflection
• backward or forward scatter
• absorption
• non-scattered transmittance

Question 3

cumulative spectral transmittance plot shoes

Answer 3

the percentage of incident light that reaches the posterior corneal surface (C), the posterior aqueous (A), the posterior crystalline lens surface (L), and the posterior vitreous (V)

Question 4

UV-C and UV-B absorbed heavily by

Answer 4

cornea

Question 5

UV-A absorbed heavily by

Answer 5

cornea, aqueous, and lens

Question 6

visible and IR-A absorbed by

Answer 6

all components (cornea, aqueous, lens, vitreous)

Question 7

IR-B absorbed heavily by

Answer 7

cornea and aqueous

Question 8

cornea changes with high UV dose

Answer 8

the corneal epithelium cells are damaged and slough off

photokeratitis

Question 9

what can occur if a crystalline lens is removed or replaced with an intraocular lens

Answer 9

UV radiations may reach the retina because the vitreous transmits these wavelengths quite well

Question 10

what does the macular area contain

Answer 10

yellow pigment carotenoids

Question 11

what are the 2 of the many carotenoids that are concentrated at the fovea

Answer 11

lutein and zeaxanthin

Question 12

mean density of pigment at the foveola

Answer 12

(at 460nm) is about 0.6 log10 (transmittance of 25%)

Question 13

there is little pigment beyond ___

Answer 13

4 degrees eccentricity

Question 14

the macular pigment may be observed entropically as

Answer 14

maxwell’s spot

Question 15

the macular pigment is concentrated around the

Answer 15

Henle fibers

Question 16

what are Henle fibers

Answer 16

foveal cone axons within the outer plexiform layer that travel radially to the displaced cells of the inner nuclear layer

Question 17

macular pigment is also concentrated in what layer

Answer 17

in the inner plexiform layer

Question 18

what does the macular pigment do?

Answer 18

it filters the light before it can reach the photoreceptor layer

Question 19

the macular pigment has peak absorption at:

Answer 19

about 460nm

Question 20

macular pigment absorbs in the range of:

Answer 20

400-520nm

Question 21

what can macular pigment reduce the effects of?

Answer 21

of chromatic aberrations

Question 22

macular pigment changes to contrast sensitivity

Answer 22

it improves contrast sensitivity by reducing the effects of atmospheric scatter over large terrestrial distances

Question 23

how is macular pigment speculated to have a protective role at the macula?

Answer 23

by absorbing short wavelength light (blue light)