Lec 10

Question 1

Moving the point source in front of stationary eye (optimum conditions) → can determine depth (anterior- posterior) of media opacities

Answer 1

relative entoptic parallax

Question 2

entoptic field is aka

Answer 2

visual field

Question 3

Anterior opacities move with the source: source down

Answer 3

shadow moves down relative to center of Entoptic field

Question 4

Posterior opacities move against what?

Answer 4

the source relative to center of Entoptic field

Question 5

The more anterior or posterior an opacity, how is it relative to movement?

Answer 5

the more rapid the with or against movement

Question 6

Human macula contains ananalyzer that (under specific viewing conditions) can entoptically differentiate the transmission and extinction axes of plane polarized (P-state) light

Answer 6

transmits differently

Question 7

Macular analyzer has what type of properties?

Answer 7

polarizing (birefriengence) and dichroic (selectively absorbing blue light)

Question 8

Xanthophylls
tend to associate with Muller cell
fibers

Answer 8

“yellow” radial

analyzer

Question 9

Xanthophyll pigment aligned with radial Muller fiber arrangement in macular region →

Answer 9

→ analyzer radial

Question 10

Polarized white light affected differently depending on 90state of polarization:

Answer 10

! in transmission axis → free transmission ∴ effectively overcomes yellow filter
→ appears blue
! light perpendicular to transmission axis → fully absorbed by
xanthophyll pigment
→ white - blue = yellow

Question 11

90 degrees (transmission axis) appears what color?

Answer 11

blue

Question 12

180 degrees appears what color?

Answer 12

yellow

Question 13

135 degrees appears as what?

Answer 13

yellow axis is at 45 degrees

Question 14

if polarized light is 90 degrees, where is the blue color?

Answer 14

90 degrees

Question 15

Diagnosis of macular edema

Answer 15

even small amount of macular edema disrupts Muller cell fiber radial analyzer
→ Haidinger’s brushes not seen

Question 16

Detection of eccentric fixation (strabismus patient)

Answer 16

when fixating eccentrically, do not see Haidinger’s Brushes in Center

Question 17

Training central fixation

Answer 17

seeing Haidinger’s Brushes→tells patient when they are centrally fixating (feedback)

Question 18

maxwell’s spot

Answer 18

Histologic section through the macula revealing the yellow pigment, xanthophyll.
Yellow pigment preferentially absorbs short-wavelength light (blue) and leads to Maxwell’s spot, an entoptic phenomena

Question 19

Yellow pigment resides above the photoreceptors and extends across what?

Answer 19

a ~2 mm (6.7 deg) diameter area that is centered on the fovea.

Question 20

The middle- and long- wavelength sensitive cones are selectively adapted to the yellow so that their response is attenuated while subsequently looking through the blue, thereby enhancing what?

Answer 20

visual effect of the macula.

Question 21

Purple light on a patient’s retina, patient will see a ____ spot.

Answer 21

red (long wave lengths)