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II. Neurophysiology and Perception > Rods, Purkinje, Monochromacy, Color Vision, and Nagel Anomaloscope (M1) > Flashcards

Rods, Purkinje, Monochromacy, Color Vision, and Nagel Anomaloscope (M1) Flashcards

1
Q

What is the fraction of incident photons that affect the eye?

A

Luminous efficiency

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2
Q

What are dark adapted or twilight conditions called?

A

scotopic

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3
Q

What measures the scotopic luminous efficiency function? 1. What are the methods to do this? 2

A
  1. photometry

2. absolute threshold in the dark or flicker photometry

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4
Q

What is the procedure for the absolute threshold measurement of the luminous efficiency of the eye in the dark?

A
  1. single flashes of light presented repeatedly
  2. each light has different wavelength
  3. intensity of each monochromatic light adjusted to just barely visible
  4. result is set of lights that are equated in visual effectiveness
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5
Q

What is the measurement of sensitivity relative to the threshold?

A

1/threshold = sensitivity

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6
Q

What controls the spectral sensitivity of the eye in the dark?

A
  1. spectral sensitivity of the rods (absorption spectrum of rhodopsin)
  2. transmission spectrum of the eye
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7
Q

What accounts for the loss in sensitivity in the scotopic spectral sensitivity as opposed to the rhodopsin absorption spectrum?

A

light being absorbed by the lens (variable per person)

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8
Q

What causes the increase in optical density with age?

A

exposure to UV-B radiation from sunlight

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9
Q

What controls photopic conditions?

A

cones

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10
Q

How is the photopic luminous efficiency function usually measured?

A

flicker photometry

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11
Q

What is the procedure of flicker photometry to measure the spectral sensitivity of the eye?

A
  1. pairs of lights (one usually white and the other monochromatic) alternate quickly
  2. intensity of the monochromatic light adjusted to minimize the flicker
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12
Q

Which is more sensitive at the max luminous efficiency: scotopic or photopic conditions?

A

scotopic

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13
Q

Which is more sensitive at long wavelengths luminous efficiency: scotopic or photopic conditions?

A

photopic slightly

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14
Q

Which cone has a minor contribution to the photopic luminous efficiency function?

A

S-cone

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15
Q

What is due to the relative spectral sensitivities of the photopic and scotopic luminous efficiency functions, and involves violets looking bright under scotopic conditions and roses looking brighter under photopic conditions?

A

Purkinje shift

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16
Q

What is the ability to make distinctions between visual stimuli, based only on the (wavelength) spectra they contain?

A

color vision

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17
Q

What does the spectral absorption function of each visual pigment relate to?

A

probability of absorption to the wavelength of light

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18
Q

What is a visual pigments probability of absorption of a certain wavelength of light called?

A

spectral absorption function

19
Q

How do visual responses of a rod system to a stimulus vary from stimulus to stimulus?

A

vary in strength due to how many photons were absorbed (not wavelength)

20
Q

What is a person that has only one photoreceptor type and one visual pigment called?

A

achromat or monochromat

21
Q

If a patient requires only one knob to establish a match at any wavelength, what are they considered?

A

an achromat or monochromat

22
Q

What does having more than one cone type provide to the patient that a patient that has only one cone type does not have?

A

ability to discriminate between two different wavelengths

23
Q

What is a patient that can adjust every group of three primary lights to match the test light called? 1. How many knobs do they need to make a match on an anomaloscope? 2

A
  1. trichromat

2. 3

24
Q

What is a patient that can adjust every pair of two primary lights to match a test light called? 1. How many knobs do they need to make a match on an anomaloscope? 2

A
  1. dichromat

2, 2

25
Q

What is the region called after about 550 nm wavelength? 1. What is special about this region and why is it like this? 2.

A
  1. Rayleigh region

2. dichromatic region because S cones are extremely insensitive there

26
Q

What are the uses for the Nagel anomaloscope?

A
  1. diagnose red-green color vision deficiency
  2. diagnose rod monochromacy
  3. demonstrate color matching
27
Q

What is a patient with S-cones and M-cones but no L-cones called?

A

protanope

28
Q

What is a patient with S-cones and L-cones but no M-cones called?

A

deuteranope

29
Q

What is a patient with M-cones and L-cones but no S-cones called?

A

tritanope

30
Q

When testing in the Rayleigh region using a Nagel anomaloscope what does a protanope act like?

A

monochromat

31
Q

When testing in the Rayleigh region using a Nagel anomaloscope what does a tritanope act like?

A

dichromat

32
Q

When testing in the Rayleigh region using a Nagel anomaloscope what does a deuteranope act like?

A

monochromat

33
Q

What differs in the process of color matching between deuteranopes matching and protanopes matching?

A

deuteranopes match all colors a with a constant yellow (only need to alter wavelength to match) while protanopes need more yellow to match the green and less yellow to match the red

34
Q

What differs in the process of color matching between protanopes matching and rod monochromats matching?

A

rod monochromats require a huge amount of yellow to match the green (can’t get enough for pure green) or yellow and less yellow to match the red

35
Q

What is a person that has one pigment that is different from the normal L and M pigments called with one normal pigment?

A

anomalous trichromats

36
Q

Do deuteranopes, protanope, or rod monochromats refuse the normal match?

A

rod monochromats and anomalous trichromats

37
Q

What is the altered pigment sensitivity line for a deuteranomalous trichromat patient?

A

M-cone line

38
Q

What is the altered pigment sensitivity line for a protanomalous trichromat patient?

A

L-cone line

39
Q

If your patient accepts the match that you have made, what can rule them out as having?

A

anomalous trichromacy

40
Q

If the patient accepts that match that you have made, you set the machine to the extreme red and then extreme green, and they can cannot match on adjustments by them then what are they not?

A

protanope or deuteranope

41
Q

If the patient accepts that match that you have made, you set the machine to the extreme red and then extreme green, and they can can match on adjustments on both ends with the same luminance setting, what are they?

A

deuteranope

42
Q

If the patient accepts that match that you have made, you set the machine to the extreme red and then extreme green, and they can can match on adjustments on both ends with varying luminance settings, what are they?

A

protanope

43
Q

If the patient refuses your original match and makes adjustments that result in the red/green half being light green, what are they?

A

deuteranomalous trichromat

44
Q

If the patient refuses your original match and makes adjustments that result in the red/green half being orange, what are they?

A

protanomalous trichromat

II. Neurophysiology and Perception (24 decks)

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