Chapter 6

Question 1

How are anomalies of color vision classified?

Answer 1

Pigment affected
Nature of the defect

Question 2

What are the red-green defects for dichromacy?

Answer 2

Proton defect- protanopia

Deutan defect- deuteranopia

Question 3

What is the blue-yellow defect for dichromacy?

Answer 3

Tritanopia

Question 4

What is the red-green defect for anomalous trichromacy?

Answer 4

Protan defect- protanomalous trichromacy (protanomaly)

Deutan defect- deuteranomalous trichromacy (deuteranomaly)

Question 5

What is the blue-yellow defect for anomalous trichromacy?

Answer 5

Tritanomalous trichromacy (tritanomaly)

Question 6

Define dichromacy.

Answer 6

Missing one of the 3 cone pigments

Question 7

Define anomalous trichromacy.

Answer 7

Absorption spectrum of one photopigment is abnormal (less effect) (displaced from normal location)

Less effect

Question 8

Define deuteranomoly.

Answer 8

Chlorolabe spectrum displaced to long wavelengths

Question 9

Define protoanomaly.

Answer 9

Erythrolabe displaced to shorter wavelengths

Question 10

What is the peak luminous efficiency related to brightness?

Answer 10

555nm

Question 11

Describe luminosity in protan and Deutan defects.

Answer 11

Luminosity is abnormal in protan defects (L cone defect), but close-to- normal in deutan defects

Question 12

Describe wavelength discrimination in dichromacy. When do dichromate’s behave as monochromats?

Answer 12

Good discrimination at shorter wavelengths but beyond 545nm there is no ability to discriminate between stimuli on the basis of wavelength alone

Monochromatic beyond 550nm

Question 13

Describe the perception of saturation in people with anomalous in color vision.

Answer 13

Saturation is abnormal
Deuteranopia and Protanopia reach total white

Question 14

Describe how the spectrum of color looks to patients with anomalous color vision.

Answer 14

Protanopia- blue to white to yellow, longer wavelengths are darker, missing erythrocyte

Deuteranopia- blue to white to yellow

Protanopia and Deuteranopia appear as monochromats beyond 550nm

Tritanopia green to white to red

Question 15

Which red-green anomalies are autosomal dominant?

Answer 15

Tritanopia and tritanomaly (common inheritance)

Question 16

What is the most prevalent color vision anomaly?

Answer 16

Deuteranomaly

Question 17

How did hereditary red-green color vision anomalies originate?

Answer 17

During meiosis dichromacy can originate when crossover of M and L is incorrect resulting in one chromosome with no M pigment (offspring who inherit this will have deuteranopia)
Paired copy will have 2 copies of M pigment and 1 L offspring will have normal color vision

Intragenic- hybrid genes result, can have dichromacy, anomalous trichromacy or normal

Question 18

What does the farnsworth D-15 arrangement test?

Answer 18

Protan, Deutan Tritan defects

Dose not distinguish dichromacy from anomalous trichromacy

Question 19

How does the radius of the desaturated D-15 compare to the saturated?

Answer 19

desaturated has shorter radius

Question 20

Describe the rabin cone contrast test.

Answer 20

Test function of 3 cone types
Determine stability useful for glaucoma

Question 21

Describe the Nagel anomaloscope.

Answer 21

Allows the full diagnosis of inherited red-green anomalies
Can diagnose dichromacy and anomalous trichromacy

Question 22

Does the X-chrom lens cure colorblindness?

Answer 22

Make monochromat a dichromat with red lens