Color Vision Abnormalities

Question 1

normal color vision

Answer 1

trichromatism, or trichromacy

Question 2

long- wavelength

Answer 2

red

Question 3

middle- wavelength

Answer 3

green

Question 4

short- wavelength

Answer 4

blue

Question 5

red

Answer 5

long- wavelength

Question 6

green

Answer 6

middle- wavelength

Question 7

long- wavelength

Answer 7

red

Question 8

Hereditary congenital color vision defects - genetics

Answer 8

X- linked- recessive

Question 9

Hereditary congenital color vision defects - color

Answer 9

red- green

Question 10

Hereditary congenital color vision defects - epidemiology

Answer 10

5%–8% of males and 0.5% of females

Question 11

Acquired defects - color

Answer 11

blue- yellow, or tritan

Question 12

Individuals who need only 2 primary colors

Answer 12

dichromacy. It is assumed that such individuals lack 1 of the cone photopigments

Question 13

An absence of color discrimination

Answer 13

achromatopsia

Question 14

forms of achromatopsia and signs

Answer 14

rod monochromatism, and (2) S- cone monochromatism (blue- cone monochromatism). Both disorders typically pres ent with congenital nystagmus, poor visual acuity, and photophobia

Question 15

differentiate achromatopsia from congenital motor nystagmus or ocular albinism

Answer 15

Electroretinography (ERG) testing helps differentiate achromatopsia from congenital motor nystagmus or ocular albinism, both of which are associated with normal cone ERGs

Question 16

Rod monochromatism - other name

Answer 16

complete achromatopsia

Question 17

complete achromatopsia - other name

Answer 17

Rod monochromatism

Question 18

most severe form

Answer 18

Rod monochromatism (complete achromatopsia) have normal rod function but no detectable cone function and see the world in shades of gray.

Question 19

Rod monochromatism - diagnostics

Answer 19

ERG pattern in patients with rod mono- chromatism shows an absence of cone- derived responses and normal rod responses. Dark adaptometry shows no cone plateau and no cone– rod break.

Question 20

Rod monochromatism - genetics

Answer 20

autosomal- recessive inheritance

Question 21

S- cone (or blue- cone) monochromatism - pathophysiology

Answer 21

function of rods and S cones is normal, but L- and M- cone function is absent

Question 22

S- cone (or blue- cone) monochromatism - genetics

Answer 22

X- linked

Question 23

S- cone (or blue- cone) monochromatism - diagnostics

Answer 23

preserved S- cone ERG responses, severely reduced cone flicker ERGs, and normal rod ERGs.

Question 24

Congenital stationary night blindness - genetics

Answer 24

most often x-linked

Question 25

Congenital stationary night blindness - features

Answer 25

normal to 20/200, nystagmus, may high myopia, may have paradoxical pupillary response

Question 26

Congenital stationary night blindness - diagnostics

Answer 26

Dark-adaptometry curves reveal markedly reduced responses, negative ERG in which the bright- flash, dark- adapted ERG has a normal (or near- normal) a- wave but a markedly reduced b- wave (melanoma- associated retinopathy similar)

Question 27

Fundus albipunctatus - signs

Answer 27

night blind from birth and usually exhibit yellow- white dots in the posterior pole extending into the midperiphery, but sparing the fovea. visual acuity and color vision are usually good

Question 28

Fundus albipunctatus - diagnostics

Answer 28

ERG responses commonly show a cone- isolated retina pattern, with undetectable rod- specific ERG, and a severely reduced bright- flash dark- adapted ERG (arising in dark- adapted cones) that normalizes with sufficiently extended dark adaptation.

Question 29

Fundus albipunctatus - differential

Answer 29

retinitis punctata albescens

Question 30

retinitis punctata albescens - features

Answer 30

progressive rod– cone dystrophy, the white dots may be finer than those of fundus albipunctatus, and there may be attenuation of the retinal vessels. ERG responses are usually very abnormal

Question 31

Mizuo-Nakamura phenomenon

Answer 31

Patients with Oguchi disease are also night blind from birth. The fundus in eyes with Oguchi disease is - normal after dark adaptation but shows a peculiar yellow iridescent sheen alteration after even brief exposure to light