unit 2b

Question 1

cataract

Answer 1

an opacity in the lens that block light f/ reaching retina; often occurs in older age due to sunlight (UV) exposure

Question 2

retinal colorblindness

Answer 2

inability to correctly see colors due to mutations in PR (ex; medium-length cones muted to respond like long-length cones)

Question 3

Monochromacy

Answer 3

a form of congenital achromatopsia ( color blindness) arising f/ problems in retina

Question 4

Rod monochromacy

Answer 4

rod monochromats are ppl whose cone PRs are present in retina but completely non-functional.

Cones can’t absorb light → patient relies only on rod vision (sees in black/white w/ low visual acuity)

Question 5

Cone monochromacy

Answer 5

patient has 1 func. cone type.
Color vision is restricted to abt 100 colors (normal ~10million)

Blue-cone monochromacy is rare, but more common than L/M cone monochromacy.

Question 6

Dichromacy

Answer 6

color vision disorder I which one type of cone is absent or nonfunc.

Question 7

Protanopia (dichromacy)

Answer 7

(L) PR deficit causes Red-Green colorblindness

Question 8

Deuteranopia (Dichromacy)

Answer 8

(M) PR deficit causes Red-Green colorblindness

Question 9

Tritanopia (S)

Answer 9

PR deficit causes Blue-Yellow colorblindness

Question 10

Red-Green colorblindness

Answer 10

a form of retinal colorblindness where either Green cones are missing or respond like Red cones.

More common in males

Question 11

Blue-Yellow colorblindess

Answer 11

A form of retinal colorblindness where people confuse Blue w/ green and Yellow w/ violet.

Very rare (1/10,000)- not sex-linked

Question 12

Anomalous trichromacy

Answer 12

Patients w/ types of anoumouls trichromacy (protanomaly, deuteranomaly, or tritanormaly) are trichromats, BUT color matches they make differ f/ normal

Question 13

Protanomaly (anomoulos trichromacy)

Answer 13

L-cone (RED) spectrum shifted closer to M-cone (GREEN) spectrum

Question 14

Deuteranomaly (Anom. Trichromacy)

Answer 14

M-cone (GREEN) spectrum shifted closer to L-cone (RED) spectrum

Question 15

Tritanomaly (Anom. trichromacy)

Answer 15

Blue-yellow discrimination altered

Question 16

Ishihara Plates

Answer 16

38 colored plates used to test those w/ red-green color blindness

Question 17

Tetrachromats

Answer 17

women who have 4 types of cones which allows them to see abt 100 million colors (normal: 10 mill)

4th type of cone occurs when women inherits 2 diff L-cone alleles (gene subtype)- each of which codes for an l-cone photopigment w/ small mutation that makes it absorb a slightly diff wavelength of light.

Due to process: X-chromosome Inactivation (in every female cell, 1 of the X-chromosomes os randomly inactivated), each retinal L-cone cell may randomly express 1 L-cone allele or the other.

Opponency syst. can incorp. the 2 slightly diff L-cones as indiv. PR types. Brains can instead make a more complex opponent system that allows tetrachromats to see more colors.

Question 18

Scotoma

Answer 18

An area of impaired/lost vision in the visual field.

Can arise f/ damage along the visual pathway f/ the retina to primary visual cortex (V1)

Beyond V1, more specialized types of visual disorders arise (ex: visual object agnosia)

Diff. extents of a scotoma that can occur due to very specific locations of damage:
Unilateral field loss, Hemianopsia, Bitemporal hemianopsia, Binasal hemianopsia, Homonymous hemianopsia

Question 19

Homonymous hemianopsia

Answer 19

blindness in same hemisphere of visual field in both eyes due to damage in OPPOSITE HEMISPHERE OF CORTEX (often f/ stroke/trauma)

‘Right homonymous hemianopsia’ refers to loss of right hemifield of vision in each eye f/ damage to left V1

Question 20

Binasal hemianopsia

Answer 20

Blindness in middle halves of visual field in BOTH eyes

Due to damage to UNCROSSED FIBERS (often due to calcification of carotid arteries; also assoc w/ hydrocephalus

Question 21

Bitemporal hemianopsia

Answer 21

Blindness in outer halves of visual field in BOTH eyes.

Due to damage to OPTIC CHIASM (tumors often culprit)

Question 22

Hemianopsia

Answer 22

Blindness in one half of the visual field in 1 or BOTH eyes.

Question 23

Unilateral field loss

Answer 23

Loss of an ENTIRE eye’s vision due to tumor/trauma that results f/ DISCONNECTION OF OPTIC NERVE.