Visual Pathway (Thurtell)

Question 1

this type of vision has high acuity, has excellent color perception, and functions best in light-adapted conditions; it’s light receptors are cones

Answer 1

central (macular) vision

Question 2

this type of vision has low acuity, has poor color perception, works best in dark-adapted conditions; it’s light receptors are rods

Answer 2

peripheral (ambulatory) vision

Question 3

For the best visual perception, the image of the object of interest must fall on the _____, which is the most sensitive part of the macula and has the greatest density of cone photoreceptors

Answer 3

fovea

Question 4

this type of photoreceptor is greatest in density 20 degrees from the fovea and are more abundant than cones in the peripheral retina

Answer 4

rods

Question 5

why is there a blind spot in the visual field ~15 degrees from the fovea (center of the macula)?

Answer 5

this is the position of the optic nerve, where there are no light receptors

Question 6

True or false: axons that arise from the ganglion cells of the nasal retina of each eye cross in the optic chiasm to the contralateral optic tract, whereas axons from the temporal retina do not cross

Answer 6

True. The percentages of crossed and uncrossed axons in the optic chiasm are approximately 53% and
47%, respectively, with the nasal retina receiving visual information from the temporal visual field, and the temporal retina receiving visual information from the nasal visual field.

Question 7

visual information from the optic tract passes to this relay station of the thalamus

Answer 7

lateral geniculate nucleus

Question 8

day blindness; involves dysfunction in cone cells

Answer 8

hemeralopia

Question 9

night blindness; involves dyscuntion in rod cells

Answer 9

nyctalopia

Question 10

an inherited retinal disease that produces visual field constriction with striking pigmentary and atrophic changes in the periphery of the retina, with relative sparing of the macula

Answer 10

retinitis pigmentosum

Question 11

central vision loss, decreased color and contrast vision, relative afferent pupillary defect, and optic disc changes are all featured in what type of disease?

Answer 11

optic nerve disease

Question 12

an optic nerve disease characterized by a central visual defect connected to the blind spot

Answer 12

cecocentral scotoma

Question 13

during the swinging flashlight test, you notice an absence of the pupillary light reflex when you shine your light in the patient’s right eye, and proper pupillary constriction of both eyes when shining your light in the left. what kind of damage does this indicate?

Answer 13

damage to the right optic nerve

Question 14

name 3 common causes of optic nerve disorder

Answer 14

glaucoma, optic neuritis, ischemic optic neuropathy, tumor compression