Ch 9 Flashcards
A visual exam in an 80-year-old man shows he has a reduced ability to see objects in the upper and lower quadrants of the left visual fields of both eyes but some vision remains in the central regions of the visual field. The diagnosis is
A. central scotoma.
B. heteronymous hemianopia with macular sparing.
C. lesion of the optic chiasm.
D. homonymous hemianopia with macular sparing.
E. retinopathy.
D. homonymous hemianopia with macular sparing.
A 45-year-old woman who had never needed to wear glasses experienced diffculty reading a menu in a dimly-lit restaurant. She then recalled that as of late she needed to have the newspaper closer to her eyes in order to read it. A friend recommended she purchase reading glasses. Visual accommodation involves
A. increased tension on the lens ligaments.
B. a decrease in the curvature of the lens.
C. relaxation of the sphincter muscle of the iris.
D. contraction of the ciliary muscle.
E. increased intraocular pressure.
D. contraction of the ciliary muscle.
A 28-year-old man with severe myopia made an appointment to see his ophthalmologist when he began to notice flashing lights and floaters in his visual field. He was diagnosed with a retinal detachment. The retina
A. is epithelial tissue that contains photoreceptors.
B. lines the anterior one-third of the choroid.
C. has an inner nuclear layer that contains bipolar cells,
horizontal cells, and amacrine cells.
D. contains ganglion cells whose axons form the oculomotor
nerve.
E. contains an optic disk where visual acuity is greatest.
C. has an inner nuclear layer that contains bipolar cells,
horizontal cells, and amacrine cells.
A 62-year-old white woman experienced a rapid onset of blurry vision along with loss of central vision. A comprehensive eye exam showed that she had wet age-related macular degeneration. The fovea of the eye
A. has the lowest light threshold.
B. is the region of highest visual acuity.
C. contains only red and green cones.
D. contains only rods.
E. is situated over the head of the optic nerve.
B. is the region of highest visual acuity.
Which of the following parts of the eye has the greatest concentration of rods? A. Ciliary body B. Iris C. Optic disk D. Fovea E. Parafoveal region
E. Parafoveal region
Which of the following is NOT correctly paired?
A. Rhodopsin: retinal and opsin
B. Obstruction of the canal of Schlemm: elevated intraocular pressure
C. Myopia: convex lenses
D. Astigmatism: nonuniform curvature of the cornea
E. Inner segments of rods and cones: synthesis of the
photosensitive compounds
C. Myopia: convex lenses
The correct sequence of events involved in phototransduction in rods and cones in response to light is:
A. activation of transducin, decreased release of glutamate, structural changes in rhodopsin, closure of Na+ channels, and decrease in intracellular cGMP.
B. decreased release of glutamate, activation of transducin, closure of Na+ channels, decrease in intracellular cGMP, and structural changes in rhodopsin.
C. structural changes in rhodopsin, decrease in intracellular cGMP, decreased release of glutamate, closure of Na+ channels, and activation of transducin.
D. structural changes in rhodopsin, activation of transducin, decrease in intracellular cGMP, closure of Na+ channels, and decreased release of glutamate.
E. activation of transducin, structural changes in rhodopsin, closure of Na+ channels, decrease in intracellular cGMP, and decreased release of glutamate.
D. structural changes in rhodopsin, activation of transducin, decrease in intracellular cGMP, closure of Na+ channels, and decreased release of glutamate.
A 25-year-old medical student spent a summer volunteering
in the sub-Saharan region of Africa. ere he noted a high incidence of people reporting di culty with night vision due to a lack of vitamin A in their diet. Vitamin A is a precursor for the synthesis of
A. rods and cones.
B. retinal.
C. rod transducin.
D. opsin.
E. cone transducin.
B. retinal.
An 11-year-old boy was having di culty reading the graphs that his teacher was showing at the front of classroom. His teacher recommended he be seen by an ophthalmologist. Not only was he asked to look at a Snellen letter chart for visual acuity but he was also asked to identify numbers in an Ishihara chart. He responded that he merely saw a bunch of dots. Abnormal color vision is 20 times more common
in males than females because most cases are caused by an abnormal
A. dominant gene on the Y chromosome.
B. recessive gene on the Y chromosome.
C. dominant gene on the X chromosome.
D. recessive gene on the X chromosome.
E. recessive gene on chromosome 22.
D. recessive gene on the X chromosome.
Which of the following is not involved in color vision?
A. Activation of a pathway that signals di erences between S
cone responses and the sum of L and M cone responses
B. Geniculate layers 3–6
C. P pathway
D. Area V3A of visual cortex
E. Area V8 of visual cortex
D. Area V3A of visual cortex
A tumor was diagnosed near the base of the skull in a 56-year-old woman, impinging on her optic tract. Which of the following statements about the central visual pathway is correct?
A. Thefibers from each temporal hemiretina decussate in the
optic chiasm, so that the bers in the optic tracts are those from the temporal half of one retina and the nasal half of the other.
B. In the geniculate body, the bers from the nasal half of one retina and the temporal half of the other synapse on the cells whose axons form the geniculocalcarine tract.
C. Layers 2 and 3 of the visual cortex contain clusters of cells called globs that contain a high concentration of cytochrome oxidase.
D. Complex cells have a preferred orientation of a linear stimulus and, compared to simple cells, are more dependent on the location of the stimulus within the visual eld.
E. e visual cortex is arranged in horizontal columns that are concerned with orientation.
B. In the geniculate body, the bers from the nasal half of one retina and the temporal half of the other synapse on the cells whose axons form the geniculocalcarine tract.
