Eye 1

Question 1

What is a vision finding in multiple sclerosis?

Answer 1

A common finding is blurry vision secondary to optic neuritis. Multiple sclerosis is a demyelinating disease and can affect one of the two optic nerves

Question 2

What happens to vision when there is a pituitary adenoma present?

Answer 2

First, pituitary enlargment could be an impingement on the optic chiasm. There will be bilateral hemianopsia (loss of peripheral vision) because bilateral medial fibers are compromised.

Question 3

If there is a lesion of the oculomotor nerve, what happens?

Answer 3

The eye would be down and out at rest, and the eyelid would be drooping.

Question 4

If there is a lesion in the temporal lobe, the result is ____.

Answer 4

“Pie in the sky” - a bilateral upper quadrant visual field defect in the contralateral side.

Question 5

What happens if you lesion the optic tract?

Answer 5

You will have a contralateral visual field will be affected (homonymous hemianopsia).

Question 6

If there is a lesion of the abducens nerve, what happens?

Answer 6

The lateral rectus won’t function, so when the patient is instructed to look to the side with the lesion, the pupil will laterally rotate, but will not move beyond the midline.

Question 7

What is the function of rods?

Answer 7

These are low-acuity, low-light photoreceptors found peripherally on the retina. Rods provide night vision.

Question 8

If there is a lesion of the oculomotor nerve, what happens?

Answer 8

The eye would be down and out at rest, and the eyelid would be drooping.

Question 9

If there is a lesion of the trochlear nerve, what happens?

Answer 9

This nerve innervates the superior oblique; as such, the eyeball will be rotated medially and superiorly (up and in). Patients will also complain of diplopia and of problems with reading or going down the stairs (both of which require looking down).

Question 10

What happens if you have a lesion at the primary motor cortex (from a posterior cerebral artery stroke)?

Answer 10

Homonymous hemianopsia with macular sparing.

Question 11

What is the function of cones?

Answer 11

They detect color and are located centrally.

Question 12

The constriction of the pupil is mediated by _______ neurons acting on ___ acetylcholine receptors.

Answer 12

Parasympathetic, M3

Question 13

The epithelium of the cornea is derived from _____.

Answer 13

Skin ectoderm.

Question 14

What is accommodation?

Answer 14

The pupils constrict when vision shifts from distant to near.

Question 15

Dilator muscles are innervated by ______, and dilate the iris using ____ adrenergic receptors.

Answer 15

sympathetics, beta1

Question 16

What does constriction of the pupil mean?

Answer 16

It means the iris closes, covering more of the lens.

Question 17

What is retinal detachment?

Answer 17

It is the result of the retinal epithelium having been ripped off of the basement membrane.

Question 18

What is the function of the cornea?

Answer 18

It is structured to minimize the absorption and refraction (bending, focusing) of light (bending, focusing) and act as an outer limit for the anterior chamber’s aqueous fluid.

Question 19

What does dilation of the pupil mean?

Answer 19

Neuroscience
The Eye—Anterior Eye
What does dilation of the pupil mean?
See Answer
It means the iris retracts away from the center and towards the angle, covering less of the lens.

Question 20

Why are the irises of both eyes able to constrict at the same time?

Answer 20

It is because the optic nerve carries a signal from the retina to the pretectal nucleus in the midbrain. From there, axons of neurons in the pretectal nucleus go to both Edinger-Westphal nuclei. That is, the sensory fibers come in through the optic nerve bilaterally, and both pretectal nuclei have motor projections to bilateral Edinger-Westphal nuclei, and therefore both have an increase in parasympathetic discharge to their ciliar ganglion, ultimately resulting in more sphincter contraction.

See Question

Question 21

What is the role of the iris?

Answer 21

The iris controls exposure - how much light the retina gets.

Question 22

Why are the irises of both eyes able to constrict at the same time?

Answer 22

It is because the optic nerve carries a signal from the retina to the pretectal nucleus in the midbrain. From there, axons of neurons in the pretectal nucleus go to both Edinger-Westphal nuclei. That is, the sensory fibers come in through the optic nerve bilaterally, and both pretectal nuclei have motor projections to bilateral Edinger-Westphal nuclei, and therefore both have an increase in parasympathetic discharge to their ciliar ganglion, ultimately resulting in more sphincter contraction.