Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Opthalmology > Eye Physiology > Flashcards

Eye Physiology Flashcards

1
Q

What is the function of the eye?

A

The function of the eye is to transform light energy into nerve signals that can be transmitted to the cerebral cortex for interpretation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pupillary Reflex is controlled by?

A

Automonic nervous sytems

Cranial nerve II AND III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Miosis

A

Stimulation of the parasympathetic nerves EXCITES the pupillary sphincter muscle, thereby decreasing the pupillary aperture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Mydriasis

A

Sympathetic stimulation, conversely, dilates the pupil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pulliary light reflex

A

Light shine constricts pupils

Functions to allow adaptation with rapid changes of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Direct response (pupil illuminated)

A

The direct response is impaired in lesions of the ipsilateral optic nerve, the pretectal area, the ipsilateral parasympathetics traveling in CN III, or the pupillary constrictor muscle of the iris.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Consensual response (contralateral pupil illuminated

A

The consensual response is impaired in lesions of the contralateral optic nerve, the pretectal area, the ipsilateral parasympathetics traveling in CN III, or the pupillary constrictor muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Accommodation (response to looking at something moving toward the eye)

A

Accommodation is impaired in lesions of the ipsilateral optic nerve, the ipsilateral parasympathetics traveling in CN III, or the pupillary constrictor muscle, or in bilateral lesions of the pathways from the optic tracts to the visual cortex. Accommodation is spared in lesions of the pretectal area.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Afferent pupillary defect

A
  • decreased direct response caused by decreased visual function in one eye when using the swinging flashlight test.
  • the affected pupil dilates in response to light.
  • Under normal conditions, the pupil constricts in response to light.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can block the pupillary reflex?

A

Alcoholism
Encephalitis
CNS syphilis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Extraocular Muscles

A 
-Medial and lateral recti
Move the eye from side to side
-Superior and inferior recti
Move the eye up and down
-Superior and inferior obliques
Rotate the eye around its optical axis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Oculomotor nerve (CN III)

A 
-Innervates the medical rectus
Turns the eye medially
-Innervates the superior rectus
Elevates the eye and rolls it upward
-Innervates the inferior rectus
Depresses the eye and rolls it downward
-Innervates the inferior oblique
Elevates the eye and turns it laterally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Trochlear nerve (CN IV)

A

Innervates the superior oblique and turns the eye downward and laterally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Abducens nerve (CN VI)

A

Innervates the lateral rectus and moves the eye laterally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Binocular fusion is controlled by

A

ocular reflex mechanisms that adjust the orientation of each eye to produce a single image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Conjugate gaze

A

Refers to the use of both eyes to look steadily in one direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Saccadic eye movements

A

Consists of small jumping movements that represent rapid shift in conjugate gaze orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Nystagmus

A

The sequence of SLOW ocular rotation, a saccade, slow rotation
Can be caused by lesions in the cerebellum and middle ear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the Lens

A
  • An avascular transparent biconvex body.
  • Posterior side is more convex than the anterior side.
  • Elastic capsule holds lens in place, allows lens to change shape.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe what happens to the lens for distant vision.

A

Sympathetic input relaxes the ciliary muscle, tightening the ciliary zonule, and flattening the lens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe what happens to the lens for close vision.

A

Parasympathetic input contracts the ciliary muscle, loosening the ciliary zonule, allowing the lens to bulge.

22
Q

When light rays strike an interface that is perpendicular to the beam

A

rays do not deviate from course

23
Q

What happens when light rays strike an interface that is angulated?

A

the rays bend. The amount the rays bend depend the difference between the refractive indices of the respective mediums. The greater the difference in refractive index, the more the ray will bend

24
Q

Convex Lens

A

At the center, the light ray will strike perpendicular and therefore will NOT diverge
The further from the center, the more the angulation… and therefore with a perfect convex lens all of the rays can be focused (convergence) on one spot (focal point)
Bending occurs both:
As the rays enter the lens
As the rays exit the lens

25
Q

Concave Lens

A

At the center, the light ray will strike perpendicular and therefore will NOT diverge
The further from the center, the more the angulation… and therefore the more the rays spread apart (divergence)
Bending occurs both:
As the rays enter the lens
As the rays exit the lens

26
Q

Focal Point

A

the point at which rays of light meet after passing through a lens

27
Q

Focal Length

A

the distance from the optical center of the lens to the focal point

28
Q

What controls the ciliary muscle?

A

The ciliary muscle is controlled almost entirely by parasympathetic nerve signals transmitted to the eye through the third cranial nerve (CN III).

29
Q

What are the two separate sets of smooth muscle fibers that make up the ciliary muscle?

A

Meridional fibers

Circular fibers

30
Q

Describe what happens to the lens during accommodation.

A
  1. Parasympathetic nerve signal
  2. Contraction of ciliary muscle fibers
  3. Relaxation of lens ligaments
  4. Lens Assumes a More Spherical Shape
  5. INCREASED Refractive Power
  6. Ability to Focus On NEARER Objects
31
Q

Emmetropia

A

a fancy word for “normal vision”
When parallel light rays from distant objects are in sharp focus on the retina when the ciliary muscle is completely relaxed. Eye must contract ciliary muscle to accommodate for objects at close range

32
Q

Presbyopia

A

“old eyes.” Lens grows larger, thicker, and becomes less elastic. Ability of the lens to change shape decreases. Power of accomodation decreases to almost 0 diopters by the age of 70

33
Q

Hyperopia

A

(Farsightedness). Eyeball is too short so focal point is behind the retina. capable of focusing distant objects on the retina

34
Q

Myopia

A

(Nearsightedness). Eyeball is too long so focal point in front of retina. YOU CAN’T RELAX THE CILIARY MUSCLE ANY MORE TO EXTEND THE FOCAL POINT BACK ANY FURTHER!! BUT, when an object comes nearer, it finally gets close enough that its image can be focused

35
Q

Astigmatism

A

when the image in one plane focuses at a different distance from that of the plane at right angles
Because accomodation manipulates the entire egg, no degree of accomodation can correct for the refractive error. the golfball (normal lens) versus the egg (astigmatic lens)

36
Q

Rods

A

Black and white

37
Q

Cones

A

Color

38
Q

Cone receptors

A

selectively sensitive to different wavelengths of light provide the basis for color vision.

39
Q

Cone color systems

A

Three types of cones, respond to the blue, green and red portions of the visible electromagnetic spectrum. depends on which set of cones or combination of sets of cones is stimulated in given image

40
Q

Color Blindness

A

Genetic defect in one or more of the three color cone mechanisms. Usually partial but can be complete.

41
Q

Interesting facts about color blindness

A

Males are more frequently affected with red, green, or red-green color-blindness. Disease of the more peripheral retina affects blue. Disease of the more central retina affects red and green because blue cones are not present in the central fovea

42
Q

What three factors are involved with depth perception?

A

Sizes of the images of known objects
Phenomenon of moving parallax
Phenomenon of stereopsis (binocular vision)

43
Q

Describe how the sizes of the images of known objects affects depth perception.

A

If you know the person is 6 feet tall, you can tell how far away they are simply by the size of that person on the retina

44
Q

Describe how a moving parallax affects depth perception

A

Relative distances of different objects can be determined by the extent with which they move when a person moves his or her head to one side or the other
Images close by - Move rapidly across retina
Images far away - No perceptible movement or very slowly

45
Q

Describe how stereopsis affects depth perception.

A

Binocular Vision
The distance of an object will determine the relative locations on the retina for each eye
The closer, the further separated on the retina

46
Q

Glaucoma

A

One of the most common causes of blindness
Disease in which the intraocular pressure becomes pathologically high
Pressures of 25-30 mm Hg for long periods can lead to loss of vision. Can rise to 60-70mm Hg.
In most cases, this results from increased resistance to fluid outflow through the trabecular spaces into the canal of Schlemm

47
Q

Glaucoma treatment

A

decrease secretion or increase absorption (if this fails there are surgical techniques to facilitate fluid flow)

48
Q

Optic Chiasm

A

The two optic nerves meet and fuse at the optic chiasm.
Optic nerve travels to the optic chiasm located just in from and below the pituitary gland.
At the chiasm optic nerve fibers from the nasal half of each retina cross over to the other side.

49
Q

Optic tracts

A

Axons from the nasal retina of each eye cross to the opposite side and join the axons of the temporal retina of the contralateral eye to form the optic tracts.
One tract contains fibers from both eyes that transmit info from the same visual field.
Nerve fibers originating the temporal retina do not cross over.

50
Q

Nerve Pathways

A

Visual info is carried to the brain by axons of the retinal ganglion cells, which form the optic nerve.

The optic nerve represents an outgrowth of the brain rather than a peripheral nerve

Exiting the optic globe and the orbit through the optic foremen, traverse the floor of the middle fossa to the optic chiasm at the base of the brain.

51
Q

Where is the Visual Cortex located?

A

In the Occipital lobe

Opthalmology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions