Vision Physiology I

Question 1

Light speed _____ when it passes through a transparent substance

Answer 1

Light speed decreases when it passes through a transparent substance

Question 2

REFRACTIVE INDEX (RI) is the ratio of the speed of light in _____ to the speed of light in the _____

Answer 2

REFRACTIVE INDEX (RI) is the ratio of the speed of light in air to the speed of light in the substance

Question 3

žAn angulated interface with different refractive indices causes _____ of light

Answer 3

žAn angulated interface with different refractive indices causes bending of light

Question 4

žThe ____ of _______ increases as the difference in RI increases and the degree of angulation increases

Answer 4

žThe degree of refraction increases as the difference in RI increases and the degree of angulation increases

Question 5

žThe light rays are eventually focused on the _____.

Answer 5

žThe light rays are eventually focused on the retina

Question 6

______ lens causes converging of light rays

Answer 6

convex lens causes converging of light rays

Question 7

In a convex lens, lightrays begin to bend in the _____ and

converge at the ____ _____.

Answer 7

In a convex lens, lightrays begin to bend in the periphery and

converge at the focal point.

Question 8

A _____ lens causes diverging of light rays.

Answer 8

A concave lens causes diverging of light rays.

Question 9

Refractive power is measured in ______

Answer 9

diopters

Question 10

The ______ the diopter, the ______ the lens is able to bend light rays to a simple____ ____.

Answer 10

The greater the diopter, the greater the ens is able to bend light rays to a simple focal point.

Question 11

Which lenses are more likely to be measured in diopters?

Answer 11

Convex lenses

Question 12

What structure of the eye has the greatest refractive power?

Answer 12

the cornea

Question 13

What tells you more about refractive power, the intrinsic refractive power value or the difference between refractive power values?

Answer 13

the difference between refractive power values

Question 14

What is the refractive power of the lens?

Answer 14

20 diopters

Question 15

_______ is the ability of the lens to change shape and become fatter or flatter.

Answer 15

accomodation

Question 16

Why is accomodation necessary?

Answer 16

žto focus the image on the retina

Question 17

On the retina, the image is ____ and ____.

Answer 17

inverted and reversed

Question 18

Relaxed lens is almost _____ in shape

Answer 18

Relaxed lens is almost spherical in shape

Question 19

Lens held in place by _____ _____ that cause the lens to be _____ under normal resting conditions

Answer 19

Lens held in place by suspensory ligaments that cause the lens to be flat under normal resting conditions

Question 20

_____ pulls ligament forward relaxing tension on suspensory ligament making the lens _____

Answer 20

Contraction pulls ligament forward relaxing tension on suspensory ligament making the lens fatter

Question 21

refractive power is greater when ciliary muscles are _____and lens is ____

Answer 21

refractive power is greater when ciliary muscles are contracted and lens is fatter

Question 22

Ciliary muscle controlled by _____ nerve signals

Answer 22

Ciliary muscle controlled by parasympathetic nerve signals

Question 23

When a person looks at an object in the distance, do the ciliary muscles need to contract?

Answer 23

no

Question 24

For near vision, the ciliary muscles ____and the central lens thickness ____to increase its power.

Answer 24

For near vision, the ciliary muscles contract and the central lens thickness increases to increase its power.

Question 25

Presbyopia:

žInability to _____

_____ of the proteins of the lens

žLens less ____

Answer 25

Presbyopia:

žInability to accommodate

žDenaturation of the proteins of the lens

žLens less elastic

Question 26

hyperopia

accommodate to see ____ objects.

eyeball too ____ or refractive power of lens is too ____

the focal point goes ____ _____ _____

Answer 26

hyperopia

accommodate to see far objects.

eyeball too short or refractive power of lens is too small.

the focal point goes beyond the retina

Question 27

myopia

when eyeball is too _____ or too ____refractive power in the lens.

Focal point is ____ ____ ____.

Answer 27

myopia

when eyeball is too long or too much refractive power in the lens.

Focal point is before the retina.

Question 28

Myopia corrected with _____ lens

Answer 28

Myopia corrected with concave lens

Question 29

Hyperopia corrected with _____ lens

Answer 29

Hyperopia corrected with convex lens

Question 30

Astigmatism causes a change in the ____ of light.

Answer 30

angulation

Question 31

Cataracts are characterized by a cloudy or _____area of the ____caused by the ____ of lens proteins

Answer 31

Cataracts are characterized by a cloudy or opaque area of the lens caused by the coagulation of lens proteins

Question 32

Visual Acuity

____ or _____ of vision

žAbility to perceive ____ _____

žDiscern letters or numbers at a given distance (____ feet)

Answer 32

Visual Acuity

Clarity or sharpness of vision

žAbility to perceive small details

žDiscern letters or numbers at a given distance (20 feet)

Question 33

Motion parallax: a ____ depth cue in which we view objects that are closer to us as moving ____ than objects that are further away from us.

Answer 33

Motion parallax: a monocular depth cue in which we view objects that are closer to us as moving faster than objects that are further away from us.

Question 34

stereopsis: you can see with ____ eyes better than you can see with____

Answer 34

stereopsis: you can see two eyes better than you can see with one

Question 35

Intraocular fluid keeps the eyeball ____ and _____.

Answer 35

Intraocular fluid keeps the eyeball round and distended

Question 36

2 types of intraocular fluid:

1. ______ humor: freely flowing fluid
2. _____ humor: Gelatinous mass with little flow of fluid

Answer 36

2 types of intraocular fluid:

1. Aqueous humor: freely flowing fluid
2. Vitreous humor: Gelatinous mass with little flow of fluid

Question 37

Formation of aqueous humor:

• Produced by ___ ______ of the ____ ____ at a rate of 2-3 microliters/min
• Aqueous humor formed by ____ _____ of ____ _____
• Active transport of ___ followed by ____ and ____
• Water follows by ________

Answer 37

Formation of aqueous humor:

• Produced by ciliary processes of the ciliary body at a rate of 2-3 microliters/min
• Aqueous humor formed by active secretion of ciliary processes
• Active transport of Na+ followed by Cl- and HCO3-
• Water follows by osmosis

Question 38

Outflow of aqueous humor from the eye:

Flow of aqueous humor through the ___ into the _____ ____ of the eye

Fluid flows _____ to the ____ and into the angle between the ____ and ____

____ __ _____ and into the _____ __ ____which empties into ______ _____.

Answer 38

Outflow of aqueous humor from the eye:

Flow of aqueous humor through the pupil into the anterior chamber of the eye

Fluid flows anterior to the lens and into the angle between the cornea and iris

Meshwork of trabeculae and into the canal of schlemm which empties into extraocular veins

Question 39

Intraocular pressure measures how quickly the flow of ____ ____ enters ____ __ ____.

Answer 39

Intraocular pressure measures how quickly the flow of aqueous humor enters canal of schlemm

Question 40

Intraocular pressure is žnormally __mmHg with a range of 12-20 mmHg

Answer 40

Intraocular pressure is žnormally 15 mmHg with a range of 12-20 mmHg