Chapter 5-Optics And Refractive States Of The Eye

Question 0

Physical Optics

Answer 0

The study of optics that describes the nature of light in terms of its wave properties.

Question 1

Optics

Answer 1

The branch of physical science that deals with the properties of light and vision.

Question 2

Geometric Optics

Answer 2

The area of optics that deals with the transmission of light as rays and is concerned with the effect of lenses on light and the production of images.

Question 3

Electromagnetic Radiation

Answer 3

Radiation produced through the combination of electrical and magnetic forces; includes rays from the shortest to longest wavelengths.

Question 4

Opaque

Answer 4

Refers to a substance that completely blocks light.

Question 5

Translucent

Answer 5

Refers to a substance that transmits light but significantly interferes with its passage.

Question 6

Transparent

Answer 6

Refers to a substance that permits the passage of light without significant disruption.

Question 7

Refracted

Answer 7

Refers to the change in directions of a light ray when it passes from one medium to another.

Question 8

Optical density

Answer 8

A lens property that increases the effectiveness to bend light.

Question 9

Refractive Index

Answer 9

The ratio of the speed of light in a vacuum to its speed through a specific substance.

Question 10

Prism

Answer 10

A triangular piece of glass or plastic with flat sides, an apex, and a base.

Question 11

Plane

Answer 11

Flat

Question 12

Apex

Answer 12

The top, as of a prism.

Question 13

Base

Answer 13

The bottom, as of a prism.

Question 14

Converge

Answer 14

To come together.

Question 15

Diverge

Answer 15

To spread apart.

Question 16

Convex Lens

Answer 16

A piece of glass or plastic in which one or both surfaces are curved outward. Also called a positive lens or plus lens.

Question 17

Concave Lens

Answer 17

A piece of glass or plastic which or both surfaces are curved inward. Also called negative lens or minus lens.

Question 18

Parallel

Answer 18

Refers to rays that travel side by side in the same direction, neither diverging nor converging.

Question 19

Principal Axis

Answer 19

The pathway of a light ray that strikes the center of a lens of any shape and passes undeviated through the lens material.

Question 20

Axial Ray/Principal Ray

Answer 20

A light ray that strikes the center of a lens of any shape and passes undeviated through the lens material.

Question 21

Paraxial Ray

Answer 21

Light rays that enter a lens system away from the center.

Question 22

Focal Point

Answer 22

The point somewhere along the principal axis at which the paraxial rays from a distant source are refracted by a lens and converge in the case of a convex lens and diverge in the case of a concave lens.

Question 23

Virtual image

Answer 23

The image formed by a concave lens when the paraxial rays from a distant source are refracted and diverge.

Question 24

Vergence Power/Power

Answer 24

The measure of a lens’s ability to converge or diverge.

Question 25

Focal Length

Answer 25

The distance between the focal point and the lens.

Question 26

Diopter

Answer 26

The unit of measure of the power of a lens.

Question 27

Accommodation

Answer 27

The change in the curvature of the crystalline lens that helps to focus images of objects close to the eye.

Question 28

Refractive State

Answer 28

The relative ability of the refractive components of the eye to bring objects into focus on the retina.

Question 29

Emmetropia

Answer 29

The refractive state of an eye that is able to focus correctly without the need for optical lenses.

Question 30

Ametropia

Answer 30

The refractive state of an eye that is unable to focus correctly due to a refractive error.

Question 31

Refractive Errors

Answer 31

A nonpathologic deficiency in the eye’s optical system.

Question 32

Presbyopia

Answer 32

The progressive loss of the accommodative ability of the lens, due to natural processes of aging.

Question 33

Myopia

Answer 33

Nearsightedness. If the eye is too long for its optical system the condition is called axial myopia. If the refractive power is excessive for the length of the eye, the condition is called refractive myopia.

Question 34

Spherical Cornea

Answer 34

A cornea (of the normal eye and most myopic and hyperopia eyes) whose curvature is uniform.

Question 35

Toric Cornea

Answer 35

A cornea whose surface curvature is not uniform.

Question 36

Astigmatism

Answer 36

The refractive error of an eye whose corneal surface curvature is greater in on meridian than another, both distant and near objects appear blurred and distorted.

Question 37

Principal Meridians

Answer 37

The meridians of maximum and minimum corneal curvature.

Question 38

Regular Astigmatism

Answer 38

The most common form of astigmatism, in which the cornea resembles a football standing on one end or on it’s side.

Question 39

Irregular Astigmatism

Answer 39

The less common form of astigmatism, in which the corneal surface loses its uniformity secondary to scarring or other pathology.

Question 40

Hyperopia

Answer 40

Farsightedness. If the eye is too short for its optical system the condition is called axial hyperopia. If the refractive power is insufficient for the length of the eye the condition is called refractive hyperopia.

Question 41

Spherical Lens/Sphere

Answer 41

A concave or convex lens whose curvature is uniform, allowing it to focus light rays to a single point.

Question 42

Bifocals

Answer 42

A lens with two visual purposes; commonly the correction of both distance and near vision.

Question 43

Trifocals

Answer 43

One that has three powers: one for correcting distance vision, one for correcting intermediate range of sight, and one for correcting near vision.

Question 44

Multifocal Lens

Answer 44

Bifocal lens/Trifocal lens

Question 45

Add

Answer 45

The portion of the multifocal lens (usually the lower part) that provides correction for near vision.