Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

COA Vocabulary > Chapter 5: Optics and Refractive States of the Eye > Flashcards

Chapter 5: Optics and Refractive States of the Eye Flashcards

1
Q

Optics

A

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

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

Physical Optics

A

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

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

Geometric Optics

A

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

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

Electromagnetic Radiation

A

Radiation produced through the combination of electrical and magnetic forces, includes rays from the shortest to the longest wavelengths, both visible and invisible

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

Opaque

A

Refers to a substance that completely blocks light from passing through it

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

Translucent

A

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

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

Transparent

A

Refers to a substance that transmits light without disrupting its passage

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

Refracted

A

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

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

Optical Density

A

A lens property that increases the effectiveness to bend light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Refractive Index

A

The ratio of the speed of light in a vacuum to its speed through a specific substance
Formula= Speed of light in vacuum divided by the speed of light in a specific substance

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

Prism

A

A triangular piece of glass or plastic with flat sides, an apex, and a base.
When light passes through a prism, it is bent in a different direction (towards the base)
Refractive power depends on refractive index and size of its apex angle. 1 prism D deviates light 1cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Plane

A

Flat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Apex

A

The top of the prism; pointed

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

Base

A

The bottom of the prism; wider

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

Converge

A

To come together

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

Diverge

A

To spread apart

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

Convex Lens

A

A piece of glass or plastic in which one or both surfaces are curved outward
Also called a Positive, or Plus Lens

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

Concave Lens

A

A piece of glass or plastic in which one or both surfaces curve inward
Also called a Negative Lens, or Minus Lens

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

Parallel

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Principle Axis

A

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

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

Principle Rays, Or Axial Rays

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Paraxial Rays

A

Light rays that enter a lens system away from the center
In Convex lenses, Paraxial rays are brought inward to converge at some point along the Principle Axis
In Concave lenses, Paraxial Rays diverge away from the Principle Axis, and instead produce a virtual image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Focal Point

A

The point somewhere along the principle 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Plus Lenses

A

Also called a Convex Lens, or Positive Lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Minus Lenses
Also called Concave Lenses or Negative Lenses
26
Virtual Image
The image formed by a concave lens when the paraxial rays from a distant source are refracted and diverge
27
Vergence Power
Also called Power, it is the measure of a lens' ability to converge or diverge light rays
28
Focal Length
The distance between the focal point and the lens
29
Diopters
The unit of measurement of Power of a lens D=1/f (focal length)
30
Accommodation
The change in the curvature of a crystalline lens that helps to focus images of objects close to the eye
31
Refractive State
The relative ability of the refractive components of the eye to bring objects into focus on the retina
32
Emmetropia
The refractive state of the eye that is able to focus correctly without the need for corrective lenses
33
Ametropia
The refractive state of the eye that is unable to focus correctly due to a refractive error and requires corrective lenses
34
Refractive Error
A nonpathological deficiency in the eye's optical system
35
Presbyopia
The progressive loss of Accommodation, due to again
36
Myopia
Nearsightedness=able to see close, but not far away Light rays are focused in front of the retina (too much plus power) Requires Concave lenses to correct
37
Hyperopia
Farsightedness= able to see far away, but not close Light rays are focused behind the retina (too much minus power) Requires Convex lenses to correct
38
Astigmatism
The refractive error of the eye whose corneal surface curvature is greater in one meridian than another Both distant and near objects will appear distorted
39
Spherical Cornea
A cornea whose curvature in all meridians is uniform
40
Toric Cornea
A cornea whose surface curvature is not uniform Light rays are not focused into a single point
41
Principal Meridians
The meridians of maximum and minimum corneal curvature, these meridians are at 90 degrees from each other
42
Regular Astigmatism
The most common form of astigmatism, in which the cornea resembles a football standing on one end of on its side
43
Irregular Astigmatism
The less common form of astigmatism, in which the corneal surface losses its uniformity secondary to scarring or other pathology
44
Types of Corrective Lenses
Glasses, contact lenses, refractive surgery, or surgical implantation of a corrective lens
45
Spherical Lens
A concave or convex lens whose curvature is uniform
46
Bifocals
A lens that has 2 powers, typically one for correcting distance vision and one for correcting near vision
47
Trifocals
A lens that has 3 powers: one for correcting distance vision, one for correcting intermediate vision, and one for correcting near vision
48
Multifocal Lenes
Any lens that has more than one power
49
Add
The portion of the multifocal lens that provides correction for near vision
50
Cylindrical Lenses
A lens that has curvature in only one meridian, commonly used to help correct Astigmatism
51
Axis
The meridian perpendicular to the meridian with the curvature in cylindrical lens
52
Spherocylinder Lens
A combination of spherical and cylindrical lenses Also called a Toric Lens Does not refract light rays into a single point, but into 2. The clearest point is called the Circle of Least Confusion
53
Toric Lens
Also called a Spherocylinder Lens
54
Lensometry
The measurement of certain qualities of lenses by use of a lensometer
55
Refraction
The process of measuring a patient's refractive error. Combination of Refractometry and Clinical Judgement Steps: Retinoscopy, Refinement, Binocular balancing
56
Retinoscopy
The use of a Retinoscope to determine a refractive error 1st step in Reffraction
57
Refinement
The subjective 2nd step of Refraction, requiring patient participation and responses, which confirms the information produced with Retinoscopy Also called Subjective Refractometry or Manifest Refractometry
58
Binocular balancing
A procedure performed on both eyes at once to ensure that the optical correction determined by refractometry for distance vision does not include an uneven overcorrection or undercorrection
59
Cycloplegic Refraction
Refractometry performed with the use of a drug that temporarily paralyzes the ciliary muscle, thus blocking accommodation Done in children frequently
60
Manifest Refraction
Refractometry performed without the use of cycloplegic drugs
61
Objective Refractometry
Also called Retinoscopy
62
Retinoscope
A handheld instrument for measuring refractive error, consists of a light source and a viewing component, and is used in conjunction with a phoropter or trial lenses
63
Fixate
To gaze steadily at something
64
Plano Mirror Effect
The flat lighting effect of a retinoscope that produces slightly divergent rays
65
Concave Mirror Effect
The lighting effect of a retinoscope that produces convergent rays
66
With Motion
The retinoscopic reflex movement that is in the same direction as the movement of the streak of light from a retinoscope Typically seen in a Hyperopic eye
67
Against Motion
The retinoscopic reflex movement that is in the opposite direction from the movement of the streak of light from the retinoscope Typically seen in Myopic eyes
68
Neutralization Point
The lens power that is the approximate correction for a refractive error. This is the goal of Retinoscopy
69
Trial Lens Set
A set of various hand-held lenses introduced before a patient's eye to select the appropriate corrective lenses These lenses can be set into a trial frame set
70
Phoropter, or Refractor
An instrument for determining a corrective lens prescription; stores a range of trial lenses that can be dialed into position
71
Subjective Refractometry
Also called Refinement
72
Cross Cylinder
A special lens consisting of 2 cylinders of equal power, one minus and one plus, with their axes set at right angles to each other; used for determining the axis and power of an astigmatic correction
73
OD
Right eye (oculus dexter)
74
OS
Left eye (oculus sinister)
75
OU
Both eyes (oculus uterque)
76
Transposition
The conversion of a lens prescription from a plus-cylinder to a minus-cylinder Steps: 1. Algebraically add cylinder power to sphere power 2. Reverse sign of cylinder power 3. Add/Subtract 90 degrees from axis
77
Lensmeter
An instrument for measuring the prescription of glasses Also called Lensometer, Vertometer, or Focimeter Steps: 1. Focus eyepiece 2. Position lens on the stage 3. Measure sphere power (3 thin lines) 4. Measure cylinder power (3 thick lines)(Turn dial towards you for plus cylinder or away from you for minus cylinder) 5. Note axis 6. Measure multifocal power by repositioning glasses (thick to thick lines, or thin to thin lines) 7. Measure Prism (if present)
78
Vertometer
A device for measuring the distance between the posterior surface of the glass lens and anterior surface of the eyeball Also called Distometer
79
Keratometry
The measurement of corneal curvature
80
Keratometer, or Ophthalmometer
An instrument used to measure corneal curvature

COA Vocabulary (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions