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Paraoptometric CPO Study Guide/Terms > Eyeglasses - Ophthalmic Optics And Dispensing > Flashcards

Eyeglasses - Ophthalmic Optics And Dispensing Flashcards

(65 cards)

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1
Q

Optics

A

The scientific study of sight and the behavior of light

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2
Q

Plus Lenses/ Convex

A

Lens is thick in the center and
thin on the edge.

-Used to correct hyperopia and presbyopia.

-Objects viewed through this lens will appear larger/ magnified

-Light rays passing through will be converged/ brought closer together.

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3
Q

Minus Lenses/Concave

A

Lenses are thin in the center and thick on the edges. Objects viewed through a minus lens will appear smaller, or minified. Light rays passing through a minus lens will be diverged, or moved apart. Minus lenses are used to correct myopia.

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4
Q

What Are The Two Lens Types?

A

-Plus/ Convex
-Minus/Concave Lense

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5
Q

Spherical Lens

A

Deviates rays of light in the same direction. A lens that has one curve. (Ex: -1.00 OU has myopia both eyes without astigmatism or +1.00 OU has hyperopia both eyes no astigmatism)

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6
Q

Cylindrical Lens

A

Deviates rays of light in more than one direction. (Ex: –1.00 –0.75 x 180 OU has myopia in both eyes with astigmatism positioned at 180 degrees)

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7
Q

Components of Lens Prescription

A

1.) Sphere- first number listed indicates how much myopia or hyperopia the patient has.
2.) The cylinder- second number listed indicates the amount of astigmatism the patient has.
3.)The axis- last/third number preceded by “X”. It is the position of astigmatism anywhere from 1 to 180 degrees.

Last component is add power if progressive Rx.

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8
Q

What is lowest sphere power?

A

0.25 diopters (+ or -)

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9
Q

What is lowest Add Power?

A

+ 0.25 diopters

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10
Q

What is add power?

A

Additional plus power people need to view things at near and arm’s length distance. The near viewing is done by using multi-focals (bifocals, trifocals, progressive addition lenses).

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11
Q

What is a prism?

A

A transparent wedge shape (similar to pyramid) that displaces rather than focuses light.

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12
Q

What is the top of a prism called?

A

Apex

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13
Q

What is the bottom of a prism?

A

Base

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14
Q

What is prisim power measured in?

A

Diopter. One prism diopter will bend a ray of light 1 centimeter for every 1 m of distance.

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15
Q

What does a Lensometer measure?

A

-Measures the sphere power
-cylinder power
-the cylinder axis of the lens
-the amount of prism in the lens,
-the base direction of the prism
-the powers of the multi-focal lenses

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16
Q

What are 5 types of Eyeglass Lens materials?

A

1.) Glass
2.) Plastic (CR-39)
3.) Polycarbonate
4. Trivex
5.) High-Index Lenses

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17
Q

Crown Glass Lens Material

A

Hardest surface, therefore the most scratch-resistant. Best optics.

But easiest to break or shatter, heavy.

Refractive Index: 1.5

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18
Q

Plastic (CR-39) Lens Material

A

-Less scratch-resistant (can be treated to be more scratch resistant)
-thicker than glass, but less likely to break or shatter.
-lightweight
-tint easily
-great optics

Con: not impact resistant

Refractive Index: 1.5

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19
Q

Polycarbonate Lens Material

A

-Less scratch-resistant (always treated for scratch-resistance)
-Much harder to break or shatter
-Used as safety lens for children, athletes, and monocular patients. -Thinner than glass or CR-39 lenses
-Lightweight

Con: Doesn’t tint, has distortions and aberrations in lens.

Refractive Index: 1.6

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20
Q

Trivex Lens Material

A

-Less scratch resistant (always treated for scratch-resistance)

-thinner than glass or CR-39, but slightly thicker than polycarbonate. -

-Used as safety lens for all children, athletes, and monocular patients.

-Free from distortions and aberrations.

-Impact resistant

-lightweight

-great optics

-tints easily.

Refractive Index: 1.5

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21
Q

High-Index Lens Material

A

These are the thinnest lens materials and thus provide a better cosmetic appearance for eyeglasses in higher prescriptions.

Con: optical quality reduced and not impact resistant

Refractive Index: 1.6-1.7

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22
Q

What are the 5 Lens coatings?

A

1.) Scratch-resistance
2.) Anti-reflective
3.) Ultraviolet
4.) Mirror
5.) Sports

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23
Q

Scratch-Resistance Coating

A

Layer of resin that protects the lens from many surface scratches

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24
Q

Anti-Reflective Coating

A

-Increase visual acuity because they eliminate internal lens reflections.
-Reduction of glare at night/in dim light
-More visibility of the wearer’s eyes to observers, playing sports, and using a computer.
-It allows all the light to pass through the lens so the light doesn’t get trapped on the lens which causes the glare spots.

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25
Ultraviolet Coating
Filters out UV light and protects the eye from potentially damaging UV light both indoors and outdoors.
26
Mirror Coating
Reflects some of the light striking the lens and increasing the density of the lens
27
Sports Coating
Improve contrast sensitivity and reduce glare
28
Zyl/ Acetate Frames
Plastic frame. -Made of rugged polymers that are most common frame material. -Lightweight -easily adjustable -comes in many colors.
29
Metal Frames
-Front and temples comprised of metal. -Adjusting frames usually requires special pliers and other tools. -Lenses usually held in place by an eyewire that is tightened with a screw to hold it in place. Pro: Very adjustable
30
Flexon Frames
Titanium based alloy. Referred to as memory metal because of ability to come back into shape even after being twisted, bent or crushed. -lightweight -hypoallergenic -corrosion resistant. Con: Expensive
31
What is the first and most important step of frame selection?
Patient’s Prescription
32
Rules for proper fit
1.) Width of frame- approximately equal to the width of the patient’s face. 2.) Bridge of frame- Should rest flat on the sides of the nose. 3.)Temple length- Should be long enough to extend over the patient’s ear and far enough beyond to balance the weight of the front of the frame.
33
Frame Fit for Longer Face
Greater the vertical depth of the frame should be.
34
Frame Fit for Shorter Face
Smaller the vertical depth of the frame should be.
35
What is the Cosmetic Criteria for Frame Fit?
Upper eyewire of the frame should contour the shape of the patient’s eyebrow. Goal is to balance the features of the face. To minimize the features of a round or square face shape, fit a frame that has the opposite features
36
Pupillary Distance (PD)/ Interpupillary Distance
Distance between the centers of the pupil of each eye. Reason for taking the patient’s P.D. is because the center of the lens sits directly in front of the center of the patient’s eyes. The P.D. can be obtained using a millimeter ruler or a pupilometer.
37
Steps to Measure PD
1.) Focus on area being measured which is the distance between the centers of the pupil of each eye. 2.) Face the patient about 40 centimeter distance between examiner and the patient. 3.) Place a millimeter rule resting on the patient’s nose. 4.) Have patient look at your open left eye, while closing your right eye 5.) Line up zero point of rule with temporal edge of patients right pupil 6.) Ask patient to look at your open right eye (while you close your left eye). 7.) Reading is taken from the rule, where it aligns with the nasal edge of the patient’s left pupil. Record that number. *If it is hard to see the edge of the patient’s pupil, because of a dark iris, use the temporal edge of the limbus of the right eye and the nasal limbus of the left eye.
38
Required Elements To Order Eyeglasses
1.) Frame color 2.) Eyesize 3.) Bridge size 4.) Temple length. 5.) Specify the prescription for the lenses in each eye 6.) P.D. at far and near (when applicable) 7. Lens design (single-vision, bifocal style, etc.) 8.) Lens material 9.) seg height (if not single- vision), 10.)Any tints or coatings that should be used.
39
Four Types of Eyeglass Lenses
1.) Single-vision 2.) Bifocal 3.) Trifocal 4. Progressives
40
Categories of Eyeglass Frames
1.) Full Frame 2.) Semi-rimless 3.) Rimless
41
Single-vision
Used to correct a single vision problem such as nearsightedness, farsightedness, astigmatism. (Ex: Distance only, Reading only)
42
Bifocals
Has two distinct optical powers distinguished with a line between the two regions. Commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism
43
Trifocals
-Lenses that have three optical zones -correct for distance, intermediate, and near vision. -Visible lines in between regions. Mostly used by people with advanced presbyopia who have been prescribed 2 diopters or more of reading addition.
44
Progressives
-Three optical zones -correct for distance, intermediate and near vision -No visible line in between regions. Allows wearer to more seamlessly transition to each optical zone.
45
What is a prism Lens?
Lens that displaces light rather than focuses light
46
What is best Indicator of Well Fitting Frame?
A well centered eye. If too big will cause the eyes to be positioned to near the bridge of the frame. If too small will cause the eyes to be positioned to near the outer portion of the frame.
47
Frame Bridge Types
1.) Saddle- Most common. For best fit it should be like a saddle on a horse no gaps. 2.) Keyhole- Great for smaller noses. The smaller space between the lenses are the best point of contact. 3.) Low Bridge- Best plastic option for very small and flat bridges.
48
Photochromic Lens (Transitions)
-Lens darkens when exposed to UV light -In absence of activating light the lenses return to their clear state. -may be made of polycarbonate, or another plastic
49
Polarized Lenses
Minimize glare in bright, sunny, outdoor settings. Blocks light on a horizontal plane like a window blind.
50
Principles of Frame Selection
1.) Style 2.) Shape 3.) Type of Eyeglass Prescription
51
Refractive Index
How much light slows down as it passes through the lens.
52
Blue Light Protection
Filter added to a lens that blocks blue light given off by digital screens, glare protection, reduce damage to retina
53
Beryllium Frame
Type of metal frame. -lightweight -durable -flexible -extremely corrosion resistant. Cons: Expensive
54
Titanium Frame
Metal frame. -Lightweight -durable -hypoallergenic. Con: Expensive
55
Stainless Steel Frame
Metal frame. -Light to Medium Weight -durable -less expensive than titanium -hypoallergenic
56
Monel Frame
Metal frame. Inexpensive Con: Can cause allergic reaction.
57
Aluminum Frame
Metal frame. -Lightweight -durable -corrosion resistant -slightly flexible. Cons: Expensive
58
Nylon Frames
Plastic frame. -Lightweight -durable -good for sport and sunglasses.
59
Optyl Frames
Plastic/ Epoxy resin frame. -Very bendable -comes in translucent and opaque colors. -Important to let air dry after heating.
60
Pupilometer/ Pupillometer
Hand held instrument that measures pupillary distance (PD)
61
What is a Plano-Cylinder (Pl-Cylinder) Lens?
A lens where one part has no power and 90 degrees away there is power.
62
Sphero-Cylindrical Lens (Sph/Cylindrical)
A lens used to treat myopia/hyperopia and astigmatism.
63
Neutralizing lenses
Using lenses that are equal in magnitude but opposite in direction to neutralise the spectacles, so there is no overall effect. (Ex: +2.50 sphere in a spectacle lens is neutralised with a -2.50 spherical trial frame lens.) Generally start with right lens first, unless there is a notable difference in the powers of the left and right lenses (look at the thickness of the lenses) then choose the lens that is more powerful to neutralize first.
64
What is seg height for bifocal lenses?
Measurement from bottom most edge of lens to patient lower lid.
65
What is seg height for progressive lenses?
Measurement from bottom most edge of lens to center of patient pupil.

Paraoptometric CPO Study Guide/Terms (19 decks)

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