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NCLE > Introduction to Contact Lenses > Flashcards

Introduction to Contact Lenses Flashcards

1
Q

What year was the first contact lens manufactured?

A

1887

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2
Q

Who manufactured the first contact lens, and what was its purpose?

A

F.A. Muller, a bandage contact for a diseased portion of the eye

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3
Q

What was the first contact lens made out of?

A

Glass

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4
Q

Who created the first true refractive contact lens?

A

A.E. Fick

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5
Q

When was the first corneal contact lens created?

A

1948

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6
Q

Who was the first to create a corneal contact lens based on K readings?

A

George Butterfield

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7
Q

Why was George Butterfield’s discovery important for contact lens fitting?

A

It invented the modern concept of “fitting on K’s”, and he discovered that this helped the contact have a better fit on the cornea.

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8
Q

When was the first successful hard contact lens developed?

A

1955

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9
Q

What did Otto Whichterle and Drahslav Lim invent?

A

A hydrogel material for contact lenses, which had poor optics but created greater comfort for wearers. This material was later called HEMA

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10
Q

When did the FDA start regulating contact lenses?

A

1968

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11
Q

What were the first contact lenses that were approved by the FDA?

A

Bausch and Lomb Soflens

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12
Q

When was the first gas permeable lens approved by the FDA?

A

1979

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13
Q

When were the first extended wear soft contact lenses approved by the FDA?

A

1981

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14
Q

When did J&J release their first disposable contact lenses?

A

1987

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15
Q

What were gas permeable lenses made out of in 1987?

A

Flourosilicone Acrylates: the flourine combined with the silicone helps to improve wettability and maintains high oxygen transmission.

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16
Q

Who was the first daily disposable contact lens invented by? and what was it called?

A

Ron Hamilton, it was called soflens 1 day

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17
Q

The first daily disposable was released by J&J in what year?

A

1996

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18
Q

What was the first silicone hydrogel lens that Bausch and Lomb developed?

A

Purevision

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19
Q

When was overnight orthokeratology approved by the FDA?

A

2002

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20
Q

Scleral Lens: Sizes

A

14.5-18mm is a mini scleral, and 18.5-24mm is a scleral

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21
Q

How do scleral lenses sit on the cornea?

A

Scleral lenses cover the entire cornea. They effeciently use tear film to correct and defects within the cornea.

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22
Q

Corneal Lens: Size

A

7.4mm to 9.2mm

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23
Q

How do corneal lenses sit on the cornea?

A

They cover 75-80% of the cornea, and is the most common gas permeable lens.

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24
Q

Corneal-Scleral Lens Size and Importance

A

13-55mm in diameter, used to bridge the gap between the corneal and scleral size.

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25
Q

What are corneal-scleral lenses frequently used for?

A

These lenses are used frequently for irregular corneal astigmatism. Larger diameters are used for advanced keratoconus and chronic dry eye resulting in scarring and other corneal defects.

26
Q

Semi-Scleral Contact design

A

Soft contact lens design, it covers the entire cornea, limbus, and part of the sclera

27
Q

Hybrid Lens Design

A

It is a corneal gas permeable lens with a soft skirt, combines the visual clarity of a GP with the initial comfort of a soft lens. Fitting diameter is similar to a semi scleral.

28
Q

PMMA Polymethylmethacrylate

A

Developed by Kevin Touhey in 1947, it is used for a conventional hard lens.

29
Q

Advantages of PMMA

A

Easily fabricated, corrects up to 3 diopters of corneal astigmatism, little fluctuation in vision due to lens flex, and they are very durable.

30
Q

Disadvantages of PMMA

A

Hydrophobic, poor gas permeability, corneal edema is common from wear, and poor patient comfort.

31
Q

CAB-Cellulose Acetate Butyrate

A

Contact lens material that was first developed for photographs by Eastman Kodak, it was first used in contact lenses in 1974.

32
Q

Advantages of CAB

A

Greater patient comfort, difficult to break, less risk of edema, elimination of edge flair, and durability.

33
Q

Disadvantages of CAB

A

Material warps with wear and overtime, and thickness reduces the warpage but increases patient awareness.

34
Q

Silicone Acrylate

A

Developed in 1979 by Syntex Opthalmics. Made up of 35% silicone and 65% PMMA.

35
Q

Clinical names for silicone acrylate

A

Polycon I and II, Boston II and IV, and Paraperm 02 and EW

36
Q

Advantages of Silicone Acrylate

A

High oxygen permeability, can be manufactured very thin, and are flexible. It also has greater patient comfort then previous materials.

37
Q

Disadvantages of Silicone Acrylate

A

Attracts proteins and lipids

38
Q

Base Curve

A

Radius of curvature on the back central surface of a contact lens.

39
Q

Blend Curve

A

Treatment given to the sharp junction between the secondary and peripheral curve to eliminate sharp edges due to abrupt changes in curvature. This is typically equal to the average radii of the secondary and peripheral curve.

40
Q

Peripheral Curve

A

Outermost curve on the back surface of the lens that is designed to prevent the lens from pressing on the limbal area of the curve and enables it to move when the eye blinks

41
Q

Center Thickness

A

The distance at the geometric center from the back surface to the front surface

42
Q

Diameter

A

Overall width of the lens from one end to the other, at its widest point, measured in mm

43
Q

Optical Zone

A

Diameter on which the base curve extends on the back surface of the lens

44
Q

Anterior Optical Zone

A

A curvature on the front surface that gives a contact lens its power, also called a lenticular cap.

45
Q

Back Surface Toric Lens Design

A

Spherical front design but the back surface has toric curves at the major meridians 90 degrees apart.

46
Q

Bitoric Lens Design

A

Toric curves at the major meridians 90 degrees apart, on both the front and back surfaces of the lens

47
Q

Front Surface Toric Lens Design

A

Spherical back surface with toric curves on the front surface of the lens.

48
Q

“K”

A

The flattest meridian as determined by keratometry

49
Q

Lenticular Flange

A

A deliberate thickening or thinning of a lens edge

50
Q

An increase in edge thickness would:

A

Aid in lens centering, if the lens sits low on the cornea because it raises the lens, known as myoflange.

51
Q

A decrease in edge thickness would:

A

Good for high minus lenses because it limits lid interaction or to lower a high riding lens, known as hyperflange

52
Q

To increase edge thickness:

A

Order a flatter radius in relation to base curve

53
Q

To decrease edge thickness:

A

Order a steeper radius in relation to the base curve

54
Q

Lens Edge

A

Junction between the front and back surfaces of the lens

55
Q

Anterior Zone

A

Touches the lid and it is designed to minimize lid irritation.

56
Q

Posterior Zone

A

Small reverse curve on the back surface to push edge away from the surface of the eye, helps maintain centration and allows movement of the lens during blinking.

57
Q

Apex

A

Where two zones meet and should be sufficiently rounded

58
Q

Lens Power

A

Measured as the difference between the radii of the front and back surfaces

59
Q

Prism Ballast

A

Larger addition to base down prism to the bottom of the lens that helps orient position for specialty lenses such as translating bifocal designs or toric lenses

60
Q

Saggital Depth

A

Distance from a flat surface and the central back surface of the lens

61
Q

Spherical Curves

A

Radius of curvature is the same along every meridian along the back and front surface of the lens

62
Q

Truncation

A

Removal of a portion of the lens so that it can aid in orientation. Good for front toric and bifocal toric lens designs.

NCLE (2 decks)

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