UNIT FOUR - CL Characteristics/Manufacturing

Question 1

LENS CHARACTERISTICS:
Oxygen permeability (DK Value)

Answer 1

D= diffusion coefficient for oxygen movement in the lens material 
K= solubility of oxygen in the material

Question 2

LENS CHARACTERISTICS:
Oxygen transmissibility (DK/L)

Answer 2

D= diffusion coefficient for oxygen movement in the lens material 
K= solubility of oxygen in the material
L= lens thickness

Question 3

LENS CHARACTERISTICS:

Wettability

Answer 3

Wetting angle

Functional wettability

Question 4

LENS CHARACTERISTICS:

Heat transfer

Answer 4

………..

Question 5

LENS CHARACTERISTICS:

Stability

Answer 5

Flexure

Warpage

Question 6

LENS CHARACTERISTICS:

Durability

Answer 6

…………..

Question 7

LENS CHARACTERISTICS:

Deposit resistance

Answer 7

………………

Question 8

LENS CHARACTERISTICS:

Electrostatic properties

Answer 8

Ionic

Non-ionic

Question 9

LENS CHARACTERISTICS:

Reproducibility

Answer 9

……………

Question 10

Rigid lens materials (4 total)

Answer 10

Polymethylmethacrylate (PMMA)
Cellulose Acetate Butyrate (CAB)
Silicone Acrylate (SA)
Fluoride-Silicone Acrylate (FSA)

Question 11

Rigid lens designs (6 designs)

Answer 11

Spherical
Front surface toric
Back surface toric
Bitoric
Aspheric
Cosmetic

Question 12

RIGID LENS MANUFACTURING:

Lathe cut

Answer 12

Liquid monomers
Polymerization using heat & UV light
Base curve
Peripheral curves
Anterior curves
Edge

Question 13

RIGID LENS MANUFACTURING:

Cast molded

Answer 13

Base curve

Question 14

Soft lens materials (3 materials )

Answer 14

Hydroxyethylmethacrylate (HEMA)
Glyceryl Methylmethacrylate (GMMA)
Silicone Hydrogel

Question 15

Soft lens designs ( 7 total)

Answer 15

Spherical
Front surface toric
Back surface toric
Bitoric
Aspheric
Cosmetic
Therapeutic

Question 16

SOFT LENS MANUFACTURING:

Lathe cut

Answer 16

Liquid monomers
Polymerization using heat & UV light
Base curve
Peripheral curves
Anterior curves
Edge
Hydration
Extraction (rinsing)
Inspection

Question 17

SOFT LENS MANUFACTURING:

Spin cast

Answer 17

Liquid monomers 
Spinning molds of front surface 
Polymerization using heat&UV light
Edge
Hydration 
Extraction (rinsing)
Inspection

Question 18

SOFT LENS MANUFACTURING:

Cast molding

Answer 18

Liquid monomers
Concave&convex molds
Polmerization using heat&UV light
Edge
Hydration
Extraction (rinsing)
Inspection

Question 19

Manufacturing concerns

Answer 19

Lens design 
Material characteristics 
Production volume
Reproducibility 
Quality control

Question 20

Manufacturing costs

Answer 20

Research and development
Engineering and equipment
Materials
Labor

Question 21

Manufacturing methods (4 total)

Answer 21

Lathe cast
Spin cast
Spin cast/lathe cast
Cast molded

Question 22

Standard Lathe manufacturing process :

Posterior surface

Answer 22

Button mounting
Cutting central posterior curve
Polishing CPC or base curve
Generating secondary and peripheral curves

Question 23

CNC multi-Axis Lathe Manufacturing Process

Answer 23

Computer entry 
Network capabilities 
Base and peripheral curves 
Aspheric curves 
Toric curves 
Edge design

Question 24

Cast Molded Radius buttons

Answer 24

Liquid monomer
Polymerization in molds
Buttons with finished base curve


Question 25

Standard lathe manufacturing: | Anterior surface

Answer 25

Blocking Lathe anterior surface Edging

Question 26

What are the three parts that are needed to be inspected?

Answer 26

Base curve and surface quality Power Edge

Question 27

During the inspection process, base curve and surface quality can be inspected by what?

Answer 27

Radiuscope

Question 28

During the inspection process,power can be inspected by what?

Answer 28

Lensometer or auto lensometer

Question 29

During the inspection process, edge can be inspected by?

Answer 29

Projection magnifier

Question 30

What are some of the soft lens additional Procedures?

Answer 30

Hydration, extraction, tinting, wet inspection, final packaging, sterilization, and labeling.

Question 31

What are some of the contact lens packagings?

Answer 31

``` Vials(older design) Blister packs (current) ```

Question 32

What are some advantages of lathe cutting ?

Answer 32

Design options Material options Low volume production

Question 33

What are some disadvantages of lathe cutting?

Answer 33

Labor costs Material waste Reproducibility

Question 34

What was the original manufacturing process of contact lenses ?

Answer 34

Spin cast

Question 35

What are the steps of the Spin cast manufacturing process?

Answer 35

1) Stainless steel tools form molds 2) Mold place in spinning cavities in lens production table 3) Liquid monomer is injected into spinning, computer controlled mold 4) Lens form solidifies under UV light 5) Edge is trimmed and rounded 6) lens hydrated and rinsed

Question 36

What are some advantages of Spin cast manufacturing?

Answer 36

Unit cost Reproducibility Comfort

Question 37

What are some disadvantages of Spin cast manufacturing?

Answer 37

Cost of initial set up | Visual acuity 

Question 38

What is the most popular method of manufacturing today ?

Answer 38

Cast molding

Question 39

What is the process for cast molded manufacturing?

Answer 39

1) stainless steel tools form convex and concave plastic injection molds 2) reusable quartz molds may be used 3) concave mold is filled with liquid monomer 4) convex mold is placed on top and clamped 5) polymerization occurs as lenses are exposed to heat and UV light 

Question 40

What are some of the additional processes for Cast molding ?

Answer 40

Hydration, rinsing, tinting, surface treatment, wet inspection, packaging, and labeling 

Question 41

What are additional names for cast molding ?

Answer 41

Fully molded, light stream molded, stabilized soft molded, and wet molded.

Question 42



Question 43

What are some cast molded lens designs and types?

Answer 43

Frequent replacement, disposable, spherical, toric, and multifocal.

Question 44

What are some advantages of cast molded manufacturing?

Answer 44

Lower unit cost Surface quality Reproducibility

Question 45

What are some disadvantages of cast molded manufacturing?

Answer 45

Initial set up costs Limited parameters Edge finish