Soft Contact Lens Properties and Parameters Quiz

Question 1

What are repeating units of high molecular weight chains called?

Answer 1

Polymers

Question 2

What are the two major groups of soft contact lenses material?

Answer 2

Hydrogel, Silicone Hydrogel

Question 3

What was a major concern in the early designs of hydrogel contact lenses?
Lack of oxygen transmission to cornea

Answer 3

Hypoxia

Question 4

What is a solution used to increase oxygen transmission in hydrogel lenses to the water content of the lens?

Answer 4

Increase

Question 5

Will creating a thinner contact lens increase oxygen transmission in hydrogel lenses?

Answer 5

Yes

Question 6

What are advantages of high water content hydrogel contact lenses?

Answer 6

Quick adaptation
Better comfort
Easier to handle because they are thicker

Question 7

What are disadvantages of high water content hydrogel contact lenses?

Answer 7

Fragile and prone to tearing
Deposits
Dehydration

Question 8

What does the acronym USAN mean?

Answer 8

United States adopted name

Question 9

What are examples of USAN nomenclature?

Answer 9

Polymacon
Nefilcon A
Omafilcon B

Question 10

What is the biggest challenge during the development of silicone hydrogel lenses?

Answer 10

Silicone is hydrophobic and does not combine well with hydrophilic hydrogel materials

Question 11

As water content increases in hydrogel contact lenses, the oxygen permeability?

Answer 11

Increases

Question 12

As water content increases in silicone hydrogel contact lenses, the oxygen permeability?

Answer 12

Decreases

Question 13

What is referred to as the Dk of material?
Depends upon oxygen solubility and diffusivity of the material
Units in Fatt or Barrer

Answer 13

Oxygen permeability

Question 14

What is the term for measuring how quickly oxygen moves through the material?

Answer 14

Diffusivity

Question 15

What is the term for measuring how much oxygen the material can hold?

Answer 15

Solubility

Question 16

What is referred to as the Dk/t
Units in Barred. cm
Impacted by oxygen solubility and diffusivity of the matieral

Answer 16

Oxygen transmissibilty

Question 17

What is the stiffness of the contact lens material referred to as?

Answer 17

Modulus

Question 18

If brand A has a modulus of 1.1, and brand B has a modulus of 0.40. Which brand is most likely to feel more comfortable with the patient?

Answer 18

Brand B,

lower modulus = less stiff

Question 19

What are different ways to improve the wettability of a soft contact lens?

Answer 19

• Increase the amount of water in hydrogel lens
• Add wetting agents to blister pack
• Coat the surface of silicone hydrogels with a hydrophilic material
• Add plasma treatments to silicone hydrogels to make them more hydrophilic

Question 20

What does surface friction of contact lens impacts?

Answer 20

Comfort

Question 21

If brand A has a coefficient of friction of 0.423 and brand B has a coefficient of 0.0018, which brand is most likely to feel more comfortable for the patient?

Answer 21

Brand B

Lower coefficient = less force on cl during blinking

Question 22

What is the instrument used to measure the percentage of transmission of different wavelengths called?

Answer 22

Spectrophotometer

Question 23

What are the five factors that describe the geometric components of a soft contact lenses?

Answer 23

Diameter
Sagittal Depth 
Thickness
Radius of Curvature 
Edge Appearance