Chapter 9

Question 1

In the making of concentric style bifocals, the different power zones (distance and near) may be ground on:
a) the front surface b) the back surface
c) either surface d) both surfaces

Answer 1

either surfaces

Question 2

The addition of fluorine to the rigid lens ingredients increases:

Answer 2

wettability

Question 3

Which of the following instruments would NOT be used to verify the lens diameter in the office?
a) diameter gauge b) radiuscope
c) measuring magnifier d) projection magnifier

Answer 3

Radiuscope

Question 4

Mounting the lens blank in the lathe so that the face of the button is perpendicular to the spindle is necessary to avoid:

Answer 4

unwanted prism

Question 5

When reading the radius of curvature of the back surface with the radiuscope, the lens is floated on a drop of liquid to:
a) neutralize the reflection from the front surface
b) keep the front surface clean
c) level the lens
d) none of the above

Answer 5

a) neutralize the reflection from the front surface

Question 6

During the lathing process for toric lenses, cylinder power is generated by:

Answer 6

Squeezing the lens in a crimping tool

Question 7

When the lens power is verified, placing the concave surface against the lensometer aperture will reveal ______ power.

Answer 7

Back vertex

Question 8

Which of the following polishes should NOT be used to polish gas permeable lenses?
a) Silvo b) Sil-02-Care c) Alox d) X-Pal

Answer 8

a) Silvo

Question 9

After reducing the overall diameter, which of the following additional modifications are required?
a) applying peripheral curves b) blending
c) edge shaping and polishing d) all of the above

Answer 9

d) all of the above

Question 10

Removal of plastic from the bottom of a lens to produce a flat edge that will control rotation is called: a) prism ballast b) truncation
c) base curve d) blending

Answer 10

b) truncation

Question 11

In-office power changes should be limited to ± __ D. or less.
a) 0.25 b) 0.50 c) 1.00 d) 2.00

Answer 11

b) 0.50

Question 12

When rigid lenses are manufactured, which parameter is cut first?
a) anterior convex curve
b) central posterior curve
c) CN bevel
d) posterior peripheral curve

Answer 12

b) central posterior curve

Question 13

After the sharp junctures between curves on the lens posterior are smoothed out, they are called:
a) blends c) lenticulation b) bevels d) apex

Answer 13

a) blends

Question 14

Which in-office modification is the easiest to perform?
a) changing base curve
b) adding plus power
c) truncation
d) adding minus power

Answer 14

d) adding minus power

Question 15

Calculation of which lens parameter is NOT under the control of the fitter?
a) central posterior curve
b) posterior optical zone
c) anterior power curve
d) center thickness

Answer 15

a) centeral posterior curve

Question 16

Polishing the surfaces of rigid gas permeable lenses should be performed:
a) every six months
b) only when it is needed
c) every year
d) never

Answer 16

b) only when it is needed

Question 17

Lens blends and “ski edge” can be verified using a:
a) keratometer
b) junctometer
c) radiuscope
d) long fluorescent light bulb

Answer 17

d) long fluorescent light bulb

Question 18

An in-office modification that can be done to thin the edge of a minus lens is the:
a) hyperflange b) myoflange
c) CN bevel d) ski edge

Answer 18

c) CN bevel

Question 19

The ideal finished edge thickness for rigid lenses, regardless of whether they are plus or minus, is____mm a) 0.08-0.12 b) 0.04-0.10 c) 0.20-0.44 d) 0.5-1.0

Answer 19

a) 0.08-0.12

Question 20

In aspheric lens design, the change in curvature that occurs from the center to the edge of the aspheric zone is called:

Answer 20

eccentricity

Question 21

Hydrogel lens materials allow the transport of oxygen to the cornea and carbon dioxide away from the cornea because they contain:

Answer 21

three dimensional polymers

Question 22

The FDA has created four lens groups to clarify categories of similar hydrophilic lens polymers. These groups are defined by:

Answer 22

water content and electrostatic properties

Question 23

During the lathe cutting process, humidity must be controlled at a low level in order to:
a) avoid premature hydration
b) maintain quality standards
c) avoid destruction of the lens
d) all of the above

Answer 23

d) all of the above

Question 24

A spin cast lens will generate:

Answer 24

an aspheric back surface

Question 25

The lens stabilization system most often used to prevent or control rotation of toric soft lenses is:

Answer 25

Prism ballast

Question 26

The term GMP is the acronym for:

Answer 26

Good manufacturing practices

Question 27

Buttons and raw materials used in hydrogel lens manufacturing are tested and quarantined:
a) to ensure that they comply with approved standards
b) to ensure that they meet approved specifications
c) before they can be used in production
d) all of the above

Answer 27

d) all of the above

Question 28

Which of the following parameters of hydrogel lenses can be readily verified in the office?
a) base curve b) power c) diameter d) both b and c

Answer 28

d) both b and c

Question 29

Which of the following hydrogel lens parameters may be modified in the practitioner’s office?
a) base curve b) power
c) diameter d) none of the above

Answer 29

d) none of the above