Test Reviews Part 2

Question 1

Which of the following material components has the highest gas permeability?
a) Fluorine
b) PMMA
c) Butyrate
d) Silicone

Answer 1

d) Silicone

Question 2

Application of fluorescein should be used when

Answer 2

Evaluating a rigid gas permeable lens fit

Question 3

If the diagnostic rigid gas permeable lens placed on the eye results in minimal movement, which of the following
will increase the movement on the lens ordered for the patient?

Answer 3

Decreasing overall lens diameter

Question 4

These will all decrease the movement of the rigid gas permeable lens

Answer 4

Increasing overall diameter
Increasing optic zone diameter
Increasing sagittal depth

Question 5

If a soft contact lens decenters laterally, exposing a portion of the patient’s limbus, what change in parameter
would improve this situation?

Answer 5

Increasing lens diameter

Question 6

When evaluating a diagnostic soft lens on a patient, you notice that movement is sluggish after only a few
minutes. Which of the following changes would you make to the lenses that are ordered for the patient?

Answer 6

Flatten base curve

the fit will be loosened and movement will be
increased.

Question 7

Increasing the overall lens diameter and steepening the base curve will … the lens and … its movement

Answer 7

tighten
decrease

Question 8

Which edge design is recommended for a + 15.00 D aphakic RGP lens?

Answer 8

Lenticular myoflange

This minus carrier design increases edge thickness and enables a low-riding high-plus lens to center better.

Question 9

Which of the following lens designs would provide the best visual result for this patient?
K’s 42.00 @ 180 / 42.50 @ 90
Rx -3.50 -1.75 x 180
a) Spherical rigid gas permeable lens
b) Spherical soft lens
c) Soft toric lens
d) Back surface toric rigid gas permeable lens

Answer 9

c) Soft toric lens

Since the astigmatism is lenticular and is not found on the cornea, a spherical rigid gas permeable lens will not mask
the astigmatism since it is lenticular. There is not enough corneal astigmatism to stabilize a back surface toric lens

Question 10

To aid in the positioning of a rigid prism ballast lens riding too low and slipping underneath the lower lid, which
of the following might be helpful?
a) Hyperflange
b) More prism
c) Truncation
d) Thinner edge design

Answer 10

c) truncation

Truncating the lower edge of the lens would help to provide a flatter, thicker surface to interact with the lower lid,
enabling the lens to rest in the proper position.

Question 11

The following rigid gas permeable diagnostic lens is placed on a patient’s eye: -2.00 9.2
An over-refraction is performed with the following results: plano +1.50 x 95
Which of the following lens parameters would you order for the patient?
a) 43.50 -0.50 -1.50 x 5 9.2
b) 43.50 -2.00 -1.50 x 5 9.2
c) 43.50 plano -1.50 x 95 9.2
d) 43.50 plano + 1.50 x 5 9.2

Answer 11

a) 43.50 -0.50 -1.50 x 5 9.2

When applying the sphero-cylindrical over-refraction to a spherical rigid gas permeable lens, first put the overrefraction
into minus cylinder form. Plano +1.50 x 95 becomes +1.50 -1.50 x 5. Add the spherical component to the
existing spherical component (-2.00 plus +1.50 becomes -0.50). Then simply tag on the cylindrical portion of the
over-refraction.

Question 12

The following soft lens is placed on a patient’s eye: 8.8 -4.00 14.0 . An over-refraction is performed resulting
in -0.75 D sphere. Which of the following lens parameters would you order for the patient?
a) 8.8 -3.25 14.0
b) 8.8 -4.00 14.0
c) 8.8 -4.75 14.0
d) 8.8 -5.25 14.0

Answer 12

c) 8.8 -4.75 14.0

Question 13

In an RGP lens, a poorly finished transitional zone between the optic zone and the lens edge can be evaluated by:
a) Radiuscope
b) Lensometer
c) Profile analyzer
d) Contacto gauge

Answer 13

c) Profile analyzer

Question 14

A soft toric lens, spherical and aspheric rigid gas permeable lens will all correct …

Answer 14

Astigmatism

Question 15

An excellent material for a patient with keratoconus would be:

Answer 15

Fluoro Silicone Acrylate

rigid lens material

Question 16

Polymacon
Crofilcon A
Bufilcon A

Answer 16

Soft lens materials, flexible

Question 17

A prism ballast RGP lens requires how much prism for proper orientation?

Answer 17

0.75 to 1.50 D

Question 18

Which of the following could be considered in the fitting of a keratoconus patient?
1) Aspheric
2) McGuire
3) Soper
4) Tangent Streak

Answer 18

1) Aspheric
2) McGuire
3) Soper

Question 19

Tangent Streak
lenses are used in the treatment of

Answer 19

presbyopia

Question 20

The following soft lens is placed on a patient’s eye: 8.4 -2.00 14.2
An over-refraction is performed with the following results: -1.00 –0.50 x 174
Which of the following lens parameters would you order for the patient?

a. -2.00 14.2
b. -2.75 14.2
c. -3.25 14.2
d. -3.75 14.2

Answer 20

c. -3.25 14.2

When applying the results of an over-refraction to a SOFT lens, transpose the over-refraction to minus cylinder. Then
determine the spherical equivalent (-1.25 D in this case) and add this to the existing power.

Question 21

Given the following information: K’s 45.00 @ 180 / 44.00 @ 90
Rx –3.00 +1.00 x 180 Upper lid positioned at the superior limbus. Which of the following set of lens
specifications would best simulate an intrapalpebral rigid lens fitting?
a) 43.50 –1.50 8.5
b) 43.50 –1.50 9.5
c) 44.50 –2.00 8.5
d) 44.50 –2.50 8.5

Answer 21

d) 44.50 –2.50 8.5

Intrapalpebral lenses are designed to center between the upper and lower eye lids. To achieve this positioning, an on
K or steeper than K base curve is designed with diameters of 9.0 mm or smaller.

Question 22

Given the following information, which of the following set of lens specifications would best simulate a lid
attachment rigid lens fitting?
K’s 42.00 @ 180 / 43.00 @ 90
Rx –2.00 –0.87 x 180 Upper lid positioned 2 mm below the superior limbus
a) 41.50 –1.50 9.5
b) 42.50 –2.50, 8.5
c) 43.00 –2.50 9.5
d) 43.00 –3.00 8.2

Answer 22

a) 41.50 –1.50 9.5

“Lid attachment” lenses are designed to fit with the upper edge of the lens positioned under the upper eye lid. To
achieve this positioning, a flatter than K, larger diameter (over 9.0 mm) is generally used

Question 23

Which of the following bifocal designs represents a translating design?
a) Diffraction design
b) Crescent design
c) Reverse centrad design
d) Concentric design

Answer 23

B) cresent design

Question 24

Given the following information, which of the listed rigid lens designs would you order to best correct this
wearer’s vision?
K’s 42.00 @ 180 / 45.00 @ 90
Rx -3.00 -2.25 x 180

Answer 24

42.00 / 45.00 -3.00 -2.25 (Rx form)

The base curves will parallel the K readings and the power in the lens will properly correct the astigmatism. A
spherical lens design will rock on the 180 degree meridian causing discomfort and the chance of lens displacement or
expulsion.

Question 25

The performance of a soft toric lens depends on:

Answer 25

1) Corneal topography
2) Lid shape
3) Lid positioning
4) Lid tightness

Question 26

Given the following information, which of the following RGP lens designs will best correct this wearer’s vision?
K’s 42.50 @ 180 / 42.50 @ 90
Rx -3.00 - 1.00 x 90
a) Bitoric design
b) Anterior toric design
c) Spherical design
d) Soper Cone design

Answer 26

b) anterior toric

The base curve will parallel the spherical cornea and the prism ballast will position the cylinder in the lens on the axis
of the Rx

Question 27

A Soper cone lens design is used for …

Answer 27

Keratoconus

Question 28

A … should always be recorded with the flat meridian first and the steep meridian second.

Answer 28

toric rigid lens

Question 29

What is necessary to consider when fitting RGP aphakic contact lenses?

Answer 29

Vertex distance
Minus-carrier lenticular designs
Proper lens centration

Question 30

An aphakic patient with K readings of 40.50 @ 180 / 41.25 @ 90, large palpebral fissures and flaccid lower lids
is a good candidate for:

Answer 30

Myoflange lenticular

A lenticular (myoflange) lens is best suited for aphakic patients with corneal curvatures
flatter than 45.00 D, large palpebral fissures and flaccid lower lids.

Question 31

The patient has a horizontal visible iris diameter (HVID) of 12.5 mm. The best choice for initial soft lens
diameter would be:

Answer 31

14.5

The general rule of thumb for determining initial soft lens diameter is to choose a lens 2.0 mm larger than the cornea.
This will result in 1.0 mm on either side of the cornea and will aid lens centration

Question 32

A single cut aphakic lens is best suited for patients with ________ apertures and _______ corneas:

Answer 32

Small / steep

Question 33

The general rule of thumb for determining initial soft lens diameter is to choose a lens … mm larger than the cornea.

Answer 33

2.0 mm

Question 34

Where is the power curve on a spin-cast soft lens?

Answer 34

The back surface

Question 35

Keratoconus and penetrating keratoplasty fittings are best accomplished by which of the following methods?
a) Nomogram
b) K’s and Rx
c) Diagnostic fitting
d) Molded impression

Answer 35

c) Diagnostic fitting

Question 36

The following ametropia frequently results in high riding rigid lenses:

Answer 36

High myopia

Question 37

A good example of a bifocal contact lens that may rotate without vision impairment is:

Answer 37

Aspheric

Question 38

A toric soft lens will correct:
a) Residual astigmatism
b) Moderate astigmatism (greater than 2.00 D)
c) Low astigmatism (0.75 to 2.00 D)
d) All of the above

Answer 38

d) All of the above

Question 39

A lens fitted for keratoconus should:
a) Flatten the apex
b) Ride high
c) Align the apex
d) Ride low

Answer 39

c) Align the apex

Question 40

Which of the following is a translating bifocal lens design?
a) Concentric
b) Aspheric
c) Diffractive
d) Segmented

Answer 40

d) segmented

A translating lens (Le. segmented) must move upwards for near
vision. When properly fitted, this lens design will project “alternating” images on the retina-one for distance, one for
near.