Objective 1

Question 1

This allows you to examine the quality of the junctions between the posterior curves on rigid lenses.

Answer 1

overhead light reflection technique

Question 2

The back vertex power of a rigid lens is measured with this instrument.

Answer 2

Lensmeter

Question 3

Usually this has a clock dial face from which the thickness of a contact lens is read.

Answer 3

Thickness gauge

Question 4

This instrument determines the total lens diameter of a rigid contact lens. This instrument has the appearance of a ruler with a V grove in the center.

Answer 4

daimeter gauge

Question 5

This instrument can be used to measure the diameter of a lens along with measuring the width of the peripheral curves and optic zones.

Answer 5

Hand magnifier

Question 6

This instrument will accurately and quickly measure the base curve as well as warpage of a rigid lens.

Answer 6

Radiuscope

Question 7

If a patient has problems with a lens popping out spontaneously on a regular basis the problem is probably due to what type of edge defect?

Answer 7

rolled out edge

Question 8

What allows a fitter to observe the peripheral and intermediate curves and the blend?

Answer 8

fluorescent tube

Question 9

What tool is used on a semi-finished lens to remove approximately two thirds of the plastic from the anterior surface?

Answer 9

70° diamond tool

Question 10

The edge apex of an RGP lens is rounded and polished by using what tool?

Answer 10

hollow sponge tool

Question 11

There are three basic methods of manufacture used for producing rigid contact lenses:

Answer 11

lathe cutting, cast moulding and a combination of those two techniques.

Question 12

Most rigid lenses are manufactured by cutting and polishing the back surface of the lens from a _________.

Answer 12

plastic button

Question 13

While lathe cutting is a very accurate way to manufacture lenses, it is also very expensive because it is _______. New computerized lathes reduce time and costs associated with lathing lenses.

Answer 13

labour intensive

Question 14

______ means that liquid material is poured into a cast to produce lenses. One or more of the lens surfaces may be _____. The cast themselves are expensive, so this generally reduces the choices in lens parameters.

Answer 14

Molding

molded

Question 15

The disadvantages of cast-molded lenses are that they can ____ during the curing process and high quality control is essential.

Answer 15

warp

Question 16

Combination (Lathe & Molding)
With this type of lens, the base curve is achieved by ______ and the power curve is then cut on the front surface with a _____ as required.

Answer 16

molding

lathe

Question 17

The first thing that must be done once rigid contact lenses have been ordered for the patient and received in the office is to _______.

Answer 17

verify the parameters

Question 18

The measurement should be taken with the lens completely ___, as it will not slide if ____. Diameter tolerance should be within + or – ____ millimetres.

Answer 18

dry wet 0.05mm

Question 19

A front surface toric lens will often have a diameter which differs a full millimetre at two different points. This is because of the ____ on the lens. The base down prism point of the lens is much thicker and during manufacture, the thinner sides sometimes loose some diameter. This is referred to as “_______”. This should be recorded as 9.5/9.6.

Answer 19

prism

“off-round”

Question 20

Using a conic choke will allow for the detection of ________.

Answer 20

poor optics

Question 21

Using the over head light technique a smooth ______ will be viewed with the curve across the peripheral curves

Answer 21

J pattern

Question 22

When the star target on a Radiuscope has some lines darker and some lines lighter or blurred, it can indicate ____ or a toric lens design. A warped lens will show toricity on the radiuscope, but will exhibit no toricity on _______. A toric lens will have toric measurements on both the radiuscope and the ______. If toricity is noted on the radiuscope and lensmeter, this would indicate a ____ or ____ lens. If no toricity is noted on the radiuscope, but toricity is noted on the lensmeter, this would indicate a front toric lens.

Answer 22

warpage
lensometry
lensmeter
 back or bitoric
front

Question 23

When using the radiuscope take the lens from the lowest position where a star is visible to the highest position where the star is visible. The distance between the two stars is the measurement of the _____ of the lens.

Answer 23

radius of curvature

Question 24

If the lens measures 7.92, the small hand will be at the 8, but the large hand at 92 makes you realize that it is before the 8 on the scale, not actually at the 8. Think of a clock face that reads 11:57. The small hand will be at the 12, but you automatically know that it is actually 3 minutes before 12:00.

Answer 24

This mistake is the most common error made when using a radiuscope.

Question 25

Different radiuscopes operate slightly differently. Some require turning the coarse adjustment knob ____ from you, while others require turning the knob _____ your body.

Answer 25

away

toward

Question 26

One of the stars seen will be the surface star. The other is called the _____. It is easy to tell the surface star because it is simply a reflection of the surface of the lens so that dirt, water, deposits and scratches are visible.

Answer 26

aerial image

Question 27

To prevent frustration, check the amount of liquid beneath the lens and be sure the plate is ______.

Answer 27

level

Question 28

Using a Keratometer as a Radiuscope

Procedure
Mount the rigid contact lens in the test ball using liquid. The_____ will give a clear image by neutralizing the ball itself as well as cause the lens to stick with the surface tension. Preform Keratometry as usual.
The resulting reading will be the _______ of the base of the rigid lens. If two base curves are read, the base of the lens is a ___ design.

Answer 28

liquid
radius of curvature
toric

Question 29

The ability of the practitioner to recognize and correct subtle abnormalities in __________ can be the deciding factor between the patients’ success and failure with rigid contact lenses.

Answer 29

edge contour

Question 30

By far, the most accurate means of assessing the edge profile has been the ________ technique. Unfortunately, this requires a ________, and the examination technique is extremely difficult to master.

Answer 30

stereomicroscope

stereomicroscope

Question 31

An ________ offers the practitioner an accurate and easy-to-use technique for direct examination of the lens edge. The device utilizes high magnification to view any defects in edge contour.

Answer 31

edge analyzer

Question 32

The _______ of the edge of the contact is that portion of the edge in contact with the upper lid during the blink cycle. The function of the _______ is to taper the lens periphery in order to minimize the interaction between the upper lid and the lens edge.

Answer 32

anterior zone

anterior zone

Question 33

The ______ is a small reverse curve placed onto the posterior lens surface to flare the edge away from the cornea. Its purpose is to allow free movement of the lens across the ______ with eye excursions and permit lens removal by the blinking technique. The _______ also allows the lens to be safely centered onto the cornea when dislocation has occurred.

Answer 33

posterior zone
cornea
posterior zone

Question 34

The lens ____ is the junction between the anterior and posterior zones. This junction must be well rounded to minimize lid awareness during the blink.

Answer 34

apex

Question 35

The “_______”, a well tapered, well rounded edge, which creates minimal lid awareness with the blink.

Answer 35

ideal edge

Question 36

The anterior zone surface is then polished with a 90° ______ tool to a smooth, well-tapered profile.
Placing the lens concave side down on a 105° ________ tool for 30 to 40 seconds incorporates the posterior zone.

Answer 36

velveteen cone

velveteen cone