Decentration, Layout Blocking, Deblocking W4

Question 1

To measure the DBL on a metal or plastic grooved frame made to hold beveled lenses in place

Answer 1

From the deepest part of the groove on one nasal eyewire to the deepest part of the other nasal eyewire at the location where the distance between those lenses is smallest.

Question 2

using a metal or plastic frame, the practitioner makes the correct measurement for MRP height,segment height, and fitting cross height beginning at which

Answer 2

he level of the lowest point on the inside of the eyewire groove up to the level of the pupilheight.

Question 3

Centration is the process of relocating the MRP from the ________________ to the ________________.

Answer 3

boxing center / wearers line of sight

Question 4

The intersection of the main horizontal and vertical lines on the lens protractor and the centration device denotes the location of the

Answer 4

Boxing center of the fame

Question 5

The centration process involves the calculation of exactly where the major reference point of the lenswill be in relationship to the

Answer 5

Boxing center

Question 6

This part of the lens will be used for alignment on the layout grid for SV lenses

Answer 6

Center Lesmeter spot

Question 7

This part of the lens will be used for alignment on the layout grid for Progressive addition lenses

Answer 7

fitting cross

Question 8

This part of the lens will be used for alignment on the layout grid for segmented lenses

Answer 8

Seg center and top

Question 9

Position the dots 0.5mm higher than indicated and at the last step move them all down 0.5mm to the correct position in order to …

Answer 9

make lensmeter dots more visible

Question 10

A + DBL =

Answer 10

DBC

Question 11

When the left lens is convex side up, which way does the lens need to be moved for 2mm of positive decentration

Answer 11

2mm to the left

Question 12

When the right lens is convex side up, which way does the lens need to be moved for 2mm of positive decentration?

Answer 12

2mm to the right

Question 13

A single vision lens calls for +4mm IN decentration in both eyes. Which of the following describes the decentration that will be performed on the right lens?

Answer 13

The center most lensometer spot will be positioned 4mm to the right of the center of the layout grid.

Question 14

When adhesive pad blocking is used with metal lens blocks, a high minus lens is most likely to require…

Answer 14

low-base block (black)

Question 15

Lens with a flatter base curve than a regular spherically-based lens of equal refractive power.

Answer 15

Aspheric Lens

Question 16

Flexible plastic lens blocks used in adhesive pad blocking may be used with … , regardless of base curve.

Answer 16

any powered lens

Question 17

A lens block with an oily film or other foreign material on the surface
An improperly chosen metal base block
An edger that has insufficient coolant flow during edging

Answer 17

Causes of lens slippage

Question 18

Apply an AR designed slip-stop film between the leap pad and the lens surface whenblocking the lens helps with …

Answer 18

AR coated lenses

Question 19

Flexing of the lens causes micro-tears in AR coated lenses. This is referred to as:

Answer 19

Crazing

Question 20

AR coated lenses often have a processing coating that helps with block adhesion during finishing. Thiscoating … be removed (wiped off) until after the lens has been edged.

Answer 20

Should not