Decentration, Layout Blocking, Deblocking W4 Flashcards
To measure the DBL on a metal or plastic grooved frame made to hold beveled lenses in place
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.
using a metal or plastic frame, the practitioner makes the correct measurement for MRP height,segment height, and fitting cross height beginning at which
he level of the lowest point on the inside of the eyewire groove up to the level of the pupilheight.
Centration is the process of relocating the MRP from the ________________ to the ________________.
boxing center / wearers line of sight
The intersection of the main horizontal and vertical lines on the lens protractor and the centration device denotes the location of the
Boxing center of the fame
The centration process involves the calculation of exactly where the major reference point of the lenswill be in relationship to the
Boxing center
This part of the lens will be used for alignment on the layout grid for SV lenses
Center Lesmeter spot
This part of the lens will be used for alignment on the layout grid for Progressive addition lenses
fitting cross
This part of the lens will be used for alignment on the layout grid for segmented lenses
Seg center and top
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 …
make lensmeter dots more visible
A + DBL =
DBC
When the left lens is convex side up, which way does the lens need to be moved for 2mm of positive decentration
2mm to the left
When the right lens is convex side up, which way does the lens need to be moved for 2mm of positive decentration?
2mm to the right
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?
The center most lensometer spot will be positioned 4mm to the right of the center of the layout grid.
When adhesive pad blocking is used with metal lens blocks, a high minus lens is most likely to require…
low-base block (black)
Lens with a flatter base curve than a regular spherically-based lens of equal refractive power.
Aspheric Lens
Flexible plastic lens blocks used in adhesive pad blocking may be used with … , regardless of base curve.
any powered lens
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
Causes of lens slippage
Apply an AR designed slip-stop film between the leap pad and the lens surface whenblocking the lens helps with …
AR coated lenses
Flexing of the lens causes micro-tears in AR coated lenses. This is referred to as:
Crazing
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.
Should not
