Multifocals
Specific type of PD measurement that is taken for segmented multifocals
Binocular PDs
Formula used to calculate segment drop
seg height - B/2
Specific type of PD measurement that is taken for PALs
Minocular
Where is the add power located on a progressive lens?
Located temporally
After checking the screws, where do you begin standard bench alignment on a frame?
At the bridge
What is the add power of a bifocal lens that reads -3.00 in the distance and -0.50 in the segment?
+2.50
Formula used to calculate segment inset
(DPD - NPD)/2
The name of the point under the fitting cross
Prism reference point
Where to read/verify the add power of the lens
Near reference point
When the frame is twisted about the bridge
X-ing
Calculate horizontal decentration using FPD: 68mm PPD: 70mm
1 out each eye
Formula used to calculate horizontal decentration
(A+DBL - DPD)/2
Which vertex power is used to verify the distance prescription?
Back vertex power
Tolerance for progressive add power under 4.00D
+/- 0.12D
This material is commonly used in drill mounts but can stretch over time
Polycarbonate
Another name for a Franklin-style bifocal
Executive
Formula used to calculate Total Inset
(A+DBL - Near PD)/2
The process of purposefully inducing equal amounts of base down prism into progressive lenses during the surfacing process
Prism thinning
Formula used for horizontal decentration
(A + DBL)/2 - Mono PD
True or false? Drilling straight through poly all at once can result in an unstable mounting.
True
Blended bifocals are another form of _____
Round segment bifocal
R: -7.00 sph, L: -5.00 sph
Add: +1.50, Height: 18/16
Is this acceptable?
No, both lenses are greater than 3.375D and the heights are more than 1mm apart
This PAL centration method uses the distance from the PRP to the fitting cross instead of the fitting cross itself
Hidden circles
Segment height is measured from ____ to _____
A multifocal lens with a flat-top bifocal-style segment in the lower portion of the lens and an inverted flat-top bifocal-style segment in the upper portion of the lens
Double-D lens?