Unit 6: Progressive Addition Lenses (PAL)

Question 1

Varilux 2, designed in 1973, used ________ lenses instead of regular spherical ones.

Answer 1

aspherical

Question 2

Which company had the first patent on progressive lenses in 1959?

Answer 2

Essilor with the Varilux PAL

Question 3

A soft/hard progressive lens design has a rapid power change in a small area.

Answer 3

hard

Question 4

A soft/hard progressive lens design has a gradual power change over a large area.

Answer 4

soft

Question 5

T/F PALs are designed with aspheric surfaces.

Answer 5

true

Question 6

T/F Conventional PALs have 4 zones: distance, intermediate, near, and periphery.

Answer 6

true

Question 7

T/F Hard PAL designs have a gradual power change over a large area of the lens.

Answer 7

false

Question 8

T/F The higher the add power, the harder the PAL design will be.

Answer 8

true

Question 9

A mono design means the PAL has the same design for all add powers.

Answer 9

true

Question 10

A symmetrical PAL design means there is no difference in design between the left and right lens.

Answer 10

true

Question 11

It does not matter if we pre-adjust the frame front prior to taking fitting measurements with a PAL - the lab will take care of it.

Answer 11

false

Question 12

If a patient must lower her head to see clearly in the distance, the progressive lenses are positioned too low.

Answer 12

false

Question 13

We leave the markings on the lens during dispensing to be sure the fitting cross is centered over the patient’s pupil.

Answer 13

true

Question 14

To alleviate the effects of distortion, peripheral blur, we should: increase vertex distance, increase pantoscopic tilt, and increase parabolic curve (face form).

Answer 14

false

Question 15

The distance between all laser markings on PALs is:
A. 17 mm
B. 23 mm
C. 32 mm
D. 34 mm
E. none of the above

Answer 15

D. 34 mm

Question 16

The dot below the fitting cross is known as:
A. the major reference point
B. the optical center
C. the prism reference point
D. the mechanical center
E. the drop

Answer 16

C. the prism reference point

Question 17

Which of the following is a contraindication of a good candidate for PALs:
A. is a first-time wearer
B. is an early presbyope
C. has high cylinder in their Rx
D. has motion sickness or balance problems

Answer 17

D. has motion sickness or balance problems

Question 18

We should always use binocular PDs for PALs. T/F

Answer 18

false

Question 19

Prism thinning (also called equi-thinning), applies base down prism to help make the finished PAL lenses thinner.

Answer 19

true