Unit 3

Question 1

Which machine measures a patient’s vertex distance?

Answer 1

distometer

Question 2

T/F All lenses gain in minus power when moved away from the eye.

Answer 2

false - they gain in plus power.

Question 3

When moved toward the eye, lenses gain in ______ power.

Answer 3

minus

Question 4

We compensate for vertex distance when the patient’s prescription is +/- _____ diopters.

Answer 4

7

Question 5

To compensate for vertex distance, if the frame was moved closer to the patient’s eye, we would add ____.

Answer 5

plus

Question 6

To compensate for vertex distance, if we move the frame farther from the patient’s face, we would add _____.

Answer 6

minus

Question 7

What is the average vertex distance?

Answer 7

12-14 mm

Question 8

T/F The effective power is what the brain actually sees.

Answer 8

true

Question 9

What is the approximation formula for measuring vertex distance?

Answer 9

DD x mm moved/1000

D=power

Question 10

OD: -13.00 sph
OS: -15.00 sph
moved 5 mm closer to the eye
What should we order from the lab?

Answer 10

OD: -12.12

OS: -13.875