Session 6

Question 1

What is Base Curve?

Answer 1

The surface curve of a lens that becomes the basis from which the other remaining curves are calculated.

Question 2

where is the BC in the spherical lens

Answer 2

The curve on the front surface is the base curve.

Question 3

what are the curves in a plus spherocylinderical construction lens?

Answer 3

Front surface 2 curves = Base Curve (Weaker) Cross curve (Stronger)
Back surface 1 curve= Spherical Curve (spherical in design)

Question 4

what are the curves in a Minus spherocylinderical construction lens?

Answer 4

Front surface 1 curve= Base curve
Back surface 2 curves = Cross curve (stronger), Toric curve (weaker)

Question 5

Do examples of having the BC and having to find the power in F1 and F2 for Plus and Minus Lenses.

Question 6

What is a Lens Clock?

Answer 6

Pocket sized instrument used for measuring the surface curvature of a lens

Question 7

Practice examples of finding the rx in the oblique meridian

Question 8

Where is 100% of the cylinder power made?

Answer 8

100% off the power is at 90 degrees away from the orginal axis

Question 9

What is the true base power of a lens?

Answer 9

This refers to the true base curve of the front surface of a lens measured with a lens clock.
Can be known as true power and actual power.

Question 10

See table for % = shortcut