ABO NOCE Basic Opticianry Ophthalmic Optics 4

Question 1

A patient's prescription is OD -4.00 -1.50 x 090. What is the power in the 180 meridian?

Accepted Answer

-5.50 D

Answer

In a minus-cylinder prescription, the sphere power acts along the axis meridian (090), and the full cylinder power is added 90° away (180°): -4.00 + (-1.50) = -5.50 D.

Question 2

Which surface of a meniscus lens is typically convex?

Accepted Answer

The front (object-side) surface

Answer

In a standard ophthalmic meniscus lens, the front (convex) surface curves toward the world and the back (concave) surface curves toward the eye.

Question 3

What does 'base curve' refer to in ophthalmic lens terminology?

Accepted Answer

The reference surface curvature, usually the front convex surface

Answer

The base curve is the reference surface power of an ophthalmic lens, most commonly expressed as the front (convex) surface power in diopters.

Question 4

A cylinder lens with axis at 45° corrects astigmatism in which meridian?

Accepted Answer

The 135° meridian

Answer

A cylinder lens with axis at 45° has no power along the 45° meridian (the axis) and full correcting power in the 135° meridian (perpendicular to the axis).

Question 5

The spherical equivalent of -3.00 -2.00 x 090 is:

Accepted Answer

-4.00 D

Answer

Spherical equivalent = sphere + (cylinder/2) = -3.00 + (-2.00/2) = -3.00 + (-1.00) = -4.00 D.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Ophthalmic Optics 4