ABO ABO Industry Standards 5

Question 1

Prentice's rule states that induced prism equals:

Accepted Answer

Power (D) × decentration (cm)

Answer

Prentice's rule: Prism (Δ) = Power (diopters) × decentration (centimeters), used to calculate induced prism from lens decentration.

Question 2

What is the base curve of an ophthalmic lens?

Accepted Answer

The curve specifically designated as the reference or 'base' from which other curves are measured

Answer

The base curve is the reference surface curve (usually the front curve) from which the lens prescription is built and other curves are calculated.

Question 3

Under ANSI Z80.3, sunlens luminous transmittance categories range from Category 0 to Category 4. What does Category 4 indicate?

Accepted Answer

Very dark lenses (3-8% transmittance) not suitable for driving

Answer

Category 4 sunlenses have very dark tints with only 3-8% luminous transmittance and are not recommended for use while driving.

Question 4

In frame standards, the 'boxing system' is used to:

Accepted Answer

Provide a standardized method for measuring lens and frame dimensions

Answer

The boxing system is a standardized method using a rectangle (box) around the lens aperture to measure frame and lens dimensions such as A, B, DBL, and ED.

Question 5

What is the 'effective diameter' (ED) of a lens in the boxing system?

Accepted Answer

The diameter of the smallest circle that will encompass the entire lens shape

Answer

The effective diameter (ED) is the diameter of the smallest circle centered on the boxing center that completely encloses the lens shape.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO ABO Industry Standards 5