ABO NOCE Basic Opticianry Ophthalmic Optics Questions and Answers 2

Question 1

A lens with a power of +2.00 D has a focal length of:

Accepted Answer

50 cm

Answer

Focal length (in meters) equals 1 divided by power in diopters; 1/2.00 = 0.50 m = 50 cm.

Question 2

Chromatic aberration in ophthalmic lenses is caused by:

Accepted Answer

Dispersion of light into its spectral components by the lens material

Answer

Different wavelengths of light refract at slightly different angles through a lens, causing chromatic aberration due to material dispersion.

Question 3

The Abbe value (V-number) of a lens material is used to measure its:

Accepted Answer

Resistance to chromatic aberration

Answer

A higher Abbe value indicates less chromatic aberration; it measures how well a material keeps colors together.

Question 4

Which type of lens surface eliminates the tangential and sagittal focus errors simultaneously?

Accepted Answer

Atoric

Answer

Atoric surfaces are designed to correct both tangential and sagittal oblique astigmatic errors simultaneously.

Question 5

The refractive index of standard CR-39 plastic lens material is approximately:

Accepted Answer

1.50

Answer

CR-39 (allyl diglycol carbonate) has a refractive index of approximately 1.499, commonly cited as 1.50.

ABO NOCE Basic Opticianry Practice Test