ABO NOCE Basic Opticianry General Practice 5

Question 1

A lensometer power cross shows +2.00 at 180 and +4.00 at 090. The prescription in minus-cylinder form is:

Accepted Answer

+4.00 -2.00 x 090

Answer

In minus-cylinder form, the sphere equals the highest plus meridian (+4.00 at 090); cylinder = +2.00 − +4.00 = −2.00; axis = 090.

Question 2

Pantoscopic tilt is the angle formed between the lens plane and:

Accepted Answer

The vertical plane

Answer

Pantoscopic tilt is measured from the vertical plane; standard tilt is 8–12° with the bottom of the lens closer to the face.

Question 3

A patient complains of a 'swim' or 'sway' effect with new progressive lenses. The most likely cause is:

Accepted Answer

Peripheral distortion inherent in the progressive corridor design

Answer

Progressive lenses have unavoidable peripheral astigmatic distortion outside the central corridor, causing a swim sensation during adaptation.

Question 4

According to ANSI Z80.1, the allowable axis tolerance for a 2.00 D cylinder power is:

Accepted Answer

± 7°

Answer

ANSI Z80.1 specifies ±7° axis tolerance for cylinder powers between 1.25 D and 2.00 D.

Question 5

A patient inadvertently receives lenses with base-in prism. This will most likely cause the patient to experience:

Accepted Answer

Eyestrain or diplopia as the eyes are forced to diverge more than normal

Answer

Base-in prism displaces images temporally (toward the apex), requiring the eyes to diverge; excess divergence demand causes eyestrain or diplopia.

ABO NOCE Basic Opticianry Practice Test