NOCE Dispensing and Fitting Procedures 5

Question 1

What is the recommended minimum fitting height for most progressive addition lenses?

Accepted Answer

18 mm

Answer

Most standard progressive lenses require a minimum fitting height of 18 mm to accommodate the full corridor length and reading zone.

Question 2

A dispensing optician measures a patient's distance PD as 66 mm and near PD as 62 mm. The difference indicates:

Accepted Answer

Normal convergence of approximately 2 mm per eye at near

Answer

Eyes converge when viewing near objects, so near PD is typically 4–6 mm less than distance PD, representing approximately 2 mm per eye.

Question 3

When using a frame heater (hot air or salt pan) to adjust a plastic frame, the frame should be:

Accepted Answer

Heated evenly until pliable, then adjusted and held until cooled

Answer

The frame should be heated evenly until the plastic becomes pliable, then adjusted and held in the new position until it cools to retain the shape.

Question 4

Which verification step checks that prism has not been unintentionally introduced into a finished lens?

Accepted Answer

Locating the optical center with a lensometer and comparing to the expected position

Answer

Locating the optical center with the lensometer confirms it is positioned where specified; a displaced OC introduces unwanted prism.

Question 5

A patient's new glasses cause a 'floor tilt' perception when walking. This is MOST commonly associated with:

Accepted Answer

Adaptive difficulty with a progressive lens corridor

Answer

The 'swimming' or floor-tilt perception is a classic adaptation symptom for new progressive lens wearers as the brain adjusts to peripheral distortion zones.

NOCE - National Opticianry Competency Examination Practice Test

NOCE - National Opticianry Competency Examination Practice Test

NOCE Dispensing and Fitting Procedures 5