NOCE Optical Instrumentation Use 3

Question 1

A pachymeter is used in optometry and ophthalmology to measure which ocular structure?

Accepted Answer

Corneal thickness

Answer

A pachymeter measures corneal thickness, which is important for conditions like glaucoma screening and pre-refractive surgery evaluation.

Question 2

On a manual lensometer, what is the purpose of rotating the eyepiece reticle before beginning a measurement?

Accepted Answer

To focus the reticle for the examiner's own eye

Answer

Rotating the eyepiece adjusts the reticle to be sharply focused for the individual examiner's eye, correcting for their own ametropia.

Question 3

When measuring a progressive addition lens (PAL) with a lensometer, where on the lens should you place the distance reference mark?

Accepted Answer

At the prism reference point (PRP) or fitting cross

Answer

The prism reference point (PRP) or fitting cross is the standard location for placing a PAL in the lensometer to read distance power.

Question 4

A contact lens thickness gauge (dial gauge) measures which parameter in hundredths of a millimeter?

Accepted Answer

Center or edge thickness

Answer

A contact lens thickness gauge measures center or edge thickness in increments typically of 0.01 mm.

Question 5

When using an auto-refractor, the instrument measures which of the following to determine the refractive error?

Accepted Answer

The reflection of an infrared target from the retina

Answer

Auto-refractors project an infrared target onto the retina and analyze the reflected wavefront to objectively calculate refractive error.

NOCE - National Opticianry Competency Examination Practice Test