NOCE Optical Instrumentation Usage 4

Question 1

When using a Burton lamp (UV lamp) to inspect contact lenses with fluorescein, a dark (black) area under a rigid contact lens indicates:

Accepted Answer

Bearing or touch between the lens and cornea

Answer

A dark area under a rigid lens during fluorescein evaluation indicates lens-to-cornea touch or bearing, where fluorescein is displaced by contact pressure.

Question 2

A pachymeter instrument is used to measure:

Accepted Answer

Corneal thickness

Answer

A pachymeter measures corneal thickness, which is important for contact lens fitting and monitoring corneal health.

Question 3

When using a Geneva lens measure on a minus lens, the gauge pointer deflects:

Accepted Answer

In the negative direction

Answer

A minus (concave) lens surface causes the center pin of the Geneva lens measure to be pushed back, resulting in a negative (minus) reading.

Question 4

A prismatic effect found at the optical center of a lens during lensometry most likely indicates:

Accepted Answer

A manufacturing defect or incorrect prism in the prescription

Answer

Prism measured at the optical center of the lens indicates either intentional prescribed prism or a manufacturing error, since a properly made non-prism lens should have zero prism at its optical center.

Question 5

The slit lamp biomicroscope is used in optical practice primarily to:

Accepted Answer

Examine the fit and position of contact lenses on the eye

Answer

The slit lamp allows the optician or practitioner to examine contact lens centration, movement, edge lift, and fit characteristics under high magnification.

NOCE - National Opticianry Competency Examination Practice Test

NOCE - National Opticianry Competency Examination Practice Test

NOCE Optical Instrumentation Usage 4