JCAHPO Corrective Lenses 5

Question 1

When fitting a patient's progressive lenses, the segment height should be set so that the fitting cross aligns with:

Accepted Answer

The center of the pupil

Answer

The fitting cross (or pupil center dot) of a progressive lens should align with the center of the pupil to position the distance zone correctly.

Question 2

Which lens coating reduces glare from horizontal surfaces like water and roads by blocking horizontally polarized light?

Accepted Answer

Polarized coating

Answer

Polarized lenses contain a filter that blocks horizontally polarized light, which is the primary component of glare from flat surfaces.

Question 3

A lensometer reading of 2Δ base-down is found in the left lens. To correct for unwanted prism, the optician should:

Accepted Answer

Raise the optical center of the left lens

Answer

Base-down prism is induced when the optical center is below the pupil; raising the optical center eliminates this unwanted prism.

Question 4

Which of the following best describes the purpose of the 'boxing system' in opticianry?

Accepted Answer

A standardized frame measurement system using the smallest enclosing rectangle

Answer

The boxing system defines frame dimensions (A, B, DBL, ED) using the smallest rectangle that encloses each lens opening.

Question 5

A patient's prescription is -6.00 D sphere. Compared to a standard plastic (CR-39) lens, a 1.74 high-index lens would be:

Accepted Answer

Thinner and lighter

Answer

A higher refractive index (1.74 vs. 1.50 for CR-39) allows for a thinner lens and, combined with less material, results in a lighter lens.

(JCAHPO) International Joint Commission Allied Health Personnel in Ophthalmology Practice Test