CPOA Contact Lens Basics 2

Question 1

Which contact lens parameter describes the curvature of the back surface of the lens?

Accepted Answer

Base curve

Answer

Base curve (BC) describes the curvature of the posterior lens surface and determines how the lens fits on the cornea.

Question 2

A patient's contact lens prescription reads: -2.50 -1.25 x 180. This lens is best described as:

Accepted Answer

Toric soft lens

Answer

The presence of a cylinder power (-1.25) and axis (180) indicates a toric lens designed to correct astigmatism.

Question 3

What is the primary advantage of daily disposable contact lenses over monthly replacement lenses?

Accepted Answer

Eliminated need for lens care solutions

Answer

Daily disposable lenses are discarded after each use, eliminating the need for cleaning and storage solutions.

Question 4

Which material property of contact lenses is described by the term 'Dk/t'?

Accepted Answer

Oxygen transmissibility

Answer

Dk/t represents oxygen transmissibility, where Dk is oxygen permeability and t is lens center thickness.

Question 5

A patient reports their soft contact lenses feel dry by the end of the day. Which lens property most directly affects this complaint?

Accepted Answer

Water content

Answer

Higher water content lenses can evaporate moisture more readily, contributing to end-of-day dryness symptoms.

(CPOA) Certified Paraoptometric Assistant Practice Test