Contact Lens Basics Flashcards

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

Answer: Base curve

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

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

Answer: Toric soft lens

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

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

Answer: Eliminated need for lens care solutions

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

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

Answer: Oxygen transmissibility

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

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

Answer: Water content

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

Extended wear contact lenses are FDA-approved for continuous wear up to how many days?

Answer: 30 days

FDA-approved silicone hydrogel extended wear lenses can be worn continuously for up to 30 days and nights.

Which type of contact lens solution combines cleaning, rinsing, disinfecting, and storing in one product?

Answer: Multipurpose solution

Multipurpose solutions (MPS) perform multiple lens care functions in a single convenient product.