Contact Lens Fitting & Patient Care Flashcards
7 cards from real CPOT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Contact Lens Fitting & Patient Care flashcards as text
Which contact lens material has the highest oxygen transmissibility (Dk/t)?
Answer: Silicone hydrogel
Silicone hydrogel lenses allow significantly more oxygen to reach the cornea than conventional hydrogel or PMMA lenses because the silicone component is highly oxygen-permeable.
Which contact lens design is used to correct astigmatism?
Answer: Toric lens
Toric lenses have different powers in different meridians and include stabilization features to correct astigmatism by staying properly oriented on the eye.
What does the measurement 'Dk/t' represent in contact lens specifications?
Answer: Oxygen transmissibility
Dk/t represents oxygen transmissibility, where Dk is the material's oxygen permeability and t is the lens center thickness; higher values mean more oxygen reaches the cornea.
Which contact lens replacement schedule carries the lowest risk of deposit buildup?
Answer: Daily disposable
Daily disposable lenses are discarded after each use, eliminating the accumulation of protein, lipid, and calcium deposits that build up on reusable lenses over time.
What is the base curve of a contact lens?
Answer: The central posterior radius of curvature
The base curve is the radius of the central posterior (back) surface of the contact lens; it must closely match the corneal curvature to achieve an appropriate fit.
Rigid gas-permeable (RGP) contact lenses are considered the primary contact lens option for which condition?
Answer: Keratoconus with irregular corneal shape
RGP lenses are preferred for keratoconus because their rigid anterior surface creates a smooth optical interface over the irregular cornea, providing superior visual acuity.
What is the primary clinical advantage of rigid gas-permeable (RGP) lenses over soft contact lenses?
Answer: Superior oxygen transmissibility and optical clarity
RGP lenses offer excellent oxygen permeability and crisp optical clarity, particularly for patients with irregular astigmatism or high refractive errors where soft lenses underperform.