Contact Lens Basics Flashcards
7 cards from real CPOA 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 Basics flashcards as text
Which type of contact lens is specifically designed to vault over the entire cornea and rest on the sclera?
Answer: Scleral lens
Scleral lenses have large diameters (16–24 mm) that vault completely over the cornea and land on the scleral tissue, making them ideal for irregular corneas.
Contact lens-induced acute red eye (CLARE) is most often associated with which lens wear pattern?
Answer: Overnight or extended wear of contact lenses
CLARE typically occurs upon waking after sleeping in contact lenses due to hypoxia and bacterial toxin accumulation under the lens.
What is the purpose of using fluorescein dye during an RGP contact lens fitting?
Answer: To assess the fitting relationship between the lens and cornea
Fluorescein pools in the tear layer under the RGP lens and glows under cobalt blue light, revealing the fit pattern (bearing, clearance, alignment).
Which statement is correct regarding silicone hydrogel contact lens materials compared to conventional hydrogel materials?
Answer: They have higher oxygen permeability
Silicone hydrogel materials transmit significantly more oxygen to the cornea than conventional hydrogel materials, reducing hypoxia-related complications.
A patient's contact lens prescription specifies 'BC 8.6 / D 14.2 / -3.00 SPH.' What does 'SPH' indicate?
Answer: The lens is a spherical design with no cylinder correction
SPH (sphere) indicates this is a spherical lens without astigmatism correction, meaning no cylinder or axis is present.
When educating a patient about the risks of sleeping in contact lenses, which complication should be emphasized as the most serious?
Answer: Increased risk of microbial keratitis and corneal ulcers
Sleeping in contact lenses dramatically increases the risk of microbial keratitis, a serious infection that can lead to permanent vision loss.
Which solution is safe to use for topping off a contact lens case that still has old solution remaining in it?
Answer: The case should be emptied, rinsed with fresh solution, and refilled
Topping off old solution dilutes its disinfecting efficacy; the case must be emptied, rinsed with fresh solution, and completely refilled.