CPOA Contact Lens Basics 4 — Questions and Answers
Question 1: When instructing a new contact lens patient on proper hand hygiene, which type of soap should be recommended?
- Antibacterial soap with moisturizers
- Fragrance-free, lotion-free soap (Correct answer)
- Any liquid hand soap
- Hand sanitizer gel
Correct answer: Fragrance-free, lotion-free soap
Fragrance-free, lotion-free soaps are recommended because additives like lotions or fragrances can contaminate lenses and irritate eyes.
Question 2: Which parameter uniquely identifies a toric soft contact lens prescription compared to a spherical prescription?
- Sphere power and base curve
- Cylinder power and axis (Correct answer)
- Diameter and water content
- Replacement schedule and brand
Correct answer: Cylinder power and axis
Toric lenses are defined by their sphere power plus the cylinder power and axis needed to correct astigmatism.
Question 3: The 'add' power in a multifocal contact lens prescription is used to correct which vision condition?
- Myopia
- Hyperopia
- Astigmatism
- Presbyopia (Correct answer)
Correct answer: Presbyopia
Add power compensates for the loss of accommodative ability in presbyopic patients, allowing clear near vision.
Question 4: What is the most common organism responsible for Acanthamoeba keratitis in contact lens wearers?
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Acanthamoeba castellanii (Correct answer)
- Fusarium solani
Correct answer: Acanthamoeba castellanii
Acanthamoeba castellanii is the most common species causing this rare but severe corneal infection, often linked to rinsing lenses with tap water.
Question 5: A contact lens patient asks about 'monovision.' Which description is most accurate?
- Both eyes corrected for distance with one eye covered
- One eye corrected for distance and the other for near (Correct answer)
- Using a single contact lens in one eye only
- A lens design that corrects astigmatism in one meridian
Correct answer: One eye corrected for distance and the other for near
Monovision fits one eye (usually dominant) for distance and the other for near to address presbyopia without multifocal lenses.
Question 6: Which instruction is most important to convey to a patient regarding contact lens case hygiene?
- Rinse the case with tap water daily
- Replace the case every 1-3 months (Correct answer)
- Wipe the case dry with a cloth after each use
- Store the case in a cool, dark place filled with solution
Correct answer: Replace the case every 1-3 months
Contact lens cases are a major source of microbial contamination and should be replaced every 1–3 months to reduce infection risk.
Question 7: A soft contact lens with a diameter of 14.2 mm is considered:
- Small diameter
- Standard soft lens diameter (Correct answer)
- Large diameter scleral
- Mini-scleral
Correct answer: Standard soft lens diameter
Most soft contact lenses range from about 13.8 to 14.5 mm in diameter, with 14.2 mm falling within the standard range.
CPOA Contact Lens Basics 4
When instructing a new contact lens patient on proper hand hygiene, which type of soap should be recommended?