CPOA Contact Lens Basics 3 — Questions and Answers
Question 1: Which complication is characterized by blood vessels growing into the normally avascular cornea due to contact lens hypoxia?
- Giant papillary conjunctivitis
- Corneal neovascularization (Correct answer)
- Superior limbic keratoconjunctivitis
- Microbial keratitis
Correct answer: Corneal neovascularization
Corneal neovascularization (pannus) occurs when the cornea is oxygen-deprived, stimulating blood vessel ingrowth from the limbus.
Question 2: A rigid gas-permeable (RGP) lens that is too flat will typically:
- Decentrate inferiorly and show excessive movement (Correct answer)
- Adhere tightly to the cornea with minimal movement
- Cause central pooling on fluorescein assessment
- Show apical clearance with no bearing
Correct answer: Decentrate inferiorly and show excessive movement
A flat-fitting RGP lens rides on the apex of the cornea and moves excessively, often decentering inferiorly.
Question 3: What does the term 'orthokeratology' refer to in contact lens practice?
- Fitting lenses post-refractive surgery
- Using rigid lenses overnight to temporarily reshape the cornea (Correct answer)
- Prescribing lenses for keratoconus
- Fitting bifocal contact lenses
Correct answer: Using rigid lenses overnight to temporarily reshape the cornea
Orthokeratology (ortho-k) uses specially designed rigid lenses worn overnight to temporarily flatten the cornea and reduce myopia.
Question 4: Which contact lens design is most appropriate for a patient with irregular corneal astigmatism due to keratoconus?
- Soft spherical lens
- Soft toric lens
- Rigid gas-permeable lens (Correct answer)
- Daily disposable lens
Correct answer: Rigid gas-permeable lens
RGP lenses vault over the irregular corneal surface and provide a smooth optical surface via the tear lens, making them the preferred option for keratoconus.
Question 5: Giant papillary conjunctivitis (GPC) associated with contact lens wear most commonly affects which ocular surface?
- Bulbar conjunctiva
- Upper tarsal conjunctiva (Correct answer)
- Lower tarsal conjunctiva
- Corneal epithelium
Correct answer: Upper tarsal conjunctiva
GPC is characterized by large papillae on the upper tarsal (palpebral) conjunctiva, often caused by lens deposits or mechanical irritation.
Question 6: What is the recommended minimum waiting period after removing soft contact lenses before performing corneal topography for a new fit?
- 30 minutes
- 2 hours
- At least 2 weeks (Correct answer)
- No waiting period required
Correct answer: At least 2 weeks
Soft lenses can temporarily alter corneal shape; waiting at least 2 weeks ensures the cornea returns to its natural contour before topography.
Question 7: A patient using hydrogen peroxide lens care systems must neutralize the solution before inserting lenses to avoid:
- Lens discoloration
- Severe ocular burning and pain (Correct answer)
- Reduced disinfection efficacy
- Protein deposition on lenses
Correct answer: Severe ocular burning and pain
Inserting lenses still containing active hydrogen peroxide causes severe burning, stinging, and potential corneal damage.
CPOA Contact Lens Basics 3
Which complication is characterized by blood vessels growing into the normally avascular cornea due to contact lens hypoxia?